Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

424 files changed, 19769 insertions, 0 deletions

diff --git a/js/src/tests/test262/built-ins/Atomics/Symbol.toStringTag.js b/js/src/tests/test262/built-ins/Atomics/Symbol.toStringTag.js
new file mode 100644
index 0000000000..0e0721c000
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/Symbol.toStringTag.js
@@ -0,0 +1,28 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics-@@tostringtag
+description: >
+    `Symbol.toStringTag` property descriptor on Atomics
+info: |
+    The initial value of the @@toStringTag property is the String value
+    "Atomics".
+
+    This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+    false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics, Symbol, Symbol.toStringTag]
+---*/
+
+assert.sameValue(
+  Atomics[Symbol.toStringTag],
+  'Atomics',
+  'The value of Atomics[Symbol.toStringTag] is "Atomics"'
+);
+
+verifyNotEnumerable(Atomics, Symbol.toStringTag);
+verifyNotWritable(Atomics, Symbol.toStringTag);
+verifyConfigurable(Atomics, Symbol.toStringTag);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bad-range.js b/js/src/tests/test262/built-ins/Atomics/add/bad-range.js
new file mode 100644
index 0000000000..2654eb2364
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Test range checking of Atomics.add on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.add(view, IdxGen(view), 10);
+    }, '`Atomics.add(view, IdxGen(view), 10)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/add/bigint/bad-range.js
new file mode 100644
index 0000000000..86f2456e24
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.add
+description: >
+  Test range checking of Atomics.add on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+var buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.add(view, IdxGen(view), 10n);
+    }, '`Atomics.add(view, IdxGen(view), 10n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/add/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/add/bigint/good-views.js
new file mode 100644
index 0000000000..a042777b77
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bigint/good-views.js
@@ -0,0 +1,56 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.add
+description: Test Atomics.add on arrays that allow atomic operations.
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0n;
+  assert.sameValue(Atomics.add(view, 8, 10n), 0n, 'Atomics.add(view, 8, 10n) returns 0');
+  assert.sameValue(view[8], 10n, 'The value of view[8] is 10n');
+  assert.sameValue(Atomics.add(view, 8, -5n), 10n, 'Atomics.add(view, 8, -5n) returns 10n');
+  assert.sameValue(view[8], 5n, 'The value of view[8] is 5n');
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.add(view, 3, 0n),
+    control[0],
+    'Atomics.add(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.add(view, 3, 0n),
+    control[0],
+    'Atomics.add(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.add(view, 3, 0n),
+    control[0],
+    'Atomics.add(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.add(view, Idx, 0n), 37n, 'Atomics.add(view, Idx, 0) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/add/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..92387eec28
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.add(view, 0, 1n), 0n, 'Atomics.add(view, 0, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/add/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/add/browser.js b/js/src/tests/test262/built-ins/Atomics/add/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/add/descriptor.js b/js/src/tests/test262/built-ins/Atomics/add/descriptor.js
new file mode 100644
index 0000000000..9eda979c91
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: Testing descriptor property of Atomics.add
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'add', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/add/expected-return-value.js
new file mode 100644
index 0000000000..3498caa9a7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/expected-return-value.js
@@ -0,0 +1,39 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.add( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, add).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const newValue = 0b00000001000000001000000010000001;
+
+assert.sameValue(Atomics.add(i32a, 0, newValue), 0, 'Atomics.add(i32a, 0, newValue) returns 0');
+assert.sameValue(i32a[0], newValue, 'The value of i32a[0] equals the value of `newValue` (0b00000001000000001000000010000001)');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/good-views.js b/js/src/tests/test262/built-ins/Atomics/add/good-views.js
new file mode 100644
index 0000000000..fdb204d040
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/good-views.js
@@ -0,0 +1,57 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: Test Atomics.add on arrays that allow atomic operations.
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  // Add positive number
+  view[8] = 0;
+  assert.sameValue(Atomics.add(view, 8, 10), 0, 'Atomics.add(view, 8, 10) returns 0');
+  assert.sameValue(view[8], 10, 'The value of view[8] is 10');
+
+  // Add negative number
+  assert.sameValue(Atomics.add(view, 8, -5), 10, 'Atomics.add(view, 8, -5) returns 10');
+  assert.sameValue(view[8], 5, 'The value of view[8] is 5');
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.add(view, 3, 0), control[0],
+    'Atomics.add(view, 3, 0) returns the value of `control[0]` (-5)');
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.add(view, 3, 0), control[0],
+    'Atomics.add(view, 3, 0) returns the value of `control[0]` (12345)');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.add(view, 3, 0), control[0],
+    'Atomics.add(view, 3, 0) returns the value of `control[0]` (123456789)');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.add(view, Idx, 0), 37, 'Atomics.add(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/length.js b/js/src/tests/test262/built-ins/Atomics/add/length.js
new file mode 100644
index 0000000000..dbeba75cbf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add.length is 3.
+info: |
+  Atomics.add ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.add, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/name.js b/js/src/tests/test262/built-ins/Atomics/add/name.js
new file mode 100644
index 0000000000..4896e062f3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add.name is "add".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.add, 'name', {
+  value: 'add',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/add/non-shared-bufferdata.js
new file mode 100644
index 0000000000..2ca4c447f8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.add(view, 0, 1), 0, 'Atomics.add(view, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 1, 'Atomics.load(view, 0) returns 1');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/add/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..6c7c88cec1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.add(view, 0, 1);
+  }, `Atomics.add(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/non-views.js b/js/src/tests/test262/built-ins/Atomics/add/non-views.js
new file mode 100644
index 0000000000..c10fa26753
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Test Atomics.add on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.add(view, 0, 0);
+  }, '`Atomics.add(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/add/not-a-constructor.js
new file mode 100644
index 0000000000..723164589f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.add does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.add), false, 'isConstructor(Atomics.add) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.add(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.add(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/shell.js b/js/src/tests/test262/built-ins/Atomics/add/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..10ada1eceb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.2 Atomics.add ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, add).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.add(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..f52d769b76
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/add/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.2 Atomics.add ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, add).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.add(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bad-range.js b/js/src/tests/test262/built-ins/Atomics/and/bad-range.js
new file mode 100644
index 0000000000..8548ab5dc3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Test range checking of Atomics.and on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.and(view, IdxGen(view), 10);
+    }, '`Atomics.and(view, IdxGen(view), 10)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/and/bigint/bad-range.js
new file mode 100644
index 0000000000..a64ae66282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.and
+description: >
+  Test range checking of Atomics.and on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.and(view, IdxGen(view), 10n);
+    }, '`Atomics.and(view, IdxGen(view), 10n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/and/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/and/bigint/good-views.js
new file mode 100644
index 0000000000..ba66767532
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bigint/good-views.js
@@ -0,0 +1,86 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.and
+description: Test Atomics.and on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0x33333333n;
+  control[0] = 0x33333333n;
+
+  assert.sameValue(
+    Atomics.and(view, 8, 0x55555555n),
+    control[0],
+    'Atomics.and(view, 8, 0x55555555n) returns the value of `control[0]` (0x33333333n)'
+  );
+
+  control[0] = 0x11111111n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x11111111n)'
+  );
+
+  assert.sameValue(
+    Atomics.and(view, 8, 0xF0F0F0F0n),
+    control[0],
+    'Atomics.and(view, 8, 0xF0F0F0F0n) returns the value of `control[0]` (0x11111111n)'
+  );
+
+  control[0] = 0x10101010n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x10101010n)'
+  );
+
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.and(view, 3, 0n),
+    control[0],
+    'Atomics.and(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.and(view, 3, 0n),
+    control[0],
+    'Atomics.and(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.and(view, 3, 0n),
+    control[0],
+    'Atomics.and(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.and(view, Idx, 0n), 37n, 'Atomics.and(view, Idx, 0n) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/and/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..92f02253d2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.and(view, 0, 1n), 0n, 'Atomics.and(view, 0, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 0n, 'Atomics.load(view, 0) returns 0n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/and/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/and/browser.js b/js/src/tests/test262/built-ins/Atomics/and/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/and/descriptor.js b/js/src/tests/test262/built-ins/Atomics/and/descriptor.js
new file mode 100644
index 0000000000..14a0240a83
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: Testing descriptor property of Atomics.and
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'and', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/and/expected-return-value.js
new file mode 100644
index 0000000000..29605ae3f2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/expected-return-value.js
@@ -0,0 +1,48 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.and( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, and).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const a = 0b00000001000000001000000010000001;
+const b = 0b00000001111111111000000011111111;
+const c = 0b00000001000000001000000010000001;
+
+i32a[0] = a;
+
+assert.sameValue(
+  Atomics.and(i32a, 0, b),
+  a,
+  'Atomics.and(i32a, 0, b) returns the value of `a` (0b00000001000000001000000010000001)'
+);
+
+assert.sameValue(i32a[0], c, 'The value of i32a[0] equals the value of `c` (0b00000001000000001000000010000001)');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/good-views.js b/js/src/tests/test262/built-ins/Atomics/and/good-views.js
new file mode 100644
index 0000000000..532b75674d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/good-views.js
@@ -0,0 +1,72 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: Test Atomics.and on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  view[8] = 0x33333333;
+  control[0] = 0x33333333;
+  assert.sameValue(Atomics.and(view, 8, 0x55555555), control[0],
+    'Atomics.and(view, 8, 0x55555555) returns the value of `control[0]` (0x33333333)');
+
+  control[0] = 0x11111111;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x11111111)'
+  );
+  assert.sameValue(Atomics.and(view, 8, 0xF0F0F0F0), control[0],
+    'Atomics.and(view, 8, 0xF0F0F0F0) returns the value of `control[0]` (0x11111111)');
+
+  control[0] = 0x10101010;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x10101010)'
+  );
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.and(view, 3, 0), control[0],
+    'Atomics.and(view, 3, 0) returns the value of `control[0]` (-5)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.and(view, 3, 0), control[0],
+    'Atomics.and(view, 3, 0) returns the value of `control[0]` (12345)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.and(view, 3, 0), control[0],
+    'Atomics.and(view, 3, 0) returns the value of `control[0]` (123456789)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.and(view, Idx, 0), 37, 'Atomics.and(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/length.js b/js/src/tests/test262/built-ins/Atomics/and/length.js
new file mode 100644
index 0000000000..ef93eed764
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and.length is 3.
+info: |
+  Atomics.and ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.and, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/name.js b/js/src/tests/test262/built-ins/Atomics/and/name.js
new file mode 100644
index 0000000000..db8dc05d8c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and.name is "and".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.and, 'name', {
+  value: 'and',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/and/non-shared-bufferdata.js
new file mode 100644
index 0000000000..be959d353d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.and(view, 0, 1), 0, 'Atomics.and(view, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 0, 'Atomics.load(view, 0) returns 0');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/and/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..90987ae1ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.and(view, 0, 1);
+  }, `Atomics.and(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/non-views.js b/js/src/tests/test262/built-ins/Atomics/and/non-views.js
new file mode 100644
index 0000000000..49732f95c9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Test Atomics.and on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.and(view, 0, 0);
+  }, '`Atomics.and(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/and/not-a-constructor.js
new file mode 100644
index 0000000000..9f6fb08569
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.and does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.and), false, 'isConstructor(Atomics.and) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.and(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.and(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/shell.js b/js/src/tests/test262/built-ins/Atomics/and/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..edfe4f88d0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.3 Atomics.and ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, and).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.and(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..30b017f6b4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/and/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.3 Atomics.and ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, and).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.and(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/browser.js b/js/src/tests/test262/built-ins/Atomics/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bad-range.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bad-range.js
new file mode 100644
index 0000000000..507b33750c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: >
+  Test range checking of Atomics.compareExchange on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.compareExchange(view, IdxGen(view), 10, 0);
+    }, '`Atomics.compareExchange(view, IdxGen(view), 10, 0)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/bad-range.js
new file mode 100644
index 0000000000..1799f1cefc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.compareexchange
+description: >
+  Test range checking of Atomics.compareExchange on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.compareExchange(view, IdxGen(view), 10, 0n);
+    }, '`Atomics.compareExchange(view, IdxGen(view), 10, 0n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/good-views.js
new file mode 100644
index 0000000000..331aa9cf6b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/good-views.js
@@ -0,0 +1,94 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.compareexchange
+description: Test Atomics.compareExchange on arrays that allow atomic operations.
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 8, 0n, 10n),
+    0n,
+    'Atomics.compareExchange(view, 8, 0n, 10n) returns 0n'
+  );
+
+  assert.sameValue(view[8], 10n, 'The value of view[8] is 10n');
+  view[8] = 0n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 8, 1n, 10n),
+    0n,
+    'Atomics.compareExchange(view, 8, 1n, 10n) returns 0n'
+  );
+
+  assert.sameValue(view[8], 0n, 'The value of view[8] is 0n');
+  view[8] = 0n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 8, 0n, -5n),
+    0n,
+    'Atomics.compareExchange(view, 8, 0n, -5n) returns 0n'
+  );
+
+  control[0] = -5n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (-5n)'
+  );
+
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 3, -5n, 0n),
+    control[0],
+    'Atomics.compareExchange(view, 3, -5n, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 3, 12345n, 0n),
+    control[0],
+    'Atomics.compareExchange(view, 3, 12345n, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.compareExchange(view, 3, 123456789n, 0n),
+    control[0],
+    'Atomics.compareExchange(view, 3, 123456789n, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  assert.sameValue(view[3], 0n, 'The value of view[3] is 0n');
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+
+    assert.sameValue(
+      Atomics.compareExchange(view, Idx, 37n, 0n),
+      37n,
+      'Atomics.compareExchange(view, Idx, 37n, 0n) returns 37n'
+    );
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..1952abaff5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  Atomics.compareExchange will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.compareExchange(view, 0, 0n, 1n), 0n, 'Atomics.compareExchange(view, 0, 0n, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/browser.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/descriptor.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/descriptor.js
new file mode 100644
index 0000000000..cd273df6c4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: Testing descriptor property of Atomics.compareExchange
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'compareExchange', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/expected-return-value.js
new file mode 100644
index 0000000000..dc2a778df2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/expected-return-value.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  Atomics.compareExchange returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.compareExchange( typedArray, index, expectedValue, replacementValue )
+
+  ...
+  12. Let compareExchange denote a semantic function of two List of
+      byte values arguments that returns the second argument if the
+      first argument is element-wise equal to expectedBytes.
+  13. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+      elementType, replacement, compareExchange).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4);
+const i32a = new Int32Array(buffer);
+const update = 0b00000001000000001000000010000001;
+
+i32a[0] = update;
+
+assert.sameValue(
+  Atomics.compareExchange(i32a, 0, update, 0),
+  update,
+  'Atomics.compareExchange(i32a, 0, update, 0) returns the value of `update` (0b00000001000000001000000010000001)'
+);
+assert.sameValue(i32a[0], 0, 'The value of i32a[0] is 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/good-views.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/good-views.js
new file mode 100644
index 0000000000..3f1e5fd82c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/good-views.js
@@ -0,0 +1,77 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: Test Atomics.compareExchange on arrays that allow atomic operations.
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  // Performs the exchange
+  view[8] = 0;
+  assert.sameValue(
+    Atomics.compareExchange(view, 8, 0, 10),
+    0,
+    'Atomics.compareExchange(view, 8, 0, 10) returns 0'
+  );
+  assert.sameValue(view[8], 10, 'The value of view[8] is 10');
+
+  view[8] = 0;
+  assert.sameValue(Atomics.compareExchange(view, 8, 1, 10), 0,
+    'Atomics.compareExchange(view, 8, 1, 10) returns 0');
+  assert.sameValue(view[8], 0, 'The value of view[8] is 0');
+
+  view[8] = 0;
+  assert.sameValue(Atomics.compareExchange(view, 8, 0, -5), 0,
+    'Atomics.compareExchange(view, 8, 0, -5) returns 0');
+  control[0] = -5;
+  assert.sameValue(view[8], control[0], 'The value of view[8] equals the value of `control[0]` (-5)');
+
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.compareExchange(view, 3, -5, 0), control[0],
+    'Atomics.compareExchange(view, 3, -5, 0) returns the value of `control[0]` (-5)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.compareExchange(view, 3, 12345, 0), control[0],
+    'Atomics.compareExchange(view, 3, 12345, 0) returns the value of `control[0]` (12345)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.compareExchange(view, 3, 123456789, 0), control[0],
+    'Atomics.compareExchange(view, 3, 123456789, 0) returns the value of `control[0]` (123456789)');
+  assert.sameValue(view[3], 0, 'The value of view[3] is 0');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(
+      Atomics.compareExchange(view, Idx, 37, 0),
+      37,
+      'Atomics.compareExchange(view, Idx, 37, 0) returns 37'
+    );
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/length.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/length.js
new file mode 100644
index 0000000000..f850703350
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: >
+  Atomics.compareExchange.length is 4.
+info: |
+  Atomics.compareExchange ( ia, index, expect, replace )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.compareExchange, 'length', {
+  value: 4,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/name.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/name.js
new file mode 100644
index 0000000000..df2e3f0643
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: >
+  Atomics.compareExchange.name is "compareExchange".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.compareExchange, 'name', {
+  value: 'compareExchange',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-bufferdata.js
new file mode 100644
index 0000000000..a5d3058801
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  Atomics.compareExchange will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.compareExchange(view, 0, 0, 1), 0, 'Atomics.compareExchange(view, 0, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 1, 'Atomics.load(view, 0) returns 1');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..45df6f8cb5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  Atomics.compareExchange throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.compareExchange(view, 0, 0, 0);
+  }, `Atomics.compareExchange(new ${TA.name}(buffer), 0, 0, 0) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/non-views.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-views.js
new file mode 100644
index 0000000000..f3be53cbe7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareexchange
+description: >
+  Test Atomics.compareExchange on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.compareExchange(view, 0, 0, 0);
+  }, '`Atomics.compareExchange(view, 0, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/not-a-constructor.js
new file mode 100644
index 0000000000..c42a00268b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/not-a-constructor.js
@@ -0,0 +1,36 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.compareExchange does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(
+  isConstructor(Atomics.compareExchange),
+  false,
+  'isConstructor(Atomics.compareExchange) must return false'
+);
+
+assert.throws(TypeError, () => {
+  new Atomics.compareExchange(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.compareExchange(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/shell.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-expectedValue-coercion.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-expectedValue-coercion.js
new file mode 100644
index 0000000000..7392e72344
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-expectedValue-coercion.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  TypedArray type is validated before `expectedValue` argument is coerced.
+info: |
+  24.4.4 Atomics.compareExchange ( typedArray, index, expectedValue, replacementValue )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var expectedValue = {
+  valueOf() {
+    throw new Test262Error("expectedValue coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.compareExchange(typedArray, 0, expectedValue, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..5ddd207d24
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.4 Atomics.compareExchange ( typedArray, index, expectedValue, replacementValue )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.compareExchange(typedArray, index, 0, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-replacementValue-coercion.js b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-replacementValue-coercion.js
new file mode 100644
index 0000000000..065a032809
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/compareExchange/validate-arraytype-before-replacementValue-coercion.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.compareExchange
+description: >
+  TypedArray type is validated before `replacementValue` argument is coerced.
+info: |
+  24.4.4 Atomics.compareExchange ( typedArray, index, expectedValue, replacementValue )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var replacementValue = {
+  valueOf() {
+    throw new Test262Error("replacementValue coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.compareExchange(typedArray, 0, 0, replacementValue);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bad-range.js b/js/src/tests/test262/built-ins/Atomics/exchange/bad-range.js
new file mode 100644
index 0000000000..23cda3ced4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Test range checking of Atomics.exchange on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.exchange(view, IdxGen(view), 10, 0);
+    }, '`Atomics.exchange(view, IdxGen(view), 10, 0)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/bad-range.js
new file mode 100644
index 0000000000..205ecdcd59
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.exchange
+description: >
+  Test range checking of Atomics.exchange on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+var buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.exchange(view, IdxGen(view), 10n, 0n);
+    }, '`Atomics.exchange(view, IdxGen(view), 10n, 0n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/good-views.js
new file mode 100644
index 0000000000..af301eeb5a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/good-views.js
@@ -0,0 +1,74 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.exchange
+description: Test Atomics.exchange on arrays that allow atomic operations.
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0n;
+  assert.sameValue(Atomics.exchange(view, 8, 10n), 0n, 'Atomics.exchange(view, 8, 10n) returns 0n');
+  assert.sameValue(view[8], 10n, 'The value of view[8] is 10n');
+
+  assert.sameValue(
+    Atomics.exchange(view, 8, -5n),
+    10n,
+    'Atomics.exchange(view, 8, -5n) returns 10n'
+  );
+
+  control[0] = -5n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (-5n)'
+  );
+
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.exchange(view, 3, 0n),
+    control[0],
+    'Atomics.exchange(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.exchange(view, 3, 0n),
+    control[0],
+    'Atomics.exchange(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.exchange(view, 3, 0n),
+    control[0],
+    'Atomics.exchange(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+
+    assert.sameValue(
+      Atomics.exchange(view, Idx, 0n),
+      37n,
+      'Atomics.exchange(view, Idx, 0n) returns 37n'
+    );
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..8bf7f7a22c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.exchange will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.exchange(view, 0, 1n), 0n, 'Atomics.exchange(view, 0, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/browser.js b/js/src/tests/test262/built-ins/Atomics/exchange/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/descriptor.js b/js/src/tests/test262/built-ins/Atomics/exchange/descriptor.js
new file mode 100644
index 0000000000..dbe420715d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: Testing descriptor property of Atomics.exchange
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'exchange', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/exchange/expected-return-value.js
new file mode 100644
index 0000000000..eaf176fc03
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/expected-return-value.js
@@ -0,0 +1,47 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.and returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.exchange( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, second).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const update = 0b00000001000000001000000010000001;
+
+assert.sameValue(
+  Atomics.exchange(i32a, 0, update),
+  0,
+  'Atomics.exchange(i32a, 0, update) returns 0'
+);
+assert.sameValue(
+  i32a[0],
+  update,
+  'The value of i32a[0] equals the value of `update` (0b00000001000000001000000010000001)'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/good-views.js b/js/src/tests/test262/built-ins/Atomics/exchange/good-views.js
new file mode 100644
index 0000000000..80eab9dfa6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/good-views.js
@@ -0,0 +1,58 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: Test Atomics.exchange on arrays that allow atomic operations.
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  view[8] = 0;
+  assert.sameValue(Atomics.exchange(view, 8, 10), 0,
+    'Atomics.exchange(view, 8, 10) returns 0');
+  assert.sameValue(view[8], 10, 'The value of view[8] is 10');
+
+  assert.sameValue(Atomics.exchange(view, 8, -5), 10,
+    'Atomics.exchange(view, 8, -5) returns 10');
+  control[0] = -5;
+  assert.sameValue(view[8], control[0], 'The value of view[8] equals the value of `control[0]` (-5)');
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.exchange(view, 3, 0), control[0],
+    'Atomics.exchange(view, 3, 0) returns the value of `control[0]` (-5)');
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.exchange(view, 3, 0), control[0],
+    'Atomics.exchange(view, 3, 0) returns the value of `control[0]` (12345)');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.exchange(view, 3, 0), control[0],
+    'Atomics.exchange(view, 3, 0) returns the value of `control[0]` (123456789)');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.exchange(view, Idx, 0), 37, 'Atomics.exchange(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/length.js b/js/src/tests/test262/built-ins/Atomics/exchange/length.js
new file mode 100644
index 0000000000..4a7bb32ed5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.exchange.length is 3.
+info: |
+  Atomics.exchange ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.exchange, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/name.js b/js/src/tests/test262/built-ins/Atomics/exchange/name.js
new file mode 100644
index 0000000000..127840b85f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.exchange.name is "exchange".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.exchange, 'name', {
+  value: 'exchange',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-bufferdata.js
new file mode 100644
index 0000000000..463ae4ebb6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.exchange will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.exchange(view, 0, 1), 0, 'Atomics.exchange(view, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 1, 'Atomics.load(view, 0) returns 1');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..e3b53900aa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/non-shared-int-views-throws.js
@@ -0,0 +1,20 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.add
+description: >
+  Atomics.add throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.throws(TypeError, function() {
+    Atomics.add(view, 0, 1);
+  }, `Atomics.add(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/non-views.js b/js/src/tests/test262/built-ins/Atomics/exchange/non-views.js
new file mode 100644
index 0000000000..8cc0d76b0a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Test Atomics.exchange on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.exchange(view, 0, 0);
+  }, '`Atomics.exchange(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/nonshared-int-views.js b/js/src/tests/test262/built-ins/Atomics/exchange/nonshared-int-views.js
new file mode 100644
index 0000000000..5a45151e87
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/nonshared-int-views.js
@@ -0,0 +1,22 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  Atomics.exchange throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.exchange(view, 0, 0);
+  }, `Atomics.exchange(new ${TA.name}(buffer), 0, 0) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/exchange/not-a-constructor.js
new file mode 100644
index 0000000000..2115000021
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.exchange does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.exchange), false, 'isConstructor(Atomics.exchange) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.exchange(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.exchange(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/shell.js b/js/src/tests/test262/built-ins/Atomics/exchange/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..5e8b5c17e3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.5 Atomics.exchange ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, second).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.exchange(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..eb5589c6ea
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/exchange/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.exchange
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.5 Atomics.exchange ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, second).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.exchange(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/expected-return-value.js
new file mode 100644
index 0000000000..3eceb1de2d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/expected-return-value.js
@@ -0,0 +1,38 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.isLockFree
+description: >
+  Atomics.isLockFree returns a boolean that indicates whether
+  operations on datum of size will be performed without the agent
+  acquiring a lock outside of size bytes.
+info: |
+  Atomics.isLockFree( size )
+
+  1. Let n be ? ToInteger(size).
+  2. Let AR be the Agent Record of the surrounding agent.
+  3. If n equals 1, return AR.[[IsLockFree1]].
+  4. If n equals 2, return AR.[[IsLockFree2]].
+  5. If n equals 4, return true.
+  6. If n equals 8, return AR.[[IsLockFree8]].
+  7. Return false.
+
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+includes: [testBigIntTypedArray.js]
+---*/
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  var observed = Atomics.isLockFree(TA.BYTES_PER_ELEMENT);
+
+  assert.sameValue(
+    Atomics.isLockFree(TA.BYTES_PER_ELEMENT),
+    observed,
+    'Atomics.isLockFree(TA.BYTES_PER_ELEMENT) returns the value of `observed` (Atomics.isLockFree(TA.BYTES_PER_ELEMENT))'
+  );
+});
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/browser.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/corner-cases.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/corner-cases.js
new file mode 100644
index 0000000000..f398e06100
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/corner-cases.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.islockfree
+description: >
+  Test isLockFree on various non-intuitive arguments
+features: [Atomics]
+---*/
+
+assert.sameValue(
+  Atomics.isLockFree(hide(3, Number.NaN)),
+  false,
+  'Atomics.isLockFree(hide(3, Number.NaN)) returns false'
+);
+assert.sameValue(
+  Atomics.isLockFree(hide(3, -1)),
+  false,
+  'Atomics.isLockFree(hide(3, -1)) returns false'
+);
+assert.sameValue(
+  Atomics.isLockFree(hide(3, 3.14)),
+  false,
+  'Atomics.isLockFree(hide(3, 3.14)) returns false'
+);
+assert.sameValue(
+  Atomics.isLockFree(hide(3, 0)),
+  false,
+  'Atomics.isLockFree(hide(3, 0)) returns false'
+);
+
+assert.sameValue(
+  Atomics.isLockFree('1'),
+  Atomics.isLockFree(1),
+  'Atomics.isLockFree(\'1\') returns Atomics.isLockFree(1)'
+);
+assert.sameValue(
+  Atomics.isLockFree('3'),
+  Atomics.isLockFree(3),
+  'Atomics.isLockFree(\'3\') returns Atomics.isLockFree(3)'
+);
+
+assert.sameValue(
+  Atomics.isLockFree(true),
+  Atomics.isLockFree(1),
+  'Atomics.isLockFree(true) returns Atomics.isLockFree(1)'
+);
+
+assert.sameValue(
+  Atomics.isLockFree(1),
+  Atomics.isLockFree({valueOf: () => 1}),
+  'Atomics.isLockFree(1) returns Atomics.isLockFree({valueOf: () => 1})'
+);
+assert.sameValue(
+  Atomics.isLockFree(3),
+  Atomics.isLockFree({valueOf: () => 3}),
+  'Atomics.isLockFree(3) returns Atomics.isLockFree({valueOf: () => 3})'
+);
+assert.sameValue(
+  Atomics.isLockFree(1),
+  Atomics.isLockFree({toString: () => '1'}),
+  'Atomics.isLockFree(1) returns Atomics.isLockFree({toString: () => \'1\'})'
+);
+assert.sameValue(
+  Atomics.isLockFree(3),
+  Atomics.isLockFree({toString: () => '3'}),
+  'Atomics.isLockFree(3) returns Atomics.isLockFree({toString: () => \'3\'})'
+);
+
+function hide(k, x) {
+  if (k) {
+    return hide(k - 3, x) + x;
+  }
+  return 0;
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/descriptor.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/descriptor.js
new file mode 100644
index 0000000000..898aa096a2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.islockfree
+description: Testing descriptor property of Atomics.isLockFree
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'isLockFree', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/expected-return-value.js
new file mode 100644
index 0000000000..b7cdc26857
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/expected-return-value.js
@@ -0,0 +1,114 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.islockfree
+description: >
+  Atomics.isLockFree( size )
+    Let n be ? ToInteger(size).
+    Let AR be the Agent Record of the surrounding agent.
+    If n equals 1, return AR.[[IsLockFree1]].
+    If n equals 2, return AR.[[IsLockFree2]].
+    If n equals 4, return true.
+    If n equals 8, return AR.[[IsLockFree8]].
+    Return false.
+features: [Atomics, Array.prototype.includes]
+---*/
+
+// These are the only counts that we care about tracking.
+var isLockFree1;
+var isLockFree2;
+var isLockFree8;
+
+{
+  isLockFree1 = Atomics.isLockFree(1);
+  //
+  // If n equals 1, return AR.[[IsLockFree1]].
+  //
+  assert.sameValue(typeof isLockFree1, 'boolean', 'The value of `typeof isLockFree1` is "boolean"');
+  // Once the values of [[Signifier]], [[IsLockFree1]], [[IsLockFree2]],
+  // and [[IsLockFree8]] have been observed by any agent in the agent
+  // cluster they cannot change.
+  assert.sameValue(
+    Atomics.isLockFree(1),
+    isLockFree1,
+    'Atomics.isLockFree(1) returns the value of `isLockFree1` (Atomics.isLockFree(1))'
+  );
+};
+{
+  isLockFree2 = Atomics.isLockFree(2);
+  //
+  // If n equals 2, return AR.[[IsLockFree2]].
+  //
+  assert.sameValue(typeof isLockFree2, 'boolean', 'The value of `typeof isLockFree2` is "boolean"');
+  // Once the values of [[Signifier]], [[IsLockFree1]], [[IsLockFree2]],
+  // and [[IsLockFree8]] have been observed by any agent in the agent
+  // cluster they cannot change.
+  assert.sameValue(
+    Atomics.isLockFree(2),
+    isLockFree2,
+    'Atomics.isLockFree(2) returns the value of `isLockFree2` (Atomics.isLockFree(2))'
+  );
+};
+{
+  let isLockFree4 = Atomics.isLockFree(4);
+  //
+  // If n equals 4, return true.
+  //
+  assert.sameValue(typeof isLockFree4, 'boolean', 'The value of `typeof isLockFree4` is "boolean"');
+  assert.sameValue(isLockFree4, true, 'The value of `isLockFree4` is true');
+};
+
+{
+  isLockFree8 = Atomics.isLockFree(8);
+  //
+  // If n equals 8, return AR.[[IsLockFree8]].
+  //
+  assert.sameValue(typeof isLockFree8, 'boolean', 'The value of `typeof isLockFree8` is "boolean"');
+  // Once the values of [[Signifier]], [[IsLockFree1]], [[IsLockFree2]],
+  // and [[IsLockFree8]] have been observed by any agent in the agent
+  // cluster they cannot change.
+  assert.sameValue(
+    Atomics.isLockFree(8),
+    isLockFree8,
+    'Atomics.isLockFree(8) returns the value of `isLockFree8` (Atomics.isLockFree(8))'
+  );
+};
+
+{
+  for (let i = 0; i < 12; i++) {
+    if (![1, 2, 4, 8].includes(i)) {
+      assert.sameValue(Atomics.isLockFree(i), false, 'Atomics.isLockFree(i) returns false');
+    }
+  }
+};
+
+assert.sameValue(
+  Atomics.isLockFree(1),
+  isLockFree1,
+  'Atomics.isLockFree(1) returns the value of `isLockFree1` (Atomics.isLockFree(1))'
+);
+assert.sameValue(
+  Atomics.isLockFree(2),
+  isLockFree2,
+  'Atomics.isLockFree(2) returns the value of `isLockFree2` (Atomics.isLockFree(2))'
+);
+assert.sameValue(
+  Atomics.isLockFree(8),
+  isLockFree8,
+  'Atomics.isLockFree(8) returns the value of `isLockFree8` (Atomics.isLockFree(8))'
+);
+
+// Duplicates behavior created by loop from above
+assert.sameValue(Atomics.isLockFree(3), false, 'Atomics.isLockFree(3) returns false');
+assert.sameValue(Atomics.isLockFree(4), true, 'Atomics.isLockFree(4) returns true');
+assert.sameValue(Atomics.isLockFree(5), false, 'Atomics.isLockFree(5) returns false');
+assert.sameValue(Atomics.isLockFree(6), false, 'Atomics.isLockFree(6) returns false');
+assert.sameValue(Atomics.isLockFree(7), false, 'Atomics.isLockFree(7) returns false');
+assert.sameValue(Atomics.isLockFree(9), false, 'Atomics.isLockFree(9) returns false');
+assert.sameValue(Atomics.isLockFree(10), false, 'Atomics.isLockFree(10) returns false');
+assert.sameValue(Atomics.isLockFree(11), false, 'Atomics.isLockFree(11) returns false');
+assert.sameValue(Atomics.isLockFree(12), false, 'Atomics.isLockFree(12) returns false');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/length.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/length.js
new file mode 100644
index 0000000000..95f2343657
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.islockfree
+description: >
+  Atomics.isLockFree.length is 1.
+info: |
+  Atomics.isLockFree ( x )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.isLockFree, 'length', {
+  value: 1,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/name.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/name.js
new file mode 100644
index 0000000000..78022fe120
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.islockfree
+description: >
+  Atomics.isLockFree.name is "isLockFree".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.isLockFree, 'name', {
+  value: 'isLockFree',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/not-a-constructor.js
new file mode 100644
index 0000000000..03202213e7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.isLockFree does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.isLockFree), false, 'isConstructor(Atomics.isLockFree) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.isLockFree(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.isLockFree(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/isLockFree/shell.js b/js/src/tests/test262/built-ins/Atomics/isLockFree/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/isLockFree/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bad-range.js b/js/src/tests/test262/built-ins/Atomics/load/bad-range.js
new file mode 100644
index 0000000000..3dfe8ae858
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Test range checking of Atomics.load on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.load(view, IdxGen(view));
+    }, '`Atomics.load(view, IdxGen(view))` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/load/bigint/bad-range.js
new file mode 100644
index 0000000000..bdb8eed01e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bigint/bad-range.js
@@ -0,0 +1,24 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Test range checking of Atomics.load on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.load(view, IdxGen(view));
+    }, '`Atomics.load(view, IdxGen(view))` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/load/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/load/bigint/good-views.js
new file mode 100644
index 0000000000..995587f1eb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bigint/good-views.js
@@ -0,0 +1,51 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.load
+description: Test Atomics.load on arrays that allow atomic operations.
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.load(view, 3),
+    control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.load(view, 3),
+    control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.load(view, 3),
+    control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.load(view, Idx), 37n, 'Atomics.load(view, Idx) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/load/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..74d61a6988
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bigint/non-shared-bufferdata.js
@@ -0,0 +1,17 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.load(view, 0), 0n, 'Atomics.load(view, 0) returns 0n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/load/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/load/browser.js b/js/src/tests/test262/built-ins/Atomics/load/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/load/descriptor.js b/js/src/tests/test262/built-ins/Atomics/load/descriptor.js
new file mode 100644
index 0000000000..d3d6899b29
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: Testing descriptor property of Atomics.load
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'load', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/load/expected-return-value.js
new file mode 100644
index 0000000000..bcbeb5b99d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/expected-return-value.js
@@ -0,0 +1,48 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.load( typedArray, index, value )
+
+  1. Return ? AtomicLoad(typedArray, index).
+
+  AtomicLoad( typedArray, index )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+  3. Let arrayTypeName be typedArray.[[TypedArrayName]].
+  4. Let elementSize be the Number value of the Element Size value
+      specified in Table 56 for arrayTypeName.
+  5. Let elementType be the String value of the Element Type value
+      in Table 56 for arrayTypeName.
+  6. Let offset be typedArray.[[ByteOffset]].
+  7. Let indexedPosition be (i × elementSize) + offset.
+  8. Return GetValueFromBuffer(buffer, indexedPosition, elementType,
+      true, "SeqCst").
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const update = 0b00000001000000001000000010000001;
+
+assert.sameValue(Atomics.load(i32a, 0), 0, 'Atomics.load(i32a, 0) returns 0');
+
+i32a[0] = update;
+
+assert.sameValue(
+  Atomics.load(i32a, 0),
+  update,
+  'Atomics.load(i32a, 0) returns the value of `update` (0b00000001000000001000000010000001)'
+);
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/good-views.js b/js/src/tests/test262/built-ins/Atomics/load/good-views.js
new file mode 100644
index 0000000000..6f77377428
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/good-views.js
@@ -0,0 +1,49 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: Test Atomics.load on arrays that allow atomic operations.
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.load(view, 3), control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (-5)');
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.load(view, 3), control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (12345)');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.load(view, 3), control[0],
+    'Atomics.load(view, 3) returns the value of `control[0]` (123456789)');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.load(view, Idx), 37, 'Atomics.load(view, Idx) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/length.js b/js/src/tests/test262/built-ins/Atomics/load/length.js
new file mode 100644
index 0000000000..20ca0c90f6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load.length is 2.
+info: |
+  Atomics.load ( ia, index )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.load, 'length', {
+  value: 2,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/name.js b/js/src/tests/test262/built-ins/Atomics/load/name.js
new file mode 100644
index 0000000000..3b78cfe95b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load.name is "load".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.load, 'name', {
+  value: 'load',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/load/non-shared-bufferdata.js
new file mode 100644
index 0000000000..73ae85260c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/non-shared-bufferdata.js
@@ -0,0 +1,20 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.load(view, 0), 0, 'Atomics.load(view, 0) returns 0');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/load/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..a8bb46083c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/non-shared-int-views-throws.js
@@ -0,0 +1,20 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Atomics.load throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.throws(TypeError, function() {
+    Atomics.load(view, 0);
+  }, `Atomics.load(new ${TA.name}(buffer), 0) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/non-views.js b/js/src/tests/test262/built-ins/Atomics/load/non-views.js
new file mode 100644
index 0000000000..a88dc89ee8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.load
+description: >
+  Test Atomics.load on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.load(view, 0);
+  }, '`Atomics.load(view, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/load/not-a-constructor.js
new file mode 100644
index 0000000000..270660c5cf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.load does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.load), false, 'isConstructor(Atomics.load) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.load(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.load(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/load/shell.js b/js/src/tests/test262/built-ins/Atomics/load/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/load/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/load/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..70ef58f258
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/load/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.7 Atomics.load ( typedArray, index )
+    1. Return ? AtomicLoad(typedArray, index).
+
+  24.4.1.12 AtomicLoad ( typedArray, index )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.load(typedArray, index);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bad-range.js b/js/src/tests/test262/built-ins/Atomics/notify/bad-range.js
new file mode 100644
index 0000000000..78d1f0336a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bad-range.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test range checking of Atomics.notify on arrays that allow atomic operations
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ..
+
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.notify(i32a, IdxGen(i32a), 0);
+  }, '`Atomics.notify(i32a, IdxGen(i32a), 0)` throws RangeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/bad-range.js
new file mode 100644
index 0000000000..469d169ec9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/bad-range.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test range checking of Atomics.notify on arrays that allow atomic operations
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ..
+
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.notify(i64a, IdxGen(i64a), 0);
+  }, '`Atomics.notify(i64a, IdxGen(i64a), 0)` throws RangeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-bigint64-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-bigint64-typedarray-throws.js
new file mode 100644
index 0000000000..94fc29e40d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-bigint64-typedarray-throws.js
@@ -0,0 +1,37 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a TypeError if typedArray arg is not an BigInt64Array
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      5.If onlyInt32 is true, then
+        If typeName is not "BigInt64Array", throw a TypeError exception.
+features: [Atomics, BigInt, TypedArray]
+---*/
+
+const i64a = new BigUint64Array(
+  new SharedArrayBuffer(BigUint64Array.BYTES_PER_ELEMENT * 8)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, 0, 0);
+}, '`Atomics.wait(i64a, 0, 0)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, poisoned, poisoned);
+}, '`Atomics.wait(i64a, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-count-evaluation-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-count-evaluation-throws.js
new file mode 100644
index 0000000000..5c5781f429
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-count-evaluation-throws.js
@@ -0,0 +1,36 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Evaluates index before returning 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+    Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+  Else,
+    Let intCount be ? ToInteger(count).
+    Let c be max(intCount, 0).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i64a, poisoned, 0);
+}, '`Atomics.notify(i64a, poisoned, 0)` throws Test262Error');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-index-evaluation-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-index-evaluation-throws.js
new file mode 100644
index 0000000000..c345fa7265
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-index-evaluation-throws.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Evaluates index before returning 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  Let i be ? ValidateAtomicAccess(typedArray, index).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i64a, 0, poisoned);
+}, '`Atomics.notify(i64a, 0, poisoned)` throws Test262Error');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-non-shared-int-views-throws.js
new file mode 100644
index 0000000000..274bb87374
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-non-shared-int-views-throws.js
@@ -0,0 +1,24 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Atomics.notify throws on non-shared integer TypedArrays
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+
+const nonsab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new BigUint64Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new BigUint64Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-returns-0.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-returns-0.js
new file mode 100644
index 0000000000..2662027e8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/non-shared-bufferdata-returns-0.js
@@ -0,0 +1,24 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Returns 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+
+assert.sameValue(Atomics.notify(i64a, 0, 0), 0, 'Atomics.notify(i64a, 0, 0) returns 0');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/notify-all-on-loc.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/notify-all-on-loc.js
new file mode 100644
index 0000000000..322eb5376c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/notify-all-on-loc.js
@@ -0,0 +1,92 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies all waiters on a location, but does not
+  notify waiters on other locations.
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Waiters on this will be woken
+const WAIT_FAKE = 1;              // Waiters on this will not be woken
+const RUNNING = 2;                // Accounting of live agents
+const NOTIFY_INDEX = 3;             // Accounting for too early timeouts
+const NUMAGENT = 3;
+const TIMEOUT_AGENT_MESSAGES = 2; // Number of messages for the timeout agent
+const BUFFER_SIZE = 4;
+
+// Long timeout to ensure the agent doesn't timeout before the main agent calls
+// `Atomics.notify`.
+const TIMEOUT = $262.agent.timeouts.long;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i64a = new BigInt64Array(sab);
+      Atomics.add(i64a, ${RUNNING}, 1n);
+
+      $262.agent.report("A " + Atomics.wait(i64a, ${WAIT_INDEX}, 0n));
+      $262.agent.leaving();
+    });
+  `);
+}
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // This will always time out.
+    $262.agent.report("B " + Atomics.wait(i64a, ${WAIT_FAKE}, 0n, ${TIMEOUT}));
+
+    // If this value is not 1n, then the agent timeout before the main agent
+    // called Atomics.notify.
+    const result = Atomics.load(i64a, ${NOTIFY_INDEX}) === 1n
+                   ? "timeout after Atomics.notify"
+                   : "timeout before Atomics.notify";
+    $262.agent.report("W " + result);
+
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i64a, RUNNING, BigInt(NUMAGENT + 1));
+
+// Try to yield control to ensure the agent actually started to wait. If we
+// don't, we risk sending the notification before agents are sleeping, and we hang.
+$262.agent.tryYield();
+
+// Notify all waiting on WAIT_INDEX, should be 3 always, they won't time out.
+assert.sameValue(
+  Atomics.notify(i64a, WAIT_INDEX),
+  NUMAGENT,
+  'Atomics.notify(i64a, WAIT_INDEX) returns the value of `NUMAGENT`'
+);
+
+Atomics.store(i64a, NOTIFY_INDEX, 1n);
+
+const reports = [];
+for (var i = 0; i < NUMAGENT  + TIMEOUT_AGENT_MESSAGES; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(reports[i], 'A ok', 'The value of reports[i] is "A ok"');
+}
+assert.sameValue(reports[NUMAGENT], 'B timed-out', 'The value of reports[NUMAGENT] is "B timed-out"');
+assert.sameValue(reports[NUMAGENT + 1], "W timeout after Atomics.notify",
+                 'The value of reports[NUMAGENT + 1] is "W timeout after Atomics.notify"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/null-bufferdata-throws.js
new file mode 100644
index 0000000000..99bfc3cff9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/null-bufferdata-throws.js
@@ -0,0 +1,39 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  A null value for bufferData throws a TypeError
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is null, return false.
+includes: [detachArrayBuffer.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i64a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.notify(i64a, poisoned, poisoned);
+}, '`Atomics.notify(i64a, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/notify/bigint/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/bigint/shell.js
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/browser.js b/js/src/tests/test262/built-ins/Atomics/notify/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-boundary-cases.js b/js/src/tests/test262/built-ins/Atomics/notify/count-boundary-cases.js
new file mode 100644
index 0000000000..e343a57e58
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-boundary-cases.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Allowed boundary cases for 'count' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  ...
+  3. If count is undefined, let c be +∞.
+  4. Else,
+    a. Let intCount be ? ToInteger(count).
+  ...
+
+  ToInteger ( argument )
+
+  1. Let number be ? ToNumber(argument).
+  2. If number is NaN, return +0.
+  3. If number is +0, -0, +∞, or -∞, return number.
+  4. Return the number value that is the same sign as number
+      and whose magnitude is floor(abs(number)).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.sameValue(
+  Atomics.notify(i32a, 0, -3),
+  0,
+  'Atomics.notify(i32a, 0, -3) returns 0'
+);
+assert.sameValue(
+  Atomics.notify(i32a, 0, Number.POSITIVE_INFINITY),
+  0,
+  'Atomics.notify(i32a, 0, Number.POSITIVE_INFINITY) returns 0'
+);
+assert.sameValue(
+  Atomics.notify(i32a, 0, undefined),
+  0,
+  'Atomics.notify(i32a, 0, undefined) returns 0'
+);
+assert.sameValue(
+  Atomics.notify(i32a, 0, '33'),
+  0,
+  'Atomics.notify(i32a, 0, \'33\') returns 0'
+);
+assert.sameValue(
+  Atomics.notify(i32a, 0, { valueOf: 8 }),
+  0,
+  'Atomics.notify(i32a, 0, {valueOf: 8}) returns 0'
+);
+assert.sameValue(
+  Atomics.notify(i32a, 0),
+  0,
+  'Atomics.notify(i32a, 0) returns 0'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-missing.js b/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-missing.js
new file mode 100644
index 0000000000..4adc0b6ccb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-missing.js
@@ -0,0 +1,69 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Default to +Infinity when missing 'count' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  ...
+  3. If count is undefined, let c be +∞.
+  ...
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 0; // Index to notify agent has started.
+const WAIT_INDEX = 1; // Index all agents are waiting on.
+const BUFFER_SIZE = 2;
+
+const NUMAGENT = 4; // Total number of agents started
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Wait until restarted by main thread.
+      var status = Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+
+      // Report wait status and then exit the agent.
+      var name = String.fromCharCode(0x41 + ${i}); // "A", "B", "C", or "D"
+      $262.agent.report(name + " " + status);
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// An agent may have been interrupted between reporting its initial report
+// and the `Atomics.wait` call. Try to yield control to ensure the agent
+// actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, WAIT_INDEX /*, count missing */), NUMAGENT,
+                 'Atomics.notify(i32a, WAIT_INDEX /*, count missing */) returns the value of `NUMAGENT`');
+
+const reports = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+assert.sameValue(reports[2], 'C ok', 'The value of reports[2] is "C ok"');
+assert.sameValue(reports[3], 'D ok', 'The value of reports[3] is "D ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-undefined.js b/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-undefined.js
new file mode 100644
index 0000000000..6c08c10151
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-defaults-to-infinity-undefined.js
@@ -0,0 +1,67 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Undefined count arg should result in an infinite count
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  3.If count is undefined, let c be +∞.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 0; // Index to notify agent has started.
+const WAIT_INDEX = 1; // Index all agents are waiting on.
+const BUFFER_SIZE = 2;
+
+const NUMAGENT = 4; // Total number of agents started
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Wait until restarted by main thread.
+      var status = Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+
+      // Report wait status and then exit the agent.
+      var name = String.fromCharCode(0x41 + ${i}); // "A", "B", "C", or "D"
+      $262.agent.report(name + " " + status);
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// An agent may have been interrupted between reporting its initial report
+// and the `Atomics.wait` call. Try to yield control to ensure the agent
+// actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, WAIT_INDEX, undefined), NUMAGENT,
+                 'Atomics.notify(i32a, WAIT_INDEX, undefined) returns the value of `NUMAGENT`');
+
+const reports = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+assert.sameValue(reports[2], 'C ok', 'The value of reports[2] is "C ok"');
+assert.sameValue(reports[3], 'D ok', 'The value of reports[3] is "D ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-from-nans.js b/js/src/tests/test262/built-ins/Atomics/notify/count-from-nans.js
new file mode 100644
index 0000000000..f80d19858e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-from-nans.js
@@ -0,0 +1,36 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  NaNs are converted to 0 for 'count' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  ...
+  3. If count is undefined, let c be +∞.
+  4. Else,
+    a. Let intCount be ? ToInteger(count).
+  ...
+
+  ToInteger ( argument )
+
+  ...
+  2. If number is NaN, return +0.
+  ...
+
+includes: [nans.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+NaNs.forEach(nan => {
+  assert.sameValue(Atomics.notify(i32a, 0, nan), 0, 'Atomics.notify(i32a, 0, nan) returns 0');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-symbol-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/count-symbol-throws.js
new file mode 100644
index 0000000000..067e802544
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-symbol-throws.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Return abrupt when symbol passed for 'count' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  ...
+  3. If count is undefined, let c be +∞.
+  4. Else,
+    a. Let intCount be ? ToInteger(count).
+  ...
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.throws(TypeError, function() {
+  Atomics.notify(i32a, 0, Symbol());
+}, '`Atomics.notify(i32a, 0, Symbol())` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/count-tointeger-throws-then-wake-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/count-tointeger-throws-then-wake-throws.js
new file mode 100644
index 0000000000..69c3c39d09
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/count-tointeger-throws-then-wake-throws.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Return abrupt when ToInteger throws an exception on 'count' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  ...
+  3. If count is undefined, let c be +∞.
+  4. Else,
+    a. Let intCount be ? ToInteger(count).
+  ...
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i32a, 0, poisoned);
+}, '`Atomics.notify(i32a, 0, poisoned)` throws Test262Error');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/descriptor.js b/js/src/tests/test262/built-ins/Atomics/notify/descriptor.js
new file mode 100644
index 0000000000..d293ca94c6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: Testing descriptor property of Atomics.notify
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'notify', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/length.js b/js/src/tests/test262/built-ins/Atomics/notify/length.js
new file mode 100644
index 0000000000..24a3571af5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Atomics.notify.length is 3.
+info: |
+  Atomics.notify ( ia, index, count )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.notify, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/name.js b/js/src/tests/test262/built-ins/Atomics/notify/name.js
new file mode 100644
index 0000000000..438e54a04d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Atomics.notify.name is "notify".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.notify, 'name', {
+  value: 'notify',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/negative-count.js b/js/src/tests/test262/built-ins/Atomics/notify/negative-count.js
new file mode 100644
index 0000000000..3707422f20
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/negative-count.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies zero waiters if the count is negative
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.long;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 0, ${TIMEOUT}));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0, -1), 0, 'Atomics.notify(i32a, 0, -1) returns 0'); // Don't actually notify it
+
+assert.sameValue($262.agent.getReport(), 'timed-out', '$262.agent.getReport() returns "timed-out"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/negative-index-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/negative-index-throws.js
new file mode 100644
index 0000000000..7b22715ce6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/negative-index-throws.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a RangeError is index < 0
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+        ...
+        2.b If integerIndex < 0, throw a RangeError exception
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, -Infinity, poisoned);
+}, '`Atomics.notify(i32a, -Infinity, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, -7.999, poisoned);
+}, '`Atomics.notify(i32a, -7.999, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, -1, poisoned);
+}, '`Atomics.notify(i32a, -1, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, -300, poisoned);
+}, '`Atomics.notify(i32a, -300, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-int32-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/non-int32-typedarray-throws.js
new file mode 100644
index 0000000000..5ca1ab5080
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-int32-typedarray-throws.js
@@ -0,0 +1,90 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a TypeError if typedArray arg is not an Int32Array
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      5.If onlyInt32 is true, then
+        If typeName is not "Int32Array", throw a TypeError exception.
+features: [Atomics, Float32Array, Float64Array, Int8Array, TypedArray, Uint16Array, Uint8Array, Uint8ClampedArray]
+---*/
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  const view = new Float64Array(
+    new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Float64Array( new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Float32Array(
+    new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Float32Array( new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+if (typeof Float16Array !== 'undefined') {
+  assert.throws(TypeError, function() {
+    const view = new Float16Array(
+      new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2)
+    );
+    Atomics.notify(view, poisoned, poisoned);
+  }, '`const view = new Float16Array( new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+}
+
+assert.throws(TypeError, function() {
+  const view = new Int16Array(
+    new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Int16Array( new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Int8Array(
+    new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Int8Array( new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint32Array(
+    new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.notify(new Uint32Array(),  poisoned, poisoned);
+}, '`const view = new Uint32Array( new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4) ); Atomics.notify(new Uint32Array(), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint16Array(
+    new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Uint16Array( new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint8Array(
+    new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Uint8Array( new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint8ClampedArray(
+    new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT)
+  );
+  Atomics.notify(view, poisoned, poisoned);
+}, '`const view = new Uint8ClampedArray( new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT) ); Atomics.notify(view, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-count-evaluation-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-count-evaluation-throws.js
new file mode 100644
index 0000000000..c745669449
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-count-evaluation-throws.js
@@ -0,0 +1,39 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Evaluates count before returning 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+  Else,
+    Let intCount be ? ToInteger(count).
+    Let c be max(intCount, 0).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i32a, 0, poisoned);
+}, '`Atomics.notify(i32a, 0, poisoned)` throws Test262Error');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-index-evaluation-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-index-evaluation-throws.js
new file mode 100644
index 0000000000..d2cda0718b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-index-evaluation-throws.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Evaluates index before returning 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  Let i be ? ValidateAtomicAccess(typedArray, index).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i32a, poisoned, 0);
+}, '`Atomics.notify(i32a, poisoned, 0)` throws Test262Error');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-non-shared-int-views-throws.js
new file mode 100644
index 0000000000..9f9ebd1bb8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-non-shared-int-views-throws.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Atomics.notify throws on non-shared integer TypedArrays
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const nonsab = new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Int16Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Int16Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Int8Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Int8Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint32Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint32Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint16Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint16Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint8Array(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint8Array(nonsab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint8ClampedArray(nonsab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint8ClampedArray(nonsab), poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-returns-0.js b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-returns-0.js
new file mode 100644
index 0000000000..5578c67b0c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-bufferdata-returns-0.js
@@ -0,0 +1,26 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Returns 0, when TA.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+  If IsSharedArrayBuffer(buffer) is false, return 0.
+
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.sameValue(Atomics.notify(i32a, 0, 0), 0, 'Atomics.notify(i32a, 0, 0) returns 0');
+assert.sameValue(Atomics.notify(i32a, 0, 1), 0, 'Atomics.notify(i32a, 0, 1) returns 0');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-shared-int-views.js b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-int-views.js
new file mode 100644
index 0000000000..4cb606a813
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-shared-int-views.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test Atomics.notify on non-shared integer TypedArrays
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Int16Array(sab), poisoned, poisoned);
+}, '`Atomics.notify(new Int16Array(sab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Int8Array(sab), poisoned, poisoned);
+}, '`Atomics.notify(new Int8Array(sab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint32Array(sab),  poisoned, poisoned);
+}, '`Atomics.notify(new Uint32Array(sab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint16Array(sab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint16Array(sab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint8Array(sab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint8Array(sab), poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(new Uint8ClampedArray(sab), poisoned, poisoned);
+}, '`Atomics.notify(new Uint8ClampedArray(sab), poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/non-views.js b/js/src/tests/test262/built-ins/Atomics/notify/non-views.js
new file mode 100644
index 0000000000..e068c2d5c7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test Atomics.notify on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(nonView) {
+  assert.throws(TypeError, function() {
+    Atomics.notify(nonView, 0, 0);
+  }, '`Atomics.notify(nonView, 0, 0)` throws TypeError'); // Even with count == 0
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/notify/not-a-constructor.js
new file mode 100644
index 0000000000..fd1cbdce47
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.notify does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.notify), false, 'isConstructor(Atomics.notify) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/not-a-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/not-a-typedarray-throws.js
new file mode 100644
index 0000000000..5f9b7e2b08
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/not-a-typedarray-throws.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a TypeError if the typedArray arg is not a TypedArray object
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      3.If typedArray does not have a [[TypedArrayName]] internal slot, throw a TypeError exception.
+
+features: [Atomics]
+---*/
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait({}, 0, 0, 0);
+}, '`Atomics.wait({}, 0, 0, 0)` throws TypeError');
+
+assert.throws(TypeError, function () {
+  Atomics.wait({}, poisoned, poisoned, poisoned);
+}, '`Atomics.wait({}, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/not-an-object-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/not-an-object-throws.js
new file mode 100644
index 0000000000..c8ca4b2a7f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/not-an-object-throws.js
@@ -0,0 +1,51 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a TypeError if typedArray arg is not an Object
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+    2. if Type(typedArray) is not Object, throw a TypeError exception
+features: [Atomics, Symbol]
+---*/
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.notify(null, poisoned, poisoned);
+}, '`Atomics.notify(null, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(undefined, poisoned, poisoned);
+}, '`Atomics.notify(undefined, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(true, poisoned, poisoned);
+}, '`Atomics.notify(true, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(false, poisoned, poisoned);
+}, '`Atomics.notify(false, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify('***string***', poisoned, poisoned);
+}, '`Atomics.notify(\'***string***\', poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(Number.NEGATIVE_INFINITY, poisoned, poisoned);
+}, '`Atomics.notify(Number.NEGATIVE_INFINITY, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(Symbol('***symbol***'), poisoned, poisoned);
+}, '`Atomics.notify(Symbol(\'***symbol***\'), poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-all-on-loc.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-all-on-loc.js
new file mode 100644
index 0000000000..a66b6ce95e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-all-on-loc.js
@@ -0,0 +1,92 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies all waiters on a location, but does not
+  notify waiters on other locations.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Waiters on this will be woken
+const WAIT_FAKE = 1;              // Waiters on this will not be woken
+const RUNNING = 2;                // Accounting of live agents
+const NOTIFY_INDEX = 3;             // Accounting for too early timeouts
+const NUMAGENT = 3;
+const TIMEOUT_AGENT_MESSAGES = 2; // Number of messages for the timeout agent
+const BUFFER_SIZE = 4;
+
+// Long timeout to ensure the agent doesn't timeout before the main agent calls
+// `Atomics.notify`.
+const TIMEOUT = $262.agent.timeouts.long;
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      $262.agent.report("A " + Atomics.wait(i32a, ${WAIT_INDEX}, 0));
+      $262.agent.leaving();
+    });
+  `);
+}
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // This will always time out.
+    $262.agent.report("B " + Atomics.wait(i32a, ${WAIT_FAKE}, 0, ${TIMEOUT}));
+
+    // If this value is not 1, then the agent timeout before the main agent
+    // called Atomics.notify.
+    const result = Atomics.load(i32a, ${NOTIFY_INDEX}) === 1
+                   ? "timeout after Atomics.notify"
+                   : "timeout before Atomics.notify";
+    $262.agent.report("W " + result);
+
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT + 1);
+
+// Try to yield control to ensure the agent actually started to wait. If we
+// don't, we risk sending the notification before agents are sleeping, and we hang.
+$262.agent.tryYield();
+
+// Notify all waiting on WAIT_INDEX, should be 3 always, they won't time out.
+assert.sameValue(
+  Atomics.notify(i32a, WAIT_INDEX),
+  NUMAGENT,
+  'Atomics.notify(i32a, WAIT_INDEX) returns the value of `NUMAGENT`'
+);
+
+Atomics.store(i32a, NOTIFY_INDEX, 1);
+
+const reports = [];
+for (var i = 0; i < NUMAGENT + TIMEOUT_AGENT_MESSAGES; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(reports[i], "A ok", 'The value of reports[i] is "A ok"');
+}
+assert.sameValue(reports[NUMAGENT], "B timed-out", 'The value of reports[NUMAGENT] is "B timed-out"');
+assert.sameValue(reports[NUMAGENT + 1], "W timeout after Atomics.notify",
+                 'The value of reports[NUMAGENT + 1] is "W timeout after Atomics.notify"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-all.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-all.js
new file mode 100644
index 0000000000..561833c517
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-all.js
@@ -0,0 +1,54 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies all waiters if that's what the count is.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Waiters on this will be woken
+const RUNNING = 1;                // Accounting of live agents
+const NUMAGENT = 3;
+const BUFFER_SIZE = 4;
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      $262.agent.report("A " + Atomics.wait(i32a, ${WAIT_INDEX}, 0));
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agent actually started to wait. If we
+// don't, we risk sending the notification before agents are sleeping, and we hang.
+$262.agent.tryYield();
+
+// Notify all waiting on WAIT_INDEX, should be 3 always, they won't time out.
+assert.sameValue(
+  Atomics.notify(i32a, WAIT_INDEX),
+  NUMAGENT,
+  'Atomics.notify(i32a, WAIT_INDEX) returns the value of `NUMAGENT`'
+);
+
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue($262.agent.getReport(), 'A ok', 'The value of reports[i] is "A ok"');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order-one-time.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order-one-time.js
new file mode 100644
index 0000000000..1787aa05a7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order-one-time.js
@@ -0,0 +1,82 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies agents in the order they are waiting.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const NUMAGENT = 3;
+const WAIT_INDEX = 0;             // Waiters on this will be woken
+const SPIN = 1;                   // Worker i (zero-based) spins on location SPIN+i
+const RUNNING = SPIN + NUMAGENT;  // Accounting of live agents
+const BUFFER_SIZE = RUNNING + 1;
+
+// Create workers and start them all spinning.  We set atomic slots to make
+// them go into a wait, thus controlling the waiting order.  Then we notify them
+// one by one and observe the notification order.
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      while (Atomics.load(i32a, ${SPIN + i}) === 0) {
+        /* nothing */
+      }
+
+      $262.agent.report(${i});
+      Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+      $262.agent.report(${i});
+
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+var waiterlist = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(
+    Atomics.store(i32a, SPIN + i, 1),
+    1,
+    `Atomics.store(i32a, SPIN + ${i}, 1) returns 1`
+  );
+
+  waiterlist.push($262.agent.getReport());
+
+  // Try to yield control to ensure the agent actually started to wait.
+  $262.agent.tryYield();
+}
+
+var notified = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(
+    Atomics.notify(i32a, WAIT_INDEX, 1),
+    1,
+    `Atomics.notify(i32a, WAIT_INDEX, 1) returns 1 (${i})`
+  );
+
+  notified.push($262.agent.getReport());
+}
+
+assert.sameValue(
+  notified.join(''),
+  waiterlist.join(''),
+  'notified.join(\'\') returns waiterlist.join(\'\')'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order.js
new file mode 100644
index 0000000000..1787aa05a7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-in-order.js
@@ -0,0 +1,82 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies agents in the order they are waiting.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const NUMAGENT = 3;
+const WAIT_INDEX = 0;             // Waiters on this will be woken
+const SPIN = 1;                   // Worker i (zero-based) spins on location SPIN+i
+const RUNNING = SPIN + NUMAGENT;  // Accounting of live agents
+const BUFFER_SIZE = RUNNING + 1;
+
+// Create workers and start them all spinning.  We set atomic slots to make
+// them go into a wait, thus controlling the waiting order.  Then we notify them
+// one by one and observe the notification order.
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      while (Atomics.load(i32a, ${SPIN + i}) === 0) {
+        /* nothing */
+      }
+
+      $262.agent.report(${i});
+      Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+      $262.agent.report(${i});
+
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+var waiterlist = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(
+    Atomics.store(i32a, SPIN + i, 1),
+    1,
+    `Atomics.store(i32a, SPIN + ${i}, 1) returns 1`
+  );
+
+  waiterlist.push($262.agent.getReport());
+
+  // Try to yield control to ensure the agent actually started to wait.
+  $262.agent.tryYield();
+}
+
+var notified = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue(
+    Atomics.notify(i32a, WAIT_INDEX, 1),
+    1,
+    `Atomics.notify(i32a, WAIT_INDEX, 1) returns 1 (${i})`
+  );
+
+  notified.push($262.agent.getReport());
+}
+
+assert.sameValue(
+  notified.join(''),
+  waiterlist.join(''),
+  'notified.join(\'\') returns waiterlist.join(\'\')'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-nan.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-nan.js
new file mode 100644
index 0000000000..5c19b62b15
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-nan.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.nofity nofities zero waiters if the count is NaN
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.long;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 0, ${TIMEOUT})); // We will timeout eventually
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0, NaN), 0, 'Atomics.notify(i32a, 0, NaN) returns 0');
+
+// Try to sleep past the timeout.
+$262.agent.trySleep(TIMEOUT);
+
+assert.sameValue($262.agent.getReport(), 'timed-out', '$262.agent.getReport() returns "timed-out"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-one.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-one.js
new file mode 100644
index 0000000000..b8b9e835c2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-one.js
@@ -0,0 +1,72 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies one waiter if that's what the count is.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Agents wait here
+const RUNNING = 1;                // Accounting of live agents here
+const NOTIFYCOUNT = 1;
+const NUMAGENT = 3;
+const BUFFER_SIZE = 4;
+
+const TIMEOUT = $262.agent.timeouts.long;
+
+for (var i = 0; i < NUMAGENT; i++ ) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Waiters that are not woken will time out eventually.
+      $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+// There's a slight risk we'll fail to notify the desired count, if the preceding
+// tryYield() took much longer than anticipated and workers have started timing
+// out.
+assert.sameValue(
+  Atomics.notify(i32a, 0, NOTIFYCOUNT),
+  NOTIFYCOUNT,
+  'Atomics.notify(i32a, 0, NOTIFYCOUNT) returns the value of `NOTIFYCOUNT`'
+);
+
+// Try to sleep past the timeout.
+$262.agent.trySleep(TIMEOUT);
+
+// Collect and check results
+const reports = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+for (var i = 0; i < NOTIFYCOUNT; i++) {
+  assert.sameValue(reports[i], 'ok', 'The value of reports[i] is "ok"');
+}
+for (var i = NOTIFYCOUNT; i < NUMAGENT; i++) {
+  assert.sameValue(reports[i], 'timed-out', 'The value of reports[i] is "timed-out"');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-renotify-noop.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-renotify-noop.js
new file mode 100644
index 0000000000..40f36bd030
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-renotify-noop.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify on awoken waiter is a noop.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.long;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 0, ${TIMEOUT}));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0, 1), 1, 'Atomics.notify(i32a, 0, 1) returns 1');
+
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+// Already notified, this should be a noop
+assert.sameValue(Atomics.notify(i32a, 0, 1), 0, 'Atomics.notify(i32a, 0, 1) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-two.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-two.js
new file mode 100644
index 0000000000..e218a5f3f7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-two.js
@@ -0,0 +1,72 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies two waiters if that's what the count is.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Agents wait here
+const RUNNING = 1;                // Accounting of live agents here
+const NOTIFYCOUNT = 2;
+const NUMAGENT = 3;
+const BUFFER_SIZE = 4;
+
+const TIMEOUT = $262.agent.timeouts.long;
+
+for (var i = 0; i < NUMAGENT; i++ ) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Waiters that are not woken will time out eventually.
+      $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+      $262.agent.leaving();
+    })
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+// There's a slight risk we'll fail to notify the desired count, if the preceding
+// tryYield() took much longer than anticipated and workers have started timing
+// out.
+assert.sameValue(
+  Atomics.notify(i32a, 0, NOTIFYCOUNT),
+  NOTIFYCOUNT,
+  'Atomics.notify(i32a, 0, NOTIFYCOUNT) returns the value of `NOTIFYCOUNT`'
+);
+
+// Try to sleep past the timeout.
+$262.agent.trySleep(TIMEOUT);
+
+// Collect and check results
+const reports = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+for (var i = 0; i < NOTIFYCOUNT; i++) {
+  assert.sameValue(reports[i], 'ok', 'The value of reports[i] is "ok"');
+}
+for (var i = NOTIFYCOUNT; i < NUMAGENT; i++) {
+  assert.sameValue(reports[i], 'timed-out', 'The value of reports[i] is "timed-out"');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-agents-waiting.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-agents-waiting.js
new file mode 100644
index 0000000000..c0fbacaf8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-agents-waiting.js
@@ -0,0 +1,34 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies zero waiters if there are no agents waiting.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    // THIS WILL NEVER WAIT.
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// There are ZERO agents waiting to notify...
+assert.sameValue(Atomics.notify(i32a, 0, 1), 0, 'Atomics.notify(i32a, 0, 1) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-matching-agents-waiting.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-matching-agents-waiting.js
new file mode 100644
index 0000000000..7575bcb1c9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-with-no-matching-agents-waiting.js
@@ -0,0 +1,34 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies zero waiters if there are no waiters
+  at the index specified.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 0;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// There are ZERO matching agents waiting on index 1
+assert.sameValue(Atomics.notify(i32a, 1, 1), 0, 'Atomics.notify(i32a, 1, 1) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/notify-zero.js b/js/src/tests/test262/built-ins/Atomics/notify/notify-zero.js
new file mode 100644
index 0000000000..87053ac73d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/notify-zero.js
@@ -0,0 +1,59 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Test that Atomics.notify notifies zero waiters if that's what the count is.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0;             // Agents wait here
+const RUNNING = 1;                // Accounting of live agents here
+const NOTIFYCOUNT = 0;
+const NUMAGENT = 3;
+const BUFFER_SIZE = 4;
+
+const TIMEOUT = $262.agent.timeouts.long;
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Waiters that are not woken will time out eventually.
+      $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * BUFFER_SIZE)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait for agents to be running.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT),
+  NOTIFYCOUNT,
+  'Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT) returns the value of `NOTIFYCOUNT`'
+);
+
+// Try to sleep past the timeout.
+$262.agent.trySleep(TIMEOUT);
+
+for (var i = 0; i < NUMAGENT; i++) {
+  assert.sameValue($262.agent.getReport(), 'timed-out', '$262.agent.getReport() returns "timed-out"');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/null-bufferdata-throws.js
new file mode 100644
index 0000000000..f6594d3331
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/null-bufferdata-throws.js
@@ -0,0 +1,46 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.notify
+description: >
+  A null value for bufferData (detached) throws a TypeError
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+
+    Let buffer be ? ValidateTypedArray(typedArray).
+    ...
+
+      If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
+      ...
+
+        If arrayBuffer.[[ArrayBufferData]] is null, return true.
+
+includes: [detachArrayBuffer.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i32a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.notify(i32a, poisoned, poisoned);
+}, '`Atomics.notify(i32a, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/out-of-range-index-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/out-of-range-index-throws.js
new file mode 100644
index 0000000000..cc64555b1e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/out-of-range-index-throws.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Throws a RangeError if value of index arg is out of range
+  info: |
+  Atomics.notify( typedArray, index, count )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+    2.Let accessIndex be ? ToIndex(requestIndex).
+    ...
+    5. If accessIndex ≥ length, throw a RangeError exception.
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+var poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, Infinity, poisoned);
+}, '`Atomics.notify(i32a, Infinity, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, 4, poisoned);
+}, '`Atomics.notify(i32a, 4, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.notify(i32a, 200, poisoned);
+}, '`Atomics.notify(i32a, 200, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/shell.js b/js/src/tests/test262/built-ins/Atomics/notify/shell.js
new file mode 100644
index 0000000000..36d8753471
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/shell.js
@@ -0,0 +1,392 @@
+// GENERATED, DO NOT EDIT
+// file: atomicsHelper.js
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: >
+    Collection of functions used to interact with Atomics.* operations across agent boundaries.
+defines:
+  - $262.agent.getReportAsync
+  - $262.agent.getReport
+  - $262.agent.safeBroadcastAsync
+  - $262.agent.safeBroadcast
+  - $262.agent.setTimeout
+  - $262.agent.tryYield
+  - $262.agent.trySleep
+---*/
+
+/**
+ * @return {String} A report sent from an agent.
+ */
+{
+  // This is only necessary because the original
+  // $262.agent.getReport API was insufficient.
+  //
+  // All runtimes currently have their own
+  // $262.agent.getReport which is wrong, so we
+  // will pave over it with a corrected version.
+  //
+  // Binding $262.agent is necessary to prevent
+  // breaking SpiderMonkey's $262.agent.getReport
+  let getReport = $262.agent.getReport.bind($262.agent);
+
+  $262.agent.getReport = function() {
+    var r;
+    while ((r = getReport()) == null) {
+      $262.agent.sleep(1);
+    }
+    return r;
+  };
+
+  if (this.setTimeout === undefined) {
+    (function(that) {
+      that.setTimeout = function(callback, delay) {
+        let p = Promise.resolve();
+        let start = Date.now();
+        let end = start + delay;
+        function check() {
+          if ((end - Date.now()) > 0) {
+            p.then(check);
+          }
+          else {
+            callback();
+          }
+        }
+        p.then(check);
+      }
+    })(this);
+  }
+
+  $262.agent.setTimeout = setTimeout;
+
+  $262.agent.getReportAsync = function() {
+    return new Promise(function(resolve) {
+      (function loop() {
+        let result = getReport();
+        if (!result) {
+          setTimeout(loop, 1000);
+        } else {
+          resolve(result);
+        }
+      })();
+    });
+  };
+}
+
+/**
+ *
+ * Share a given Int32Array or BigInt64Array to all running agents. Ensure that the
+ * provided TypedArray is a "shared typed array".
+ *
+ * NOTE: Migrating all tests to this API is necessary to prevent tests from hanging
+ * indefinitely when a SAB is sent to a worker but the code in the worker attempts to
+ * create a non-sharable TypedArray (something that is not Int32Array or BigInt64Array).
+ * When that scenario occurs, an exception is thrown and the agent worker can no
+ * longer communicate with any other threads that control the SAB. If the main
+ * thread happens to be spinning in the $262.agent.waitUntil() while loop, it will never
+ * meet its termination condition and the test will hang indefinitely.
+ *
+ * Because we've defined $262.agent.broadcast(SAB) in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md, there are host implementations
+ * that assume compatibility, which must be maintained.
+ *
+ *
+ * $262.agent.safeBroadcast(TA) should not be included in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md
+ *
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ */
+$262.agent.safeBroadcast = function(typedArray) {
+  let Constructor = Object.getPrototypeOf(typedArray).constructor;
+  let temp = new Constructor(
+    new SharedArrayBuffer(Constructor.BYTES_PER_ELEMENT)
+  );
+  try {
+    // This will never actually wait, but that's fine because we only
+    // want to ensure that this typedArray CAN be waited on and is shareable.
+    Atomics.wait(temp, 0, Constructor === Int32Array ? 1 : BigInt(1));
+  } catch (error) {
+    throw new Test262Error(`${Constructor.name} cannot be used as a shared typed array. (${error})`);
+  }
+
+  $262.agent.broadcast(typedArray.buffer);
+};
+
+$262.agent.safeBroadcastAsync = async function(ta, index, expected) {
+  await $262.agent.broadcast(ta.buffer);
+  await $262.agent.waitUntil(ta, index, expected);
+  await $262.agent.tryYield();
+  return await Atomics.load(ta, index);
+};
+
+
+/**
+ * With a given Int32Array or BigInt64Array, wait until the expected number of agents have
+ * reported themselves by calling:
+ *
+ *    Atomics.add(typedArray, index, 1);
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ * @param {number} index    The index of which all agents will report.
+ * @param {number} expected The number of agents that are expected to report as active.
+ */
+$262.agent.waitUntil = function(typedArray, index, expected) {
+
+  var agents = 0;
+  while ((agents = Atomics.load(typedArray, index)) !== expected) {
+    /* nothing */
+  }
+  assert.sameValue(agents, expected, "Reporting number of 'agents' equals the value of 'expected'");
+};
+
+/**
+ * Timeout values used throughout the Atomics tests. All timeouts are specified in milliseconds.
+ *
+ * @property {number} yield Used for `$262.agent.tryYield`. Must not be used in other functions.
+ * @property {number} small Used when agents will always timeout and `Atomics.wake` is not part
+ *                          of the test semantics. Must be larger than `$262.agent.timeouts.yield`.
+ * @property {number} long  Used when some agents may timeout and `Atomics.wake` is called on some
+ *                          agents. The agents are required to wait and this needs to be observable
+ *                          by the main thread.
+ * @property {number} huge  Used when `Atomics.wake` is called on all waiting agents. The waiting
+ *                          must not timeout. The agents are required to wait and this needs to be
+ *                          observable by the main thread. All waiting agents must be woken by the
+ *                          main thread.
+ *
+ * Usage for `$262.agent.timeouts.small`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const TIMEOUT = $262.agent.timeouts.small;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agent was started and then try to yield control to increase
+ *   // the likelihood the agent has called `Atomics.wait` and is now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // The agent is expected to time out.
+ *   assert.sameValue($262.agent.getReport(), "timed-out");
+ *
+ *
+ * Usage for `$262.agent.timeouts.long`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.long;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake exactly one agent.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX, 1), 1);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until exactly one agent was woken.
+ *   // var woken = 0;
+ *   // while ((woken = Atomics.wake(i32a, WAIT_INDEX, 1)) !== 0) ;
+ *   // assert.sameValue(woken, 1);
+ *
+ *   // One agent was woken and the other one timed out.
+ *   const reports = [$262.agent.getReport(), $262.agent.getReport()];
+ *   assert(reports.includes("ok"));
+ *   assert(reports.includes("timed-out"));
+ *
+ *
+ * Usage for `$262.agent.timeouts.huge`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.huge;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake all agents.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX), NUMAGENT);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until all agents were woken.
+ *   // for (var wokenCount = 0; wokenCount < NUMAGENT; ) {
+ *   //   var woken = 0;
+ *   //   while ((woken = Atomics.wake(i32a, WAIT_INDEX)) !== 0) ;
+ *   //   // Maybe perform an action on the woken agents here.
+ *   //   wokenCount += woken;
+ *   // }
+ *
+ *   // All agents were woken and none timeout.
+ *   for (var i = 0; i < NUMAGENT; i++) {
+ *     assert($262.agent.getReport(), "ok");
+ *   }
+ */
+$262.agent.timeouts = {
+  yield: 100,
+  small: 200,
+  long: 1000,
+  huge: 10000,
+};
+
+/**
+ * Try to yield control to the agent threads.
+ *
+ * Usage:
+ *   const VALUE = 0;
+ *   const RUNNING = 1;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       Atomics.store(i32a, ${VALUE}, 1);
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until agent was started and then try to yield control.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // Note: This result is not guaranteed, but should hold in practice most of the time.
+ *   assert.sameValue(Atomics.load(i32a, VALUE), 1);
+ *
+ * The default implementation simply waits for `$262.agent.timeouts.yield` milliseconds.
+ */
+$262.agent.tryYield = function() {
+  $262.agent.sleep($262.agent.timeouts.yield);
+};
+
+/**
+ * Try to sleep the current agent for the given amount of milliseconds. It is acceptable,
+ * but not encouraged, to ignore this sleep request and directly continue execution.
+ *
+ * The default implementation calls `$262.agent.sleep(ms)`.
+ *
+ * @param {number} ms Time to sleep in milliseconds.
+ */
+$262.agent.trySleep = function(ms) {
+  $262.agent.sleep(ms);
+};
+
+// file: detachArrayBuffer.js
+// Copyright (C) 2016 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A function used in the process of asserting correctness of TypedArray objects.
+
+    $262.detachArrayBuffer is defined by a host.
+defines: [$DETACHBUFFER]
+---*/
+
+function $DETACHBUFFER(buffer) {
+  if (!$262 || typeof $262.detachArrayBuffer !== "function") {
+    throw new Test262Error("No method available to detach an ArrayBuffer");
+  }
+  $262.detachArrayBuffer(buffer);
+}
+
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
+
+// file: nans.js
+// Copyright (C) 2016 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A collection of NaN values produced from expressions that have been observed
+    to create distinct bit representations on various platforms. These provide a
+    weak basis for assertions regarding the consistent canonicalization of NaN
+    values in Array buffers.
+defines: [NaNs]
+---*/
+
+var NaNs = [
+  NaN,
+  Number.NaN,
+  NaN * 0,
+  0/0,
+  Infinity/Infinity,
+  -(0/0),
+  Math.pow(-1, 0.5),
+  -Math.pow(-1, 0.5),
+  Number("Not-a-Number"),
+];
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/symbol-for-index-throws.js b/js/src/tests/test262/built-ins/Atomics/notify/symbol-for-index-throws.js
new file mode 100644
index 0000000000..1a157f59c6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/symbol-for-index-throws.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  Return abrupt when ToInteger throws for 'index' argument to Atomics.notify
+info: |
+  Atomics.notify( typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i32a, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.notify(i32a, poisonedValueOf, poisonedValueOf)` throws Test262Error');
+
+assert.throws(Test262Error, function() {
+  Atomics.notify(i32a, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.notify(i32a, poisonedToPrimitive, poisonedToPrimitive)` throws Test262Error');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(i32a, Symbol("foo"), poisonedValueOf);
+}, '`Atomics.notify(i32a, Symbol("foo"), poisonedValueOf)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.notify(i32a, Symbol("foo"), poisonedToPrimitive);
+}, '`Atomics.notify(i32a, Symbol("foo"), poisonedToPrimitive)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/undefined-index-defaults-to-zero.js b/js/src/tests/test262/built-ins/Atomics/notify/undefined-index-defaults-to-zero.js
new file mode 100644
index 0000000000..a0bbca4f4e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/undefined-index-defaults-to-zero.js
@@ -0,0 +1,76 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  An undefined index arg should translate to 0
+info: |
+  Atomics.notify( typedArray, index, count )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+var WAIT_INDEX = 0;
+var RUNNING = 1;
+
+var NUMAGENT = 2;
+
+for (var i = 0; i < NUMAGENT; i++) {
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+
+      // Notify main thread that the agent was started.
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Wait until restarted by main thread.
+      var status = Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+
+      // Report wait status.
+      $262.agent.report(status);
+
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait until both agents started.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agents actually started to wait.
+$262.agent.tryYield();
+
+// Notify at index 0, undefined => 0.
+var woken = 0;
+while ((woken = Atomics.notify(i32a, undefined, 1)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i32a, undefined, 1) returns 1');
+
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+// Notify again at index 0, default => 0.
+var woken = 0;
+while ((woken = Atomics.notify(i32a /*, default values used */)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i32a /*, default values used */) returns 1');
+
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-count-coercion.js b/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-count-coercion.js
new file mode 100644
index 0000000000..6ddf964c81
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-count-coercion.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  TypedArray type is validated before `count` argument is coerced.
+info: |
+  24.4.12 Atomics.notify ( typedArray, index, count )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var count = {
+  valueOf() {
+    throw new Test262Error("count coerced");
+  }
+};
+
+var badArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (var badArrayType of badArrayTypes) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.notify(typedArray, 0, count);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..3f4b498b4e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/notify/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.12 Atomics.notify ( typedArray, index, count )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+var badArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (var badArrayType of badArrayTypes) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.notify(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bad-range.js b/js/src/tests/test262/built-ins/Atomics/or/bad-range.js
new file mode 100644
index 0000000000..eaa6285ec4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Test range checking of Atomics.or on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.or(view, IdxGen(view), 10);
+    }, '`Atomics.or(view, IdxGen(view), 10)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/or/bigint/bad-range.js
new file mode 100644
index 0000000000..9ae3dd11c0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.or
+description: >
+  Test range checking of Atomics.or on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+var buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.or(view, IdxGen(view), 10n);
+    }, '`Atomics.or(view, IdxGen(view), 10n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/or/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/or/bigint/good-views.js
new file mode 100644
index 0000000000..1332b622e8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bigint/good-views.js
@@ -0,0 +1,100 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.or
+description: Test Atomics.or on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0x33333333n;
+  control[0] = 0x33333333n;
+
+  assert.sameValue(
+    Atomics.or(view, 8, 0x55555555n),
+    control[0],
+    'Atomics.or(view, 8, 0x55555555n) returns the value of `control[0]` (0x33333333n)'
+  );
+
+  control[0] = 0x77777777n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x77777777n)'
+  );
+
+  assert.sameValue(
+    Atomics.or(view, 8, 0xF0F0F0F0n),
+    control[0],
+    'Atomics.or(view, 8, 0xF0F0F0F0n) returns the value of `control[0]` (0x77777777n)'
+  );
+
+  control[0] = 0xF7F7F7F7n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0xF7F7F7F7n)'
+  );
+
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.or(view, 3, 0n),
+    control[0],
+    'Atomics.or(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.or(view, 3, 0n),
+    control[0],
+    'Atomics.or(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.or(view, 3, 0n),
+    control[0],
+    'Atomics.or(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.or(view, Idx, 0n), 37n, 'Atomics.or(view, Idx, 0n) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/or/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..1b8642c291
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.or
+description: >
+  Atomics.or will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.or(view, 0, 1n), 0n, 'Atomics.or(view, 0, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/or/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/or/browser.js b/js/src/tests/test262/built-ins/Atomics/or/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/or/descriptor.js b/js/src/tests/test262/built-ins/Atomics/or/descriptor.js
new file mode 100644
index 0000000000..7b1cca599e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/descriptor.js
@@ -0,0 +1,17 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: Testing descriptor property of Atomics.or
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+verifyProperty(Atomics, 'or', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/or/expected-return-value.js
new file mode 100644
index 0000000000..642572a78a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/expected-return-value.js
@@ -0,0 +1,49 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Atomics.and returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.or( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, or).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const a = 0b00000001000000001000000010000001;
+const b = 0b00000001111111111000000011111111;
+const c = 0b00000001111111111000000011111111;
+
+i32a[0] = a;
+
+assert.sameValue(
+  Atomics.or(i32a, 0, b),
+  a,
+  'Atomics.or(i32a, 0, b) returns the value of `a` (0b00000001000000001000000010000001)'
+);
+
+assert.sameValue(i32a[0], c, 'The value of i32a[0] equals the value of `c` (0b00000001111111111000000011111111)');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/good-views.js b/js/src/tests/test262/built-ins/Atomics/or/good-views.js
new file mode 100644
index 0000000000..b004226bd8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/good-views.js
@@ -0,0 +1,84 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: Test Atomics.or on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var sab = new SharedArrayBuffer(1024);
+var ab = new ArrayBuffer(16);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  var view = new TA(sab, 32, 20);
+  var control = new TA(ab, 0, 2);
+
+  view[8] = 0x33333333;
+  control[0] = 0x33333333;
+  assert.sameValue(Atomics.or(view, 8, 0x55555555), control[0],
+    'Atomics.or(view, 8, 0x55555555) returns the value of `control[0]` (0x33333333)');
+
+  control[0] = 0x77777777;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x77777777)'
+  );
+  assert.sameValue(Atomics.or(view, 8, 0xF0F0F0F0), control[0],
+    'Atomics.or(view, 8, 0xF0F0F0F0) returns the value of `control[0]` (0x77777777)');
+
+  control[0] = 0xF7F7F7F7;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0xF7F7F7F7)'
+  );
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.or(view, 3, 0), control[0],
+    'Atomics.or(view, 3, 0) returns the value of `control[0]` (-5)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (-5)'
+  );
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.or(view, 3, 0), control[0],
+    'Atomics.or(view, 3, 0) returns the value of `control[0]` (12345)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (12345)'
+  );
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.or(view, 3, 0), control[0],
+    'Atomics.or(view, 3, 0) returns the value of `control[0]` (123456789)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (123456789)'
+  );
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.or(view, Idx, 0), 37, 'Atomics.or(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/length.js b/js/src/tests/test262/built-ins/Atomics/or/length.js
new file mode 100644
index 0000000000..8a9d7c30af
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Atomics.or.length is 3.
+info: |
+  Atomics.or ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.or, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/name.js b/js/src/tests/test262/built-ins/Atomics/or/name.js
new file mode 100644
index 0000000000..ff455ddb8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Atomics.or.name is "or".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.or, 'name', {
+  value: 'or',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/or/non-shared-bufferdata.js
new file mode 100644
index 0000000000..8afe735477
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Atomics.or will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.or(view, 0, 1), 0, 'Atomics.or(view, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 1, 'Atomics.load(view, 0) returns 1');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/or/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..90987ae1ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.and(view, 0, 1);
+  }, `Atomics.and(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/non-views.js b/js/src/tests/test262/built-ins/Atomics/or/non-views.js
new file mode 100644
index 0000000000..e5fe5d9079
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  Test Atomics.or on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.or(view, 0, 0);
+  }, '`Atomics.or(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/or/not-a-constructor.js
new file mode 100644
index 0000000000..8c40656b9a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.or does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.or), false, 'isConstructor(Atomics.or) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.or(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.or(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/shell.js b/js/src/tests/test262/built-ins/Atomics/or/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..1f016df232
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.8 Atomics.or ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, or).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.or(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..f94a54a843
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/or/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.or
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.8 Atomics.or ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, or).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.or(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/prop-desc.js b/js/src/tests/test262/built-ins/Atomics/prop-desc.js
new file mode 100644
index 0000000000..ffcbac8fa0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/prop-desc.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics-object
+description: >
+  Property descriptor of Atomics
+info: |
+  The Atomics Object
+
+  ...
+  The Atomics object does not have a [[Construct]] internal method;
+  it is not possible to use the Atomics object as a constructor with the new operator.
+
+  The Atomics object does not have a [[Call]] internal method;
+  it is not possible to invoke the Atomics object as a function.
+
+  17 ECMAScript Standard Built-in Objects:
+
+  Every other data property described in clauses 18 through 26 and in Annex B.2
+  has the attributes { [[Writable]]: true, [[Enumerable]]: false,
+  [[Configurable]]: true } unless otherwise specified.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+assert.sameValue(typeof Atomics, "object", 'The value of `typeof Atomics` is "object"');
+
+assert.throws(TypeError, function() {
+  Atomics();
+}, '`Atomics()` throws TypeError');
+
+assert.throws(TypeError, function() {
+  new Atomics();
+}, '`new Atomics()` throws TypeError');
+
+verifyProperty(this, "Atomics", {
+  enumerable: false,
+  writable: true,
+  configurable: true
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/proto.js b/js/src/tests/test262/built-ins/Atomics/proto.js
new file mode 100644
index 0000000000..859c451b8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/proto.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics-object
+description: >
+  The prototype of Atomics is Object.prototype
+info: |
+  The Atomics Object
+
+  The value of the [[Prototype]] internal slot of the Atomics object is the
+  intrinsic object %ObjectPrototype%.
+features: [Atomics]
+---*/
+
+assert.sameValue(
+  Object.getPrototypeOf(Atomics),
+  Object.prototype,
+  'Object.getPrototypeOf(Atomics) returns the value of `Object.prototype`'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/shell.js b/js/src/tests/test262/built-ins/Atomics/shell.js
new file mode 100644
index 0000000000..54b49ef339
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/shell.js
@@ -0,0 +1,286 @@
+// GENERATED, DO NOT EDIT
+// file: testAtomics.js
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of SharedArrayBuffer objects.
+defines:
+  - testWithAtomicsOutOfBoundsIndices
+  - testWithAtomicsInBoundsIndices
+  - testWithAtomicsNonViewValues
+---*/
+
+
+/**
+ * Calls the provided function for a each bad index that should throw a
+ * RangeError when passed to an Atomics method on a SAB-backed view where
+ * index 125 is out of range.
+ *
+ * @param f - the function to call for each bad index.
+ */
+function testWithAtomicsOutOfBoundsIndices(f) {
+  var bad_indices = [
+    function(view) { return -1; },
+    function(view) { return view.length; },
+    function(view) { return view.length * 2; },
+    function(view) { return Number.POSITIVE_INFINITY; },
+    function(view) { return Number.NEGATIVE_INFINITY; },
+    function(view) { return { valueOf: function() { return 125; } }; },
+    function(view) { return { toString: function() { return '125'; }, valueOf: false }; }, // non-callable valueOf triggers invocation of toString
+  ];
+
+  for (var i = 0; i < bad_indices.length; ++i) {
+    var IdxGen = bad_indices[i];
+    try {
+      f(IdxGen);
+    } catch (e) {
+      e.message += ' (Testing with index gen ' + IdxGen + '.)';
+      throw e;
+    }
+  }
+}
+
+/**
+ * Calls the provided function for each good index that should not throw when
+ * passed to an Atomics method on a SAB-backed view.
+ *
+ * The view must have length greater than zero.
+ *
+ * @param f - the function to call for each good index.
+ */
+function testWithAtomicsInBoundsIndices(f) {
+  // Most of these are eventually coerced to +0 by ToIndex.
+  var good_indices = [
+    function(view) { return 0/-1; },
+    function(view) { return '-0'; },
+    function(view) { return undefined; },
+    function(view) { return NaN; },
+    function(view) { return 0.5; },
+    function(view) { return '0.5'; },
+    function(view) { return -0.9; },
+    function(view) { return { password: 'qumquat' }; },
+    function(view) { return view.length - 1; },
+    function(view) { return { valueOf: function() { return 0; } }; },
+    function(view) { return { toString: function() { return '0'; }, valueOf: false }; }, // non-callable valueOf triggers invocation of toString
+  ];
+
+  for (var i = 0; i < good_indices.length; ++i) {
+    var IdxGen = good_indices[i];
+    try {
+      f(IdxGen);
+    } catch (e) {
+      e.message += ' (Testing with index gen ' + IdxGen + '.)';
+      throw e;
+    }
+  }
+}
+
+/**
+ * Calls the provided function for each value that should throw a TypeError
+ * when passed to an Atomics method as a view.
+ *
+ * @param f - the function to call for each non-view value.
+ */
+
+function testWithAtomicsNonViewValues(f) {
+  var values = [
+    null,
+    undefined,
+    true,
+    false,
+    new Boolean(true),
+    10,
+    3.14,
+    new Number(4),
+    'Hi there',
+    new Date,
+    /a*utomaton/g,
+    { password: 'qumquat' },
+    new DataView(new ArrayBuffer(10)),
+    new ArrayBuffer(128),
+    new SharedArrayBuffer(128),
+    new Error('Ouch'),
+    [1,1,2,3,5,8],
+    function(x) { return -x; },
+    Symbol('halleluja'),
+    // TODO: Proxy?
+    Object,
+    Int32Array,
+    Date,
+    Math,
+    Atomics
+  ];
+
+  for (var i = 0; i < values.length; ++i) {
+    var nonView = values[i];
+    try {
+      f(nonView);
+    } catch (e) {
+      e.message += ' (Testing with non-view value ' + nonView + '.)';
+      throw e;
+    }
+  }
+}
+
+
+// file: testTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of TypedArray objects.
+defines:
+  - floatArrayConstructors
+  - nonClampedIntArrayConstructors
+  - intArrayConstructors
+  - typedArrayConstructors
+  - TypedArray
+  - testWithTypedArrayConstructors
+  - nonAtomicsFriendlyTypedArrayConstructors
+  - testWithAtomicsFriendlyTypedArrayConstructors
+  - testWithNonAtomicsFriendlyTypedArrayConstructors
+  - testTypedArrayConversions
+---*/
+
+var floatArrayConstructors = [
+  Float64Array,
+  Float32Array
+];
+
+var nonClampedIntArrayConstructors = [
+  Int32Array,
+  Int16Array,
+  Int8Array,
+  Uint32Array,
+  Uint16Array,
+  Uint8Array
+];
+
+var intArrayConstructors = nonClampedIntArrayConstructors.concat([Uint8ClampedArray]);
+
+// Float16Array is a newer feature
+// adding it to this list unconditionally would cause implementations lacking it to fail every test which uses it
+if (typeof Float16Array !== 'undefined') {
+  floatArrayConstructors.push(Float16Array);
+}
+
+/**
+ * Array containing every non-bigint typed array constructor.
+ */
+
+var typedArrayConstructors = floatArrayConstructors.concat(intArrayConstructors);
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Callback for testing a typed array constructor.
+ *
+ * @callback typedArrayConstructorCallback
+ * @param {Function} Constructor the constructor object to test with.
+ */
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithTypedArrayConstructors(f, selected) {
+  var constructors = selected || typedArrayConstructors;
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
+
+var nonAtomicsFriendlyTypedArrayConstructors = floatArrayConstructors.concat([Uint8ClampedArray]);
+/**
+ * Calls the provided function for every non-"Atomics Friendly" typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithNonAtomicsFriendlyTypedArrayConstructors(f) {
+  testWithTypedArrayConstructors(f, nonAtomicsFriendlyTypedArrayConstructors);
+}
+
+/**
+ * Calls the provided function for every "Atomics Friendly" typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithAtomicsFriendlyTypedArrayConstructors(f) {
+  testWithTypedArrayConstructors(f, [
+    Int32Array,
+    Int16Array,
+    Int8Array,
+    Uint32Array,
+    Uint16Array,
+    Uint8Array,
+  ]);
+}
+
+/**
+ * Helper for conversion operations on TypedArrays, the expected values
+ * properties are indexed in order to match the respective value for each
+ * TypedArray constructor
+ * @param  {Function} fn - the function to call for each constructor and value.
+ *                         will be called with the constructor, value, expected
+ *                         value, and a initial value that can be used to avoid
+ *                         a false positive with an equivalent expected value.
+ */
+function testTypedArrayConversions(byteConversionValues, fn) {
+  var values = byteConversionValues.values;
+  var expected = byteConversionValues.expected;
+
+  testWithTypedArrayConstructors(function(TA) {
+    var name = TA.name.slice(0, -5);
+
+    return values.forEach(function(value, index) {
+      var exp = expected[name][index];
+      var initial = 0;
+      if (exp === 0) {
+        initial = 1;
+      }
+      fn(TA, value, exp, initial);
+    });
+  });
+}
+
+/**
+ * Checks if the given argument is one of the float-based TypedArray constructors.
+ *
+ * @param {constructor} ctor - the value to check
+ * @returns {boolean}
+ */
+function isFloatTypedArrayConstructor(arg) {
+  return floatArrayConstructors.indexOf(arg) !== -1;
+}
+
+/**
+ * Determines the precision of the given float-based TypedArray constructor.
+ *
+ * @param {constructor} ctor - the value to check
+ * @returns {string} "half", "single", or "double" for Float16Array, Float32Array, and Float64Array respectively.
+ */
+function floatTypedArrayConstructorPrecision(FA) {
+  if (typeof Float16Array !== "undefined" && FA === Float16Array) {
+    return "half";
+  } else if (FA === Float32Array) {
+    return "single";
+  } else if (FA === Float64Array) {
+    return "double";
+  } else {
+    throw new Error("Malformed test - floatTypedArrayConstructorPrecision called with non-float TypedArray");
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bad-range.js b/js/src/tests/test262/built-ins/Atomics/store/bad-range.js
new file mode 100644
index 0000000000..e383d1d9ff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Test range checking of Atomics.store on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.store(view, IdxGen(view), 10);
+    }, '`Atomics.store(view, IdxGen(view), 10)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/store/bigint/bad-range.js
new file mode 100644
index 0000000000..e7dd5520ce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.store
+description: >
+  Test range checking of Atomics.store on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(TA => {
+  const view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.store(view, IdxGen(view), 10n);
+    }, '`Atomics.store(view, IdxGen(view), 10n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/store/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/store/bigint/good-views.js
new file mode 100644
index 0000000000..c4d2dff00b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bigint/good-views.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.store
+description: Test Atomics.store on arrays that allow atomic operations.
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+// Make it interesting - use non-zero byteOffsets and non-zero indexes.
+// In-bounds boundary cases for indexing
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  const values = [
+    10n,
+    -5n,
+    12345n,
+    123456789n,
+    BigInt('33'),
+    {
+      valueOf: function() { return 33n; }
+    }
+  ];
+
+  for (let i = 0; i < values.length; i++) {
+    let val = values[i];
+    assert.sameValue(
+      Atomics.store(view, 3, val),
+      BigInt(val),
+      'Atomics.store(view, 3, val) returns BigInt(val)'
+    );
+
+    control[0] = val;
+
+    assert.sameValue(
+      view[3],
+      control[0],
+      'The value of view[3] equals the value of `control[0]` (val)'
+    );
+  }
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.load(view, Idx), 37n, 'Atomics.load(view, Idx) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/store/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..12f94006a3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.store(view, 0, 1n), 1n, 'Atomics.store(view, 0, 1n) returns 1n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/store/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/store/browser.js b/js/src/tests/test262/built-ins/Atomics/store/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/store/descriptor.js b/js/src/tests/test262/built-ins/Atomics/store/descriptor.js
new file mode 100644
index 0000000000..ea8a0e9951
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/descriptor.js
@@ -0,0 +1,17 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: Testing descriptor property of Atomics.store
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+verifyProperty(Atomics, 'store', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/expected-return-value-negative-zero.js b/js/src/tests/test262/built-ins/Atomics/store/expected-return-value-negative-zero.js
new file mode 100644
index 0000000000..fafd84cb38
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/expected-return-value-negative-zero.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store calls ToInteger, which normalizes -0 to +0
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert(
+  Object.is(
+    Atomics.store(i32a, 0, -0),
+    +0
+  ),
+  'Atomics.store(i32a, 0, -0) normalizes -0 to +0'
+);
+assert.sameValue(
+  i32a[0],
+  +0,
+  'The value of i32a[0] is normalized to +0'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/store/expected-return-value.js
new file mode 100644
index 0000000000..8e5c972cf4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/expected-return-value.js
@@ -0,0 +1,38 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store returns the newly stored value
+info: |
+  Atomics.store( typedArray, index, value )
+
+  ...
+  3. Let v be ? ToInteger(value).
+  ...
+  9. Perform SetValueInBuffer(buffer, indexedPosition,
+                              elementType, v, true, "SeqCst").
+  10. Return v.
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const update = 0b00000001000000001000000010000001;
+
+assert.sameValue(
+  Atomics.store(i32a, 0, update),
+  update,
+  'Atomics.store(i32a, 0, update) returns the value of `update` (0b00000001000000001000000010000001)'
+);
+assert.sameValue(
+  i32a[0],
+  update,
+  'The value of i32a[0] equals the value of `update` (0b00000001000000001000000010000001)'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/good-views.js b/js/src/tests/test262/built-ins/Atomics/store/good-views.js
new file mode 100644
index 0000000000..c24a7cd4c9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/good-views.js
@@ -0,0 +1,71 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: Test Atomics.store on arrays that allow atomic operations.
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+const views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+
+  const values = [
+    10,
+    -5,
+    12345,
+    123456789,
+    Math.PI,
+    "33",
+    {
+      valueOf: function() { return 33; }
+    },
+    undefined
+  ];
+
+  for (let i = 0; i < values.length; i++) {
+    let val = values[i];
+    assert.sameValue(Atomics.store(view, 3, val), ToInteger(val),
+      'Atomics.store(view, 3, val) returns ToInteger(val)');
+
+    control[0] = val;
+    assert.sameValue(
+      view[3],
+      control[0],
+      'The value of view[3] equals the value of `control[0]` (val)'
+    );
+  }
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.load(view, Idx), 37, 'Atomics.load(view, Idx) returns 37');
+  });
+}, views);
+
+function ToInteger(v) {
+  v = +v;
+  if (isNaN(v)) {
+    return 0;
+  }
+  if (v == 0 || !isFinite(v)) {
+    return v;
+  }
+  if (v < 0) {
+    return -Math.floor(Math.abs(v));
+  }
+  return Math.floor(v);
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/length.js b/js/src/tests/test262/built-ins/Atomics/store/length.js
new file mode 100644
index 0000000000..eae6e352f9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store.length is 3.
+info: |
+  Atomics.store ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.store, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/name.js b/js/src/tests/test262/built-ins/Atomics/store/name.js
new file mode 100644
index 0000000000..580ec46071
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store.name is "store".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.store, 'name', {
+  value: 'store',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/store/non-shared-bufferdata.js
new file mode 100644
index 0000000000..78f1dd9ce0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.store(view, 0, 1), 1, 'Atomics.store(view, 0, 1) returns 1');
+  assert.sameValue(Atomics.load(view, 0), 1, 'Atomics.load(view, 0) returns 1');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/store/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..3924de90d3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Atomics.store throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.store(view, 0, 1);
+  }, `Atomics.store(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/non-views.js b/js/src/tests/test262/built-ins/Atomics/store/non-views.js
new file mode 100644
index 0000000000..46e7b5e812
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  Test Atomics.store on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.store(view, 0, 0);
+  }, '`Atomics.store(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/store/not-a-constructor.js
new file mode 100644
index 0000000000..c9b126ba56
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.store does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.store), false, 'isConstructor(Atomics.store) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.store(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.store(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/shell.js b/js/src/tests/test262/built-ins/Atomics/store/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..08422c1339
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.9 Atomics.store ( typedArray, index, value )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.store(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..990d1d163e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/store/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.store
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.9 Atomics.store ( typedArray, index, value )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.store(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bad-range.js b/js/src/tests/test262/built-ins/Atomics/sub/bad-range.js
new file mode 100644
index 0000000000..7e08c03da5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Test range checking of Atomics.sub on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.sub(view, IdxGen(view), 10);
+    }, '`Atomics.sub(view, IdxGen(view), 10)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/sub/bigint/bad-range.js
new file mode 100644
index 0000000000..b0ce7d8cdc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bigint/bad-range.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.sub
+description: >
+  Test range checking of Atomics.sub on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+const buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(buffer);
+
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.sub(view, IdxGen(view), 10n);
+    }, '`Atomics.sub(view, IdxGen(view), 10n)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/sub/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/sub/bigint/good-views.js
new file mode 100644
index 0000000000..043b730e38
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bigint/good-views.js
@@ -0,0 +1,60 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.sub
+description: Test Atomics.sub on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+// Make it interesting - use non-zero byteOffsets and non-zero indexes.
+// In-bounds boundary cases for indexing
+// Atomics.store() computes an index from Idx in the same way as other
+// Atomics operations, not quite like view[Idx].
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 100n;
+  assert.sameValue(Atomics.sub(view, 8, 10n), 100n, 'Atomics.sub(view, 8, 10n) returns 100n');
+  assert.sameValue(view[8], 90n, 'The value of view[8] is 90n');
+  assert.sameValue(Atomics.sub(view, 8, -5n), 90n, 'Atomics.sub(view, 8, -5n) returns 90n');
+  assert.sameValue(view[8], 95n, 'The value of view[8] is 95');
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.sub(view, 3, 0n),
+    control[0],
+    'Atomics.sub(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.sub(view, 3, 0n),
+    control[0],
+    'Atomics.sub(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.sub(view, 3, 0n),
+    control[0],
+    'Atomics.sub(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.sub(view, Idx, 0n), 37n, 'Atomics.sub(view, Idx, 0n) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/sub/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..058c160005
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bigint/non-shared-bufferdata.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.sub will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.store(view, 0, 1n), 1n, 'Atomics.store(view, 0, 1n) returns 1n');
+  assert.sameValue(Atomics.sub(view, 0, 1n), 1n, 'Atomics.sub(view, 0, 1n) returns 1n');
+  assert.sameValue(Atomics.load(view, 0), 0n, 'Atomics.load(view, 0) returns 0n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/sub/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/browser.js b/js/src/tests/test262/built-ins/Atomics/sub/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/descriptor.js b/js/src/tests/test262/built-ins/Atomics/sub/descriptor.js
new file mode 100644
index 0000000000..72e0241b88
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: Testing descriptor property of Atomics.sub
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'sub', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/sub/expected-return-value.js
new file mode 100644
index 0000000000..b798da4a4a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/expected-return-value.js
@@ -0,0 +1,45 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.and returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.sub( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, subtract).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const update = 0b00000001000000001000000010000001;
+
+i32a[0] = update;
+
+assert.sameValue(
+  Atomics.sub(i32a, 0, update),
+  update,
+  'Atomics.sub(i32a, 0, update) returns the value of `update` (0b00000001000000001000000010000001)'
+);
+assert.sameValue(i32a[0], 0, 'The value of i32a[0] is 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/good-views.js b/js/src/tests/test262/built-ins/Atomics/sub/good-views.js
new file mode 100644
index 0000000000..60ea4ad569
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/good-views.js
@@ -0,0 +1,57 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: Test Atomics.sub on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var sab = new SharedArrayBuffer(1024);
+var ab = new ArrayBuffer(16);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  var view = new TA(sab, 32, 20);
+  var control = new TA(ab, 0, 2);
+
+  view[8] = 100;
+  assert.sameValue(Atomics.sub(view, 8, 10), 100,
+    'Atomics.sub(view, 8, 10) returns 100');
+  assert.sameValue(view[8], 90, 'The value of view[8] is 90');
+
+  assert.sameValue(Atomics.sub(view, 8, -5), 90,
+    'Atomics.sub(view, 8, -5) returns 90');
+  assert.sameValue(view[8], 95, 'The value of view[8] is 95');
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.sub(view, 3, 0), control[0],
+    'Atomics.sub(view, 3, 0) returns the value of `control[0]` (-5)');
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.sub(view, 3, 0), control[0],
+    'Atomics.sub(view, 3, 0) returns the value of `control[0]` (12345)');
+
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.sub(view, 3, 0), control[0],
+    'Atomics.sub(view, 3, 0) returns the value of `control[0]` (123456789)');
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.sub(view, Idx, 0), 37, 'Atomics.sub(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/length.js b/js/src/tests/test262/built-ins/Atomics/sub/length.js
new file mode 100644
index 0000000000..0747138634
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.sub.length is 3.
+info: |
+  Atomics.sub ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.sub, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/name.js b/js/src/tests/test262/built-ins/Atomics/sub/name.js
new file mode 100644
index 0000000000..e8aa2d3d37
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/name.js
@@ -0,0 +1,22 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.sub.name is "sub".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.sub, 'name', {
+  value: 'sub',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/sub/non-shared-bufferdata.js
new file mode 100644
index 0000000000..3f36ea5eea
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/non-shared-bufferdata.js
@@ -0,0 +1,22 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.sub will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.store(view, 0, 1), 1, 'Atomics.store(view, 0, 1) returns 1');
+  assert.sameValue(Atomics.sub(view, 0, 1), 1, 'Atomics.sub(view, 0, 1) returns 1');
+  assert.sameValue(Atomics.load(view, 0), 0, 'Atomics.load(view, 0) returns 0');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/sub/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..c2413ed30b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Atomics.sub throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(16);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.sub(view, 0, 1);
+  }, `Atomics.sub(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/non-views.js b/js/src/tests/test262/built-ins/Atomics/sub/non-views.js
new file mode 100644
index 0000000000..85ee77acff
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  Test Atomics.sub on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.sub(view, 0, 0);
+  }, '`Atomics.sub(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/sub/not-a-constructor.js
new file mode 100644
index 0000000000..74991a59dc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.sub does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.sub), false, 'isConstructor(Atomics.sub) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.sub(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.sub(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/shell.js b/js/src/tests/test262/built-ins/Atomics/sub/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..4bb9587e6d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.10 Atomics.sub ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, sub).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.sub(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..7af4d36a94
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/sub/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.sub
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.10 Atomics.sub ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, sub).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.sub(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bad-range.js b/js/src/tests/test262/built-ins/Atomics/wait/bad-range.js
new file mode 100644
index 0000000000..93175371b9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bad-range.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test range checking of Atomics.wait on arrays that allow atomic operations
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ...
+
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.wait(i32a, IdxGen(i32a), 0, 0);
+  }, '`Atomics.wait(i32a, IdxGen(i32a), 0, 0)` throws RangeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/bad-range.js
new file mode 100644
index 0000000000..c36d379406
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/bad-range.js
@@ -0,0 +1,29 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test range checking of Atomics.wait on arrays that allow atomic operations
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ...
+
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.wait(i64a, IdxGen(i64a), 0n, 0);
+  }, '`Atomics.wait(i64a, IdxGen(i64a), 0n, 0)` throws RangeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/cannot-suspend-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/cannot-suspend-throws.js
new file mode 100644
index 0000000000..212dbfddc6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/cannot-suspend-throws.js
@@ -0,0 +1,27 @@
+// |reftest| skip-if(xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- shell can block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Atomics.wait throws if agent cannot be suspended, CanBlock is false
+info: |
+  Assuming [[CanBlock]] is false for the main host.
+
+  Atomics.wait( typedArray, index, value, timeout )
+
+  ... (after args validation)
+  6. Let B be AgentCanSuspend().
+  7. If B is false, throw a TypeError exception.
+  ...
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+flags: [CanBlockIsFalse]
+---*/
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, 0, 0n, 0);
+}, '`Atomics.wait(i64a, 0, 0n, 0)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout-agent.js
new file mode 100644
index 0000000000..563064fe14
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout-agent.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf: function() {
+      return false;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      return false;
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const status1 = Atomics.wait(i64a, 0, 0n, false);
+    const status2 = Atomics.wait(i64a, 0, 0n, valueOf);
+    const status3 = Atomics.wait(i64a, 0, 0n, toPrimitive);
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.report(status3);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout.js
new file mode 100644
index 0000000000..55f46d2504
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/false-for-timeout.js
@@ -0,0 +1,52 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+features: [Atomics, BigInt, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf: function() {
+    return false;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    return false;
+  }
+};
+
+assert.sameValue(
+  Atomics.wait(i64a, 0, 0n, false),
+  "timed-out",
+  'Atomics.wait(i64a, 0, 0n, false) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i64a, 0, 0n, valueOf),
+  "timed-out",
+  'Atomics.wait(i64a, 0, 0n, valueOf) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i64a, 0, 0n, toPrimitive),
+  "timed-out",
+  'Atomics.wait(i64a, 0, 0n, toPrimitive) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/nan-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/nan-for-timeout.js
new file mode 100644
index 0000000000..5d3641d08a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/nan-for-timeout.js
@@ -0,0 +1,46 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  NaN timeout arg should result in an infinite timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4.Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report(Atomics.wait(i64a, 0, 0n, NaN));  // NaN => +Infinity
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i64a, 0), 1, 'Atomics.notify(i64a, 0) returns 1');
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-index-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-index-throws.js
new file mode 100644
index 0000000000..4d976026a1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-index-throws.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a RangeError is index < 0
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+        ...
+        2.b If integerIndex < 0, throw a RangeError exception
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8)
+);
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, -Infinity, poisoned, poisoned);
+}, '`Atomics.wait(i64a, -Infinity, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, -7.999, poisoned, poisoned);
+}, '`Atomics.wait(i64a, -7.999, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, -1, poisoned, poisoned);
+}, '`Atomics.wait(i64a, -1, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, -300, poisoned, poisoned);
+}, '`Atomics.wait(i64a, -300, poisoned, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout-agent.js
new file mode 100644
index 0000000000..4a177cb8b4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout-agent.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait times out with a negative timeout
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report(Atomics.wait(i64a, 0, 0n, -5)); // -5 => 0
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout.js
new file mode 100644
index 0000000000..ec01a23f68
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/negative-timeout.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait times out with a negative timeout
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.sameValue(
+  Atomics.wait(i64a, 0, 0n, -1),
+  "timed-out",
+  'Atomics.wait(i64a, 0, 0n, -1) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-no-operation.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-no-operation.js
new file mode 100644
index 0000000000..5f9021f73b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-no-operation.js
@@ -0,0 +1,62 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait returns the right result when it timed out and that
+  the time to time out is reasonable.
+  info: |
+    17. Let awoken be Suspend(WL, W, t).
+    18. If awoken is true, then
+      a. Assert: W is not on the list of waiters in WL.
+    19. Else,
+      a.Perform RemoveWaiter(WL, W).
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+// NO OPERATION OCCURS HERE!
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-add.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-add.js
new file mode 100644
index 0000000000..ba13f78020
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-add.js
@@ -0,0 +1,57 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Add operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.add(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-and.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-and.js
new file mode 100644
index 0000000000..da44dafd83
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-and.js
@@ -0,0 +1,57 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously nofity on index which is subject to And operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.and(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-compareExchange.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-compareExchange.js
new file mode 100644
index 0000000000..a40ec5ee9a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-compareExchange.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to compareExchange operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.compareExchange(i64a, 0, 0n, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-exchange.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-exchange.js
new file mode 100644
index 0000000000..49b49b84af
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-exchange.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to exchange operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.exchange(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-or.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-or.js
new file mode 100644
index 0000000000..c30e5856f0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-or.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Or operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.or(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-store.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-store.js
new file mode 100644
index 0000000000..aa07e3d51d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-store.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Demonstrates that Atomics.store(...) is causing a waiting
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.store(i64a, 0, 0x111111n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-sub.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-sub.js
new file mode 100644
index 0000000000..64f81f9008
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-sub.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Sub operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.sub(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-xor.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-xor.js
new file mode 100644
index 0000000000..13e7e49f3d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/no-spurious-wakeup-on-xor.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to xor operation
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.xor(i64a, 0, 1n);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i64a, 0), 0, 'Atomics.notify(i64a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-bigint64-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-bigint64-typedarray-throws.js
new file mode 100644
index 0000000000..ed42bf7849
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-bigint64-typedarray-throws.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-validatesharedintegertypedarray
+description: >
+  Throws a TypeError if typedArray arg is not a BigInt64Array
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ...
+
+
+  ValidateSharedIntegerTypedArray(typedArray [ , waitable ] )
+
+  ...
+  5. If waitable is true, then
+      a. If typeName is not "BigInt64Array",
+      throw a TypeError exception.
+
+features: [Atomics, BigInt, SharedArrayBuffer]
+---*/
+
+const i64a = new BigUint64Array(
+  new SharedArrayBuffer(BigUint64Array.BYTES_PER_ELEMENT)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, 0, 0n, 0);
+}, '`Atomics.wait(i64a, 0, 0n, 0)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(i64a, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-shared-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-shared-bufferdata-throws.js
new file mode 100644
index 0000000000..ec45720916
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/non-shared-bufferdata-throws.js
@@ -0,0 +1,34 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if typedArray.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          4.If bufferData is a Data Block, return false.
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+const i64a = new BigInt64Array(new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT));
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, 0, 0n, 0);
+}, '`Atomics.wait(i64a, 0, 0n, 0)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(i64a, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/null-bufferdata-throws.js
new file mode 100644
index 0000000000..9499b9f0e6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/null-bufferdata-throws.js
@@ -0,0 +1,48 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  A null value for bufferData throws a TypeError
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  ...
+
+  ValidateSharedIntegerTypedArray(typedArray [ , onlyInt32 ] )
+
+  ...
+  9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+
+
+  IsSharedArrayBuffer( obj )
+
+  ...
+  3.If bufferData is null, return false.
+
+includes: [detachArrayBuffer.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i64a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i64a, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(i64a, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/out-of-range-index-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/out-of-range-index-throws.js
new file mode 100644
index 0000000000..582a251abb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/out-of-range-index-throws.js
@@ -0,0 +1,40 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a RangeError if value of index arg is out of range
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+    2.Let accessIndex be ? ToIndex(requestIndex).
+    ...
+    5. If accessIndex ≥ length, throw a RangeError exception.
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, Infinity, poisoned, poisoned);
+}, '`Atomics.wait(i64a, Infinity, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, 8, poisoned, poisoned);
+}, '`Atomics.wait(i64a, 8, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i64a, 200, poisoned, poisoned);
+}, '`Atomics.wait(i64a, 200, poisoned, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/shell.js
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/value-not-equal.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/value-not-equal.js
new file mode 100644
index 0000000000..ff5cda2f9a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/value-not-equal.js
@@ -0,0 +1,62 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  3.Let v be ? ToBigInt64(value).
+    ...
+  14.If v is not equal to w, then
+    a.Perform LeaveCriticalSection(WL).
+    b. Return the String "not-equal".
+
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const value = "42n";
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report(Atomics.store(i64a, 0, ${value}));
+    $262.agent.report(Atomics.wait(i64a, 0, 0n));
+    $262.agent.leaving();
+  });
+`);
+
+// NB: We don't actually explicitly need to wait for the agent to start in this
+// test case, we only do it for consistency with other test cases which do
+// require the main agent to wait and yield control.
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  '42',
+  '$262.agent.getReport() returns "42"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'not-equal',
+  '$262.agent.getReport() returns "not-equal"'
+);
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-block-indexedposition-wake.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-block-indexedposition-wake.js
new file mode 100644
index 0000000000..cc71c5d8c3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-block-indexedposition-wake.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Get the correct WaiterList
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  ...
+  11. Let WL be GetWaiterList(block, indexedPosition).
+  ...
+
+
+  GetWaiterList( block, i )
+
+  ...
+  4. Return the WaiterList that is referenced by the pair (block, i).
+
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+var NUMAGENT = 2;
+var RUNNING = 4;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // Wait on index 0
+    $262.agent.report(Atomics.wait(i64a, 0, 0n, Infinity));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // Wait on index 2
+    $262.agent.report(Atomics.wait(i64a, 2, 0n, Infinity));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+
+// Wait until all agents started.
+$262.agent.waitUntil(i64a, RUNNING, BigInt(NUMAGENT));
+
+// Notify index 1, notifies nothing
+assert.sameValue(Atomics.notify(i64a, 1), 0, 'Atomics.notify(i64a, 1) returns 0');
+
+// Notify index 3, notifies nothing
+assert.sameValue(Atomics.notify(i64a, 3), 0, 'Atomics.notify(i64a, 3) returns 0');
+
+// Notify index 2, notifies 1
+var woken = 0;
+while ((woken = Atomics.notify(i64a, 2)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i64a, 2) returns 1');
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+// Notify index 0, notifies 1
+var woken = 0;
+while ((woken = Atomics.notify(i64a, 0)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i64a, 0) returns 1');
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-order-of-operations-is-fifo.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-order-of-operations-is-fifo.js
new file mode 100644
index 0000000000..9c7b45ee8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/waiterlist-order-of-operations-is-fifo.js
@@ -0,0 +1,95 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  New waiters should be applied to the end of the list and woken by order they entered the list (FIFO)
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  16.Perform AddWaiter(WL, W).
+    ...
+    3.Add W to the end of the list of waiters in WL.
+
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+var WAIT_INDEX = 0;
+var RUNNING = 1;
+var LOCK_INDEX = 2;
+var NUMAGENT = 3;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+for (var i = 0; i < NUMAGENT; i++) {
+  var agentNum = i;
+
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i64a = new BigInt64Array(sab);
+      Atomics.add(i64a, ${RUNNING}, 1n);
+
+      // Synchronize workers before reporting the initial report.
+      while (Atomics.compareExchange(i64a, ${LOCK_INDEX}, 0n, 1n) !== 0n) ;
+
+      // Report the agent number before waiting.
+      $262.agent.report(${agentNum});
+
+      // Wait until restarted by main thread.
+      var status = Atomics.wait(i64a, ${WAIT_INDEX}, 0n);
+
+      // Report wait status.
+      $262.agent.report(status);
+
+      // Report the agent number after waiting.
+      $262.agent.report(${agentNum});
+
+      $262.agent.leaving();
+    });
+  `);
+}
+
+$262.agent.safeBroadcast(i64a);
+
+// Wait until all agents started.
+$262.agent.waitUntil(i64a, RUNNING, BigInt(NUMAGENT));
+
+// Agents may be started in any order.
+const started = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  // Wait until an agent entered its critical section.
+  $262.agent.waitUntil(i64a, LOCK_INDEX, 1n);
+
+  // Record the agent number.
+  started.push($262.agent.getReport());
+
+  // The agent may have been interrupted between reporting its initial report
+  // and the `Atomics.wait` call. Try to yield control to ensure the agent
+  // actually started to wait.
+  $262.agent.tryYield();
+
+  // Now continue with the next agent.
+  Atomics.store(i64a, LOCK_INDEX, 0n);
+}
+
+// Agents must notify in the order they waited.
+for (var i = 0; i < NUMAGENT; i++) {
+  var woken = 0;
+  while ((woken = Atomics.notify(i64a, WAIT_INDEX, 1)) === 0) ;
+
+  assert.sameValue(woken, 1,
+                   'Atomics.notify(i64a, WAIT_INDEX, 1) returns 1, at index = ' + i);
+
+  assert.sameValue($262.agent.getReport(), 'ok',
+                   '$262.agent.getReport() returns "ok", at index = ' + i);
+
+  assert.sameValue($262.agent.getReport(), started[i],
+                   '$262.agent.getReport() returns the value of `started[' + i + ']`');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/bigint/was-woken-before-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/bigint/was-woken-before-timeout.js
new file mode 100644
index 0000000000..9b0658b492
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/bigint/was-woken-before-timeout.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait returns the right result when it was awoken before
+  a timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+includes: [atomicsHelper.js]
+features: [Atomics, BigInt, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.huge;
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i64a, 0, 0n, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i64a);
+$262.agent.waitUntil(i64a, RUNNING, 1n);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i64a, 0), 1, 'Atomics.notify(i64a, 0) returns 1');
+
+const lapse = $262.agent.getReport();
+
+assert(
+  lapse < TIMEOUT,
+  'The result of `(lapse < TIMEOUT)` is true'
+);
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/browser.js b/js/src/tests/test262/built-ins/Atomics/wait/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/cannot-suspend-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/cannot-suspend-throws.js
new file mode 100644
index 0000000000..a11c635cd1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/cannot-suspend-throws.js
@@ -0,0 +1,30 @@
+// |reftest| skip-if(xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- shell can block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Atomics.wait throws if agent cannot be suspended, CanBlock is false
+info: |
+  Assuming [[CanBlock]] is false for the main host.
+
+  Atomics.wait( typedArray, index, value, timeout )
+
+  ... (after args validation)
+  6. Let B be AgentCanSuspend().
+  7. If B is false, throw a TypeError exception.
+  ...
+features: [Atomics, SharedArrayBuffer, TypedArray]
+flags: [CanBlockIsFalse]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, 0, 0);
+}, '`Atomics.wait(i32a, 0, 0, 0)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/descriptor.js b/js/src/tests/test262/built-ins/Atomics/wait/descriptor.js
new file mode 100644
index 0000000000..36a7db4989
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: Testing descriptor property of Atomics.wait
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'wait', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout-agent.js
new file mode 100644
index 0000000000..8a099e7693
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout-agent.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf: function() {
+      return false;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      return false;
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const status1 = Atomics.wait(i32a, 0, 0, false);
+    const status2 = Atomics.wait(i32a, 0, 0, valueOf);
+    const status3 = Atomics.wait(i32a, 0, 0, toPrimitive);
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.report(status3);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout.js
new file mode 100644
index 0000000000..75675d64ac
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/false-for-timeout.js
@@ -0,0 +1,50 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf: function() {
+    return false;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    return false;
+  }
+};
+
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, false),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, false) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, valueOf),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, valueOf) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, toPrimitive),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, toPrimitive) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/good-views.js b/js/src/tests/test262/built-ins/Atomics/wait/good-views.js
new file mode 100644
index 0000000000..67e4da6314
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/good-views.js
@@ -0,0 +1,69 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test Atomics.wait on arrays that allow atomic operations,
+  in an Agent that is allowed to wait.
+includes: [atomicsHelper.js]
+features: [Atomics]
+---*/
+
+// Let's assume 'wait' is not allowed on the main thread,
+// even in the shell.
+
+$262.agent.start(`
+  var sab = new SharedArrayBuffer(1024);
+  var ab = new ArrayBuffer(16);
+
+  var good_indices = [ (view) => 0/-1, // -0
+                       (view) => '-0',
+                       (view) => view.length - 1,
+                       (view) => ({ valueOf: () => 0 }),
+                       (view) => ({ toString: () => '0', valueOf: false }) // non-callable valueOf triggers invocation of toString
+                     ];
+
+  var view = new Int32Array(sab, 32, 20);
+
+  view[0] = 0;
+  $262.agent.report("A " + Atomics.wait(view, 0, 0, 0))
+  $262.agent.report("B " + Atomics.wait(view, 0, 37, 0));
+
+  // In-bounds boundary cases for indexing
+  for ( let IdxGen of good_indices ) {
+      let Idx = IdxGen(view);
+      view.fill(0);
+      // Atomics.store() computes an index from Idx in the same way as other
+      // Atomics operations, not quite like view[Idx].
+      Atomics.store(view, Idx, 37);
+      $262.agent.report("C " + Atomics.wait(view, Idx, 0));
+  }
+
+  $262.agent.report("done");
+  $262.agent.leaving();
+`);
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'A timed-out',
+  '$262.agent.getReport() returns "A timed-out"'
+);
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'B not-equal',
+  '$262.agent.getReport() returns "B not-equal"'
+);
+
+var r;
+while ((r = $262.agent.getReport()) !== "done") {
+  assert.sameValue(
+    r,
+    'C not-equal',
+    '$262.agent.getReport() returns "C not-equal"'
+  );
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/length.js b/js/src/tests/test262/built-ins/Atomics/wait/length.js
new file mode 100644
index 0000000000..0cf786fa59
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/length.js
@@ -0,0 +1,35 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Atomics.wait.length is 4.
+info: |
+  Atomics.wait ( ia, index, expect, timeout )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.wait, 'length', {
+  value: 4,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/name.js b/js/src/tests/test262/built-ins/Atomics/wait/name.js
new file mode 100644
index 0000000000..b9a8813627
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Atomics.wait.name is "wait".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.wait, 'name', {
+  value: 'wait',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/nan-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/nan-for-timeout.js
new file mode 100644
index 0000000000..6992b4c664
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/nan-for-timeout.js
@@ -0,0 +1,46 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  NaN timeout arg should result in an infinite timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4.Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 0, NaN));  // NaN => +Infinity
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(i32a, 0) returns 1');
+assert.sameValue($262.agent.getReport(), "ok", '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/negative-index-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/negative-index-throws.js
new file mode 100644
index 0000000000..61d0b84067
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/negative-index-throws.js
@@ -0,0 +1,44 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a RangeError is index < 0
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+        ...
+        2.b If integerIndex < 0, throw a RangeError exception
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, -Infinity, poisoned, poisoned);
+}, '`Atomics.wait(i32a, -Infinity, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, -7.999, poisoned, poisoned);
+}, '`Atomics.wait(i32a, -7.999, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, -1, poisoned, poisoned);
+}, '`Atomics.wait(i32a, -1, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, -300, poisoned, poisoned);
+}, '`Atomics.wait(i32a, -300, poisoned, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout-agent.js
new file mode 100644
index 0000000000..f2441718df
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout-agent.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait times out with a negative timeout
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 0, -5)); // -5 => 0
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout.js
new file mode 100644
index 0000000000..22643b6e2a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/negative-timeout.js
@@ -0,0 +1,23 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait times out with a negative timeout
+features: [Atomics, SharedArrayBuffer, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, -1),
+  "timed-out",
+  'Atomics.wait(i32a, 0, 0, -1) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-no-operation.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-no-operation.js
new file mode 100644
index 0000000000..c17f9adb64
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-no-operation.js
@@ -0,0 +1,62 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait returns the right result when it timed out and that
+  the time to time out is reasonable.
+  info: |
+    17. Let awoken be Suspend(WL, W, t).
+    18. If awoken is true, then
+      a. Assert: W is not on the list of waiters in WL.
+    19. Else,
+      a.Perform RemoveWaiter(WL, W).
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+// NO OPERATION OCCURS HERE!
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-add.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-add.js
new file mode 100644
index 0000000000..f23eb83262
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-add.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Add operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.add(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-and.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-and.js
new file mode 100644
index 0000000000..17b94c3ed4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-and.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to And operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.and(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-compareExchange.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-compareExchange.js
new file mode 100644
index 0000000000..435a6aa751
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-compareExchange.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to compareExchange operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.compareExchange(i32a, 0, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-exchange.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-exchange.js
new file mode 100644
index 0000000000..de8af69711
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-exchange.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to exchange operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.exchange(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-or.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-or.js
new file mode 100644
index 0000000000..3282a35cfe
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-or.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Or operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.or(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-store.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-store.js
new file mode 100644
index 0000000000..94a9cf89cd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-store.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Store operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.store(i32a, 0, 0x111111);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-sub.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-sub.js
new file mode 100644
index 0000000000..27a96c6216
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-sub.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to Sub operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.sub(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-xor.js b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-xor.js
new file mode 100644
index 0000000000..a4ff96fb39
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/no-spurious-wakeup-on-xor.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Waiter does not spuriously notify on index which is subject to xor operation
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+Atomics.xor(i32a, 0, 1);
+
+const lapse = $262.agent.getReport();
+assert(
+  lapse >= TIMEOUT,
+  'The result of `(lapse >= TIMEOUT)` is true'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/non-int32-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/non-int32-typedarray-throws.js
new file mode 100644
index 0000000000..64fec573f5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/non-int32-typedarray-throws.js
@@ -0,0 +1,90 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if typedArray arg is not an Int32Array
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      5.If onlyInt32 is true, then
+        If typeName is not "Int32Array", throw a TypeError exception.
+features: [Atomics, Float32Array, Float64Array, Int8Array, TypedArray, Uint16Array, Uint8Array, Uint8ClampedArray]
+---*/
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  const view = new Float64Array(
+    new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Float64Array( new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Float32Array(
+    new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Float32Array( new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+if (typeof Float16Array !== 'undefined') {
+  assert.throws(TypeError, function() {
+    const view = new Float16Array(
+      new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2)
+    );
+    Atomics.wait(view, poisoned, poisoned, poisoned);
+  }, '`const view = new Float16Array( new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+}
+
+assert.throws(TypeError, function() {
+  const view = new Int16Array(
+    new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Int16Array( new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Int8Array(
+    new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Int8Array( new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint32Array(
+    new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint32Array( new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint16Array(
+    new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint16Array( new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint8Array(
+    new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint8Array( new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  const view = new Uint8ClampedArray(
+    new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT)
+  );
+  Atomics.wait(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint8ClampedArray( new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT) ); Atomics.wait(view, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/non-shared-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/non-shared-bufferdata-throws.js
new file mode 100644
index 0000000000..dcee5b7c34
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/non-shared-bufferdata-throws.js
@@ -0,0 +1,37 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if typedArray.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          4.If bufferData is a Data Block, return false.
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, 0, 0);
+}, '`Atomics.wait(i32a, 0, 0, 0)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(i32a, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/not-a-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/not-a-typedarray-throws.js
new file mode 100644
index 0000000000..484d1affec
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/not-a-typedarray-throws.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if the typedArray arg is not a TypedArray object
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+      3.If typedArray does not have a [[TypedArrayName]] internal slot, throw a TypeError exception.
+
+features: [Atomics]
+---*/
+
+var poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait({}, 0, 0, 0);
+}, '`Atomics.wait({}, 0, 0, 0)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait({}, poisoned, poisoned, poisoned);
+}, '`Atomics.wait({}, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/not-an-object-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/not-an-object-throws.js
new file mode 100644
index 0000000000..64ce6c2277
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/not-an-object-throws.js
@@ -0,0 +1,51 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if typedArray arg is not an Object
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  1.Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+    2. if Type(typedArray) is not Object, throw a TypeError exception
+features: [Atomics, Symbol]
+---*/
+
+var poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, function() {
+  Atomics.wait(null, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(null, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(undefined, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(undefined, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(true, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(true, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(false, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(false, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait('***string***', poisoned, poisoned, poisoned);
+}, '`Atomics.wait(\'***string***\', poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(Symbol('***symbol***'), poisoned, poisoned, poisoned);
+}, '`Atomics.wait(Symbol(\'***symbol***\'), poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/null-bufferdata-throws.js
new file mode 100644
index 0000000000..0b8ab82185
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/null-bufferdata-throws.js
@@ -0,0 +1,46 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  A null value for bufferData (detached) throws a TypeError
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  Let buffer be ? ValidateIntegerTypedArray(typedArray, true).
+  ...
+
+    Let buffer be ? ValidateTypedArray(typedArray).
+    ...
+
+      If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
+      ...
+
+        If arrayBuffer.[[ArrayBufferData]] is null, return true.
+
+includes: [detachArrayBuffer.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i32a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, poisoned, poisoned, poisoned);
+}, '`Atomics.wait(i32a, poisoned, poisoned, poisoned)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout-agent.js
new file mode 100644
index 0000000000..2cc92711cc
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout-agent.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf: function() {
+      return null;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      return null;
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const status1 = Atomics.wait(i32a, 0, 0, null);
+    const status2 = Atomics.wait(i32a, 0, 0, valueOf);
+    const status3 = Atomics.wait(i32a, 0, 0, toPrimitive);
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.report(status3);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout.js
new file mode 100644
index 0000000000..39b7979469
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/null-for-timeout.js
@@ -0,0 +1,52 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf: function() {
+    return null;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    return null;
+  }
+};
+
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, null),
+  "timed-out",
+  'Atomics.wait(i32a, 0, 0, null) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, valueOf),
+  "timed-out",
+  'Atomics.wait(i32a, 0, 0, valueOf) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, toPrimitive),
+  "timed-out",
+  'Atomics.wait(i32a, 0, 0, toPrimitive) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout-agent.js
new file mode 100644
index 0000000000..dd293ca2a2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout-agent.js
@@ -0,0 +1,84 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf: function() {
+      return 0;
+    }
+  };
+
+  const toString = {
+    toString: function() {
+      return "0";
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      return 0;
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const status1 = Atomics.wait(i32a, 0, 0, valueOf);
+    const status2 = Atomics.wait(i32a, 0, 0, toString);
+    const status3 = Atomics.wait(i32a, 0, 0, toPrimitive);
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.report(status3);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout.js
new file mode 100644
index 0000000000..2d3600397f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/object-for-timeout.js
@@ -0,0 +1,61 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf: function() {
+    return 0;
+  }
+};
+
+const toString = {
+  toString: function() {
+    return "0";
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    return 0;
+  }
+};
+
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, valueOf),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, valueOf) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, toString),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, toString) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, toPrimitive),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, toPrimitive) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/out-of-range-index-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/out-of-range-index-throws.js
new file mode 100644
index 0000000000..d2d3fdea27
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/out-of-range-index-throws.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a RangeError if value of index arg is out of range
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+    2.Let accessIndex be ? ToIndex(requestIndex).
+    ...
+    5. If accessIndex ≥ length, throw a RangeError exception.
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, Infinity, poisoned, poisoned);
+}, '`Atomics.wait(i32a, Infinity, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, -1, poisoned, poisoned);
+}, '`Atomics.wait(i32a, -1, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, 4, poisoned, poisoned);
+}, '`Atomics.wait(i32a, 4, poisoned, poisoned)` throws RangeError');
+assert.throws(RangeError, function() {
+  Atomics.wait(i32a, 200, poisoned, poisoned);
+}, '`Atomics.wait(i32a, 200, poisoned, poisoned)` throws RangeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..8735e13f56
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws-agent.js
@@ -0,0 +1,82 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf: function() {
+      throw new Error("should not evaluate this code");
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      throw new Error("passing a poisoned object using @@ToPrimitive");
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.wait(i32a, 0, 0, poisonedValueOf);
+    } catch (error) {
+      status1 = "poisonedValueOf";
+    }
+    try {
+      Atomics.wait(i32a, 0, 0, poisonedToPrimitive);
+    } catch (error) {
+      status2 = "poisonedToPrimitive";
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'poisonedValueOf',
+  '$262.agent.getReport() returns "poisonedValueOf"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'poisonedToPrimitive',
+  '$262.agent.getReport() returns "poisonedToPrimitive"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws.js
new file mode 100644
index 0000000000..2d41dcb4d6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/poisoned-object-for-timeout-throws.js
@@ -0,0 +1,46 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, 0, poisonedValueOf);
+}, '`Atomics.wait(i32a, 0, 0, poisonedValueOf)` throws Test262Error');
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, 0, poisonedToPrimitive);
+}, '`Atomics.wait(i32a, 0, 0, poisonedToPrimitive)` throws Test262Error');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/shell.js b/js/src/tests/test262/built-ins/Atomics/wait/shell.js
new file mode 100644
index 0000000000..c55dbb8399
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/shell.js
@@ -0,0 +1,344 @@
+// GENERATED, DO NOT EDIT
+// file: atomicsHelper.js
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: >
+    Collection of functions used to interact with Atomics.* operations across agent boundaries.
+defines:
+  - $262.agent.getReportAsync
+  - $262.agent.getReport
+  - $262.agent.safeBroadcastAsync
+  - $262.agent.safeBroadcast
+  - $262.agent.setTimeout
+  - $262.agent.tryYield
+  - $262.agent.trySleep
+---*/
+
+/**
+ * @return {String} A report sent from an agent.
+ */
+{
+  // This is only necessary because the original
+  // $262.agent.getReport API was insufficient.
+  //
+  // All runtimes currently have their own
+  // $262.agent.getReport which is wrong, so we
+  // will pave over it with a corrected version.
+  //
+  // Binding $262.agent is necessary to prevent
+  // breaking SpiderMonkey's $262.agent.getReport
+  let getReport = $262.agent.getReport.bind($262.agent);
+
+  $262.agent.getReport = function() {
+    var r;
+    while ((r = getReport()) == null) {
+      $262.agent.sleep(1);
+    }
+    return r;
+  };
+
+  if (this.setTimeout === undefined) {
+    (function(that) {
+      that.setTimeout = function(callback, delay) {
+        let p = Promise.resolve();
+        let start = Date.now();
+        let end = start + delay;
+        function check() {
+          if ((end - Date.now()) > 0) {
+            p.then(check);
+          }
+          else {
+            callback();
+          }
+        }
+        p.then(check);
+      }
+    })(this);
+  }
+
+  $262.agent.setTimeout = setTimeout;
+
+  $262.agent.getReportAsync = function() {
+    return new Promise(function(resolve) {
+      (function loop() {
+        let result = getReport();
+        if (!result) {
+          setTimeout(loop, 1000);
+        } else {
+          resolve(result);
+        }
+      })();
+    });
+  };
+}
+
+/**
+ *
+ * Share a given Int32Array or BigInt64Array to all running agents. Ensure that the
+ * provided TypedArray is a "shared typed array".
+ *
+ * NOTE: Migrating all tests to this API is necessary to prevent tests from hanging
+ * indefinitely when a SAB is sent to a worker but the code in the worker attempts to
+ * create a non-sharable TypedArray (something that is not Int32Array or BigInt64Array).
+ * When that scenario occurs, an exception is thrown and the agent worker can no
+ * longer communicate with any other threads that control the SAB. If the main
+ * thread happens to be spinning in the $262.agent.waitUntil() while loop, it will never
+ * meet its termination condition and the test will hang indefinitely.
+ *
+ * Because we've defined $262.agent.broadcast(SAB) in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md, there are host implementations
+ * that assume compatibility, which must be maintained.
+ *
+ *
+ * $262.agent.safeBroadcast(TA) should not be included in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md
+ *
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ */
+$262.agent.safeBroadcast = function(typedArray) {
+  let Constructor = Object.getPrototypeOf(typedArray).constructor;
+  let temp = new Constructor(
+    new SharedArrayBuffer(Constructor.BYTES_PER_ELEMENT)
+  );
+  try {
+    // This will never actually wait, but that's fine because we only
+    // want to ensure that this typedArray CAN be waited on and is shareable.
+    Atomics.wait(temp, 0, Constructor === Int32Array ? 1 : BigInt(1));
+  } catch (error) {
+    throw new Test262Error(`${Constructor.name} cannot be used as a shared typed array. (${error})`);
+  }
+
+  $262.agent.broadcast(typedArray.buffer);
+};
+
+$262.agent.safeBroadcastAsync = async function(ta, index, expected) {
+  await $262.agent.broadcast(ta.buffer);
+  await $262.agent.waitUntil(ta, index, expected);
+  await $262.agent.tryYield();
+  return await Atomics.load(ta, index);
+};
+
+
+/**
+ * With a given Int32Array or BigInt64Array, wait until the expected number of agents have
+ * reported themselves by calling:
+ *
+ *    Atomics.add(typedArray, index, 1);
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ * @param {number} index    The index of which all agents will report.
+ * @param {number} expected The number of agents that are expected to report as active.
+ */
+$262.agent.waitUntil = function(typedArray, index, expected) {
+
+  var agents = 0;
+  while ((agents = Atomics.load(typedArray, index)) !== expected) {
+    /* nothing */
+  }
+  assert.sameValue(agents, expected, "Reporting number of 'agents' equals the value of 'expected'");
+};
+
+/**
+ * Timeout values used throughout the Atomics tests. All timeouts are specified in milliseconds.
+ *
+ * @property {number} yield Used for `$262.agent.tryYield`. Must not be used in other functions.
+ * @property {number} small Used when agents will always timeout and `Atomics.wake` is not part
+ *                          of the test semantics. Must be larger than `$262.agent.timeouts.yield`.
+ * @property {number} long  Used when some agents may timeout and `Atomics.wake` is called on some
+ *                          agents. The agents are required to wait and this needs to be observable
+ *                          by the main thread.
+ * @property {number} huge  Used when `Atomics.wake` is called on all waiting agents. The waiting
+ *                          must not timeout. The agents are required to wait and this needs to be
+ *                          observable by the main thread. All waiting agents must be woken by the
+ *                          main thread.
+ *
+ * Usage for `$262.agent.timeouts.small`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const TIMEOUT = $262.agent.timeouts.small;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agent was started and then try to yield control to increase
+ *   // the likelihood the agent has called `Atomics.wait` and is now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // The agent is expected to time out.
+ *   assert.sameValue($262.agent.getReport(), "timed-out");
+ *
+ *
+ * Usage for `$262.agent.timeouts.long`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.long;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake exactly one agent.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX, 1), 1);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until exactly one agent was woken.
+ *   // var woken = 0;
+ *   // while ((woken = Atomics.wake(i32a, WAIT_INDEX, 1)) !== 0) ;
+ *   // assert.sameValue(woken, 1);
+ *
+ *   // One agent was woken and the other one timed out.
+ *   const reports = [$262.agent.getReport(), $262.agent.getReport()];
+ *   assert(reports.includes("ok"));
+ *   assert(reports.includes("timed-out"));
+ *
+ *
+ * Usage for `$262.agent.timeouts.huge`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.huge;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake all agents.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX), NUMAGENT);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until all agents were woken.
+ *   // for (var wokenCount = 0; wokenCount < NUMAGENT; ) {
+ *   //   var woken = 0;
+ *   //   while ((woken = Atomics.wake(i32a, WAIT_INDEX)) !== 0) ;
+ *   //   // Maybe perform an action on the woken agents here.
+ *   //   wokenCount += woken;
+ *   // }
+ *
+ *   // All agents were woken and none timeout.
+ *   for (var i = 0; i < NUMAGENT; i++) {
+ *     assert($262.agent.getReport(), "ok");
+ *   }
+ */
+$262.agent.timeouts = {
+  yield: 100,
+  small: 200,
+  long: 1000,
+  huge: 10000,
+};
+
+/**
+ * Try to yield control to the agent threads.
+ *
+ * Usage:
+ *   const VALUE = 0;
+ *   const RUNNING = 1;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       Atomics.store(i32a, ${VALUE}, 1);
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until agent was started and then try to yield control.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // Note: This result is not guaranteed, but should hold in practice most of the time.
+ *   assert.sameValue(Atomics.load(i32a, VALUE), 1);
+ *
+ * The default implementation simply waits for `$262.agent.timeouts.yield` milliseconds.
+ */
+$262.agent.tryYield = function() {
+  $262.agent.sleep($262.agent.timeouts.yield);
+};
+
+/**
+ * Try to sleep the current agent for the given amount of milliseconds. It is acceptable,
+ * but not encouraged, to ignore this sleep request and directly continue execution.
+ *
+ * The default implementation calls `$262.agent.sleep(ms)`.
+ *
+ * @param {number} ms Time to sleep in milliseconds.
+ */
+$262.agent.trySleep = function(ms) {
+  $262.agent.sleep(ms);
+};
+
+// file: detachArrayBuffer.js
+// Copyright (C) 2016 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A function used in the process of asserting correctness of TypedArray objects.
+
+    $262.detachArrayBuffer is defined by a host.
+defines: [$DETACHBUFFER]
+---*/
+
+function $DETACHBUFFER(buffer) {
+  if (!$262 || typeof $262.detachArrayBuffer !== "function") {
+    throw new Test262Error("No method available to detach an ArrayBuffer");
+  }
+  $262.detachArrayBuffer(buffer);
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws-agent.js
new file mode 100644
index 0000000000..3fb393df44
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws-agent.js
@@ -0,0 +1,95 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf: function() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.wait(i32a, Symbol("1"), poisonedValueOf, poisonedValueOf);
+    } catch (error) {
+      status1 = 'Symbol("1")';
+    }
+    try {
+      Atomics.wait(i32a, Symbol("2"), poisonedToPrimitive, poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'Symbol("2")';
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("1")',
+  '$262.agent.getReport() returns "Symbol("1")"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("2")',
+  '$262.agent.getReport() returns "Symbol("2")"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws.js
new file mode 100644
index 0000000000..332588e972
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-index-throws.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, poisonedValueOf, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.wait(i32a, poisonedValueOf, poisonedValueOf, poisonedValueOf)` throws Test262Error');
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.wait(i32a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive)` throws Test262Error');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, Symbol('foo'), poisonedValueOf, poisonedValueOf);
+}, '`Atomics.wait(i32a, Symbol(\'foo\'), poisonedValueOf, poisonedValueOf)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, Symbol('foo'), poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.wait(i32a, Symbol(\'foo\'), poisonedToPrimitive, poisonedToPrimitive)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..4518b89ce9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws-agent.js
@@ -0,0 +1,70 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.wait(i32a, 0, 0, Symbol("1"));
+    } catch (error) {
+      status1 = 'Symbol("1")';
+    }
+    try {
+      Atomics.wait(i32a, 0, 0, Symbol("2"));
+    } catch (error) {
+      status2 = 'Symbol("2")';
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("1")',
+  '$262.agent.getReport() returns "Symbol("1")"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("2")',
+  '$262.agent.getReport() returns "Symbol("2")"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws.js
new file mode 100644
index 0000000000..76d6874f28
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-timeout-throws.js
@@ -0,0 +1,50 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(1024);
+var i32a = new Int32Array(buffer);
+
+var poisonedValueOf = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+var poisonedToPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    throw new Test262Error('passing a poisoned object using @@ToPrimitive');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, 0, poisonedValueOf);
+}, '`Atomics.wait(i32a, 0, 0, poisonedValueOf)` throws Test262Error');
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, 0, poisonedToPrimitive);
+}, '`Atomics.wait(i32a, 0, 0, poisonedToPrimitive)` throws Test262Error');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, 0, Symbol("foo"));
+}, '`Atomics.wait(i32a, 0, 0, Symbol("foo"))` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, 0, Symbol("foo"));
+}, '`Atomics.wait(i32a, 0, 0, Symbol("foo"))` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws-agent.js
new file mode 100644
index 0000000000..3647060de9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws-agent.js
@@ -0,0 +1,86 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  3. Let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf: function() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.wait(i32a, 0, Symbol("1"), poisonedValueOf);
+    } catch (error) {
+      status1 = 'Symbol("1")';
+    }
+    try {
+      Atomics.wait(i32a, 0, Symbol("2"), poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'Symbol("2")';
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("1")',
+  '$262.agent.getReport() returns "Symbol("1")"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'Symbol("2")',
+  '$262.agent.getReport() returns "Symbol("2")"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws.js b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws.js
new file mode 100644
index 0000000000..3a4e3a8cbf
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/symbol-for-value-throws.js
@@ -0,0 +1,55 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  3. Let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf: function() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.wait(i32a, 0, poisonedValueOf, poisonedValueOf)` throws Test262Error');
+
+assert.throws(Test262Error, function() {
+  Atomics.wait(i32a, 0, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.wait(i32a, 0, poisonedToPrimitive, poisonedToPrimitive)` throws Test262Error');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, Symbol("foo"), poisonedValueOf);
+}, '`Atomics.wait(i32a, 0, Symbol("foo"), poisonedValueOf)` throws TypeError');
+
+assert.throws(TypeError, function() {
+  Atomics.wait(i32a, 0, Symbol("foo"), poisonedToPrimitive);
+}, '`Atomics.wait(i32a, 0, Symbol("foo"), poisonedToPrimitive)` throws TypeError');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout-agent.js
new file mode 100644
index 0000000000..1dbed93889
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout-agent.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  True timeout arg should result in an +0 timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf: function() {
+      return true;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      return true;
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const status1 = Atomics.wait(i32a, 0, 0, true);
+    const status2 = Atomics.wait(i32a, 0, 0, valueOf);
+    const status3 = Atomics.wait(i32a, 0, 0, toPrimitive);
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.report(status3);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'timed-out',
+  '$262.agent.getReport() returns "timed-out"'
+);
+
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout.js
new file mode 100644
index 0000000000..0bc8bdfb48
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/true-for-timeout.js
@@ -0,0 +1,52 @@
+// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- browser cannot block main thread, Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+features: [Atomics, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray]
+flags: [CanBlockIsTrue]
+---*/
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf: function() {
+    return true;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]: function() {
+    return true;
+  }
+};
+
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, true),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, true) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, valueOf),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, valueOf) returns "timed-out"'
+);
+assert.sameValue(
+  Atomics.wait(i32a, 0, 0, toPrimitive),
+  'timed-out',
+  'Atomics.wait(i32a, 0, 0, toPrimitive) returns "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/undefined-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/undefined-for-timeout.js
new file mode 100644
index 0000000000..c95d892804
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/undefined-for-timeout.js
@@ -0,0 +1,73 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Undefined timeout arg should result in an infinite timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  4.Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const WAIT_INDEX = 0; // Index all agents are waiting on
+const RUNNING = 1;
+const NUMAGENT = 2;   // Total number of agents started
+const NOTIFYCOUNT = 2;  // Total number of agents to notify up
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined => NaN => +Infinity
+    $262.agent.report("A " + Atomics.wait(i32a, 0, 0, undefined));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined timeout arg => NaN => +Infinity
+    $262.agent.report("B " + Atomics.wait(i32a, 0, 0));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT),
+  NOTIFYCOUNT,
+  'Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT) returns the value of `NOTIFYCOUNT` (2)'
+);
+
+const reports = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  reports.push($262.agent.getReport());
+}
+reports.sort();
+
+assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/undefined-index-defaults-to-zero.js b/js/src/tests/test262/built-ins/Atomics/wait/undefined-index-defaults-to-zero.js
new file mode 100644
index 0000000000..ce3546b861
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/undefined-index-defaults-to-zero.js
@@ -0,0 +1,53 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  An undefined index arg should translate to 0
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.long;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, undefined, 0, ${TIMEOUT})); // undefined index => 0
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(i32a, 0) returns 1'); // notify at index 0
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0'); // notify again at index 0, and 0 agents should be woken
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..26586d313e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.11 Atomics.wait ( typedArray, index, value, timeout )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+var badArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (var badArrayType of badArrayTypes) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.wait(typedArray, index, 0, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-timeout-coercion.js b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-timeout-coercion.js
new file mode 100644
index 0000000000..58328bc348
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-timeout-coercion.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  TypedArray type is validated before `timeout` argument is coerced.
+info: |
+  24.4.11 Atomics.wait ( typedArray, index, value, timeout )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var timeout = {
+  valueOf() {
+    throw new Test262Error("timeout coerced");
+  }
+};
+
+var badArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (var badArrayType of badArrayTypes) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.wait(typedArray, 0, 0, timeout);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..b597ebf9f2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,42 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.11 Atomics.wait ( typedArray, index, value, timeout )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+var badArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (var badArrayType of badArrayTypes) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.wait(typedArray, 0, value, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/value-not-equal.js b/js/src/tests/test262/built-ins/Atomics/wait/value-not-equal.js
new file mode 100644
index 0000000000..269b6923c6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/value-not-equal.js
@@ -0,0 +1,62 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  3.Let v be ? ToInt32(value).
+    ...
+  14.If v is not equal to w, then
+    a.Perform LeaveCriticalSection(WL).
+    b. Return the String "not-equal".
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+
+var value = 42;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.store(i32a, 0, ${value}));
+    $262.agent.report(Atomics.wait(i32a, 0, 0));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+// NB: We don't actually explicitly need to wait for the agent to start in this
+// test case, we only do it for consistency with other test cases which do
+// require the main agent to wait and yield control.
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  value.toString(),
+  '$262.agent.getReport() returns value.toString()'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'not-equal',
+  '$262.agent.getReport() returns "not-equal"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/wait-index-value-not-equal.js b/js/src/tests/test262/built-ins/Atomics/wait/wait-index-value-not-equal.js
new file mode 100644
index 0000000000..f68c2eecd0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/wait-index-value-not-equal.js
@@ -0,0 +1,60 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Returns "not-equal" when value of index is not equal
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  14.If v is not equal to w, then
+    a.Perform LeaveCriticalSection(WL).
+    b. Return the String "not-equal".
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.wait(i32a, 0, 44, ${TIMEOUT}));
+    $262.agent.report(Atomics.wait(i32a, 0, 251.4, ${TIMEOUT}));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+// NB: We don't actually explicitly need to wait for the agent to start in this
+// test case, we only do it for consistency with other test cases which do
+// require the main agent to wait and yield control.
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(
+  $262.agent.getReport(),
+  'not-equal',
+  '$262.agent.getReport() returns "not-equal"'
+);
+assert.sameValue(
+  $262.agent.getReport(),
+  'not-equal',
+  '$262.agent.getReport() returns "not-equal"'
+);
+assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-block-indexedposition-wake.js b/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-block-indexedposition-wake.js
new file mode 100644
index 0000000000..d321a45e33
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-block-indexedposition-wake.js
@@ -0,0 +1,78 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  Get the correct WaiterList
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  ...
+  11. Let WL be GetWaiterList(block, indexedPosition).
+  ...
+
+
+  GetWaiterList( block, i )
+
+  ...
+  4. Return the WaiterList that is referenced by the pair (block, i).
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+var NUMAGENT = 2;
+var RUNNING = 4;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // Wait on index 0
+    $262.agent.report(Atomics.wait(i32a, 0, 0, Infinity));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // Wait on index 2
+    $262.agent.report(Atomics.wait(i32a, 2, 0, Infinity));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait until all agents started.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Notify index 1, notifies nothing
+assert.sameValue(Atomics.notify(i32a, 1), 0, 'Atomics.notify(i32a, 1) returns 0');
+
+// Notify index 3, notifies nothing
+assert.sameValue(Atomics.notify(i32a, 3), 0, 'Atomics.notify(i32a, 3) returns 0');
+
+// Notify index 2, notifies 1
+var woken = 0;
+while ((woken = Atomics.notify(i32a, 2)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i32a, 2) returns 1');
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+// Notify index 0, notifies 1
+var woken = 0;
+while ((woken = Atomics.notify(i32a, 0)) === 0) ;
+assert.sameValue(woken, 1, 'Atomics.notify(i32a, 0) returns 1');
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-order-of-operations-is-fifo.js b/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-order-of-operations-is-fifo.js
new file mode 100644
index 0000000000..ef650f7e5a
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/waiterlist-order-of-operations-is-fifo.js
@@ -0,0 +1,96 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.wait
+description: >
+  New waiters should be applied to the end of the list and woken by order they entered the list (FIFO)
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  16.Perform AddWaiter(WL, W).
+    ...
+    3.Add W to the end of the list of waiters in WL.
+
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+var NUMAGENT = 3;
+
+var WAIT_INDEX = 0;
+var RUNNING = 1;
+var LOCK_INDEX = 2;
+
+for (var i = 0; i < NUMAGENT; i++) {
+  var agentNum = i;
+
+  $262.agent.start(`
+    $262.agent.receiveBroadcast(function(sab) {
+      const i32a = new Int32Array(sab);
+      Atomics.add(i32a, ${RUNNING}, 1);
+
+      // Synchronize workers before reporting the initial report.
+      while (Atomics.compareExchange(i32a, ${LOCK_INDEX}, 0, 1) !== 0) ;
+
+      // Report the agent number before waiting.
+      $262.agent.report(${agentNum});
+
+      // Wait until restarted by main thread.
+      var status = Atomics.wait(i32a, ${WAIT_INDEX}, 0);
+
+      // Report wait status.
+      $262.agent.report(status);
+
+      // Report the agent number after waiting.
+      $262.agent.report(${agentNum});
+
+      $262.agent.leaving();
+    });
+  `);
+}
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+
+// Wait until all agents started.
+$262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+
+// Agents may be started in any order.
+const started = [];
+for (var i = 0; i < NUMAGENT; i++) {
+  // Wait until an agent entered its critical section.
+  $262.agent.waitUntil(i32a, LOCK_INDEX, 1);
+
+  // Record the agent number.
+  started.push($262.agent.getReport());
+
+  // The agent may have been interrupted between reporting its initial report
+  // and the `Atomics.wait` call. Try to yield control to ensure the agent
+  // actually started to wait.
+  $262.agent.tryYield();
+
+  // Now continue with the next agent.
+  Atomics.store(i32a, LOCK_INDEX, 0);
+}
+
+// Agents must notify in the order they waited.
+for (var i = 0; i < NUMAGENT; i++) {
+  var woken = 0;
+  while ((woken = Atomics.notify(i32a, WAIT_INDEX, 1)) === 0) ;
+
+  assert.sameValue(woken, 1,
+                   'Atomics.notify(i32a, WAIT_INDEX, 1) returns 1, at index = ' + i);
+
+  assert.sameValue($262.agent.getReport(), 'ok',
+                   '$262.agent.getReport() returns "ok", at index = ' + i);
+
+  assert.sameValue($262.agent.getReport(), started[i],
+                   '$262.agent.getReport() returns the value of `started[' + i + ']`');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/wait/was-woken-before-timeout.js b/js/src/tests/test262/built-ins/Atomics/wait/was-woken-before-timeout.js
new file mode 100644
index 0000000000..be10304bb9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/wait/was-woken-before-timeout.js
@@ -0,0 +1,64 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Amal Hussein. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.wait
+description: >
+  Test that Atomics.wait returns the right result when it was awoken before
+  a timeout
+info: |
+  Atomics.wait( typedArray, index, value, timeout )
+
+  2.Let i be ? ValidateAtomicAccess(typedArray, index).
+    ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+includes: [atomicsHelper.js]
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.huge;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = Atomics.wait(i32a, 0, 0, ${TIMEOUT});
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcast(i32a);
+$262.agent.waitUntil(i32a, RUNNING, 1);
+
+// Try to yield control to ensure the agent actually started to wait.
+$262.agent.tryYield();
+
+assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(i32a, 0) returns 1');
+
+const lapse = $262.agent.getReport();
+
+assert(
+  lapse < TIMEOUT,
+  'The result of `(lapse < TIMEOUT)` is true'
+);
+assert.sameValue($262.agent.getReport(), 'ok', '$262.agent.getReport() returns "ok"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bad-range.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bad-range.js
new file mode 100644
index 0000000000..251bb9384f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bad-range.js
@@ -0,0 +1,36 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test range checking of Atomics.waitAsync on arrays that allow atomic operations
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+  ...
+
+includes: [testAtomics.js]
+features: [Atomics.waitAsync, Atomics, SharedArrayBuffer, ArrayBuffer, DataView, Symbol, TypedArray]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.waitAsync(i32a, IdxGen(i32a), 0, 0);
+  }, '`Atomics.waitAsync(i32a, IdxGen(i32a), 0, 0)` throws a RangeError exception');
+});
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/bad-range.js
new file mode 100644
index 0000000000..a2214e5b2b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/bad-range.js
@@ -0,0 +1,31 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test range checking of Atomics.waitAsync on arrays that allow atomic operations
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+  ...
+
+includes: [testAtomics.js]
+features: [Atomics.waitAsync, Atomics, SharedArrayBuffer, ArrayBuffer, DataView, Symbol, TypedArray, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 8));
+
+testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+  assert.throws(RangeError, function() {
+    Atomics.waitAsync(i64a, IdxGen(i64a), 0n, 0);
+  }, '`Atomics.waitAsync(i64a, IdxGen(i64a), 0n, 0)` throws a RangeError exception');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout-agent.js
new file mode 100644
index 0000000000..37bb338b35
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout-agent.js
@@ -0,0 +1,96 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return false;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return false;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, false).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, false).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout.js
new file mode 100644
index 0000000000..78e5cb927c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/false-for-timeout.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return false;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return false;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, false).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, false).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, valueOf).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value is "timed-out"'
+);
+
+Promise.all([
+  Atomics.waitAsync(i64a, 0, 0n, false).value,
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value
+]).then(outcomes => {
+  assert.sameValue(outcomes[0], 'timed-out', 'The value of outcomes[0] is "timed-out"');
+  assert.sameValue(outcomes[1], 'timed-out', 'The value of outcomes[1] is "timed-out"');
+  assert.sameValue(outcomes[2], 'timed-out', 'The value of outcomes[2] is "timed-out"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/good-views.js
new file mode 100644
index 0000000000..8a084276ad
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/good-views.js
@@ -0,0 +1,71 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test Atomics.waitAsync on arrays that allow atomic operations
+flags: [async]
+includes: [atomicsHelper.js, asyncHelpers.js]
+features: [Atomics.waitAsync, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+$262.agent.start(`
+  (async () => {
+    var sab = new SharedArrayBuffer(2048);
+    var good_indices = [ (view) => 0/-1, // -0
+                         (view) => '-0',
+                         (view) => view.length - 1,
+                         (view) => ({ valueOf: () => 0 }),
+                         (view) => ({ toString: () => '0', valueOf: false }) // non-callable valueOf triggers invocation of toString
+                       ];
+
+    var view = new BigInt64Array(sab, 32, 20);
+
+    view[0] = 0n;
+    $262.agent.report("A " + (await Atomics.waitAsync(view, 0, 0n, 0).value))
+    $262.agent.report("B " + (await Atomics.waitAsync(view, 0, 37n, 0).value));
+
+    const results = [];
+    // In-bounds boundary cases for indexing
+    for ( let IdxGen of good_indices ) {
+        let Idx = IdxGen(view);
+        view.fill(0n);
+        // Atomics.store() computes an index from Idx in the same way as other
+        // Atomics operations, not quite like view[Idx].
+        Atomics.store(view, Idx, 37n);
+        results.push(await Atomics.waitAsync(view, Idx, 0n).value);
+    }
+    $262.agent.report("C " + results.join(","));
+
+    $262.agent.leaving();
+  })();
+`);
+
+
+asyncTest(async () => {
+  const outcomes = [];
+
+  for (let i = 0; i < 3; i++) {
+    outcomes.push(await $262.agent.getReportAsync());
+  }
+
+  assert.sameValue(
+    outcomes[0],
+    'A timed-out',
+    'The value of outcomes[0] is "A timed-out"'
+  );
+
+  assert.sameValue(
+    outcomes[1],
+    'B not-equal',
+    'The value of outcomes[1] is "B not-equal"'
+  );
+  assert.sameValue(
+    outcomes[2],
+    'C not-equal,not-equal,not-equal,not-equal,not-equal',
+    'The value of outcomes[2] is "C not-equal,not-equal,not-equal,not-equal,not-equal"'
+  );
+});
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/nan-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/nan-for-timeout-agent.js
new file mode 100644
index 0000000000..70f79c11e0
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/nan-for-timeout-agent.js
@@ -0,0 +1,50 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  NaN timeout arg should result in an infinite timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, NaN).value);  // NaN => +Infinity
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    1,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 1'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-index-throws.js
new file mode 100644
index 0000000000..0618a9aa71
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-index-throws.js
@@ -0,0 +1,46 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a RangeError is index < 0
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, -Infinity, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, -Infinity, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, -7.999, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, -7.999, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, -1, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, -1, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, -300, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, -300, poisoned, poisoned)` throws a RangeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout-agent.js
new file mode 100644
index 0000000000..9ef681c34b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout-agent.js
@@ -0,0 +1,49 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, -5).value); // -5 => 0
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout.js
new file mode 100644
index 0000000000..2f0f64af62
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/negative-timeout.js
@@ -0,0 +1,25 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, destructuring-binding, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+Promise.all([Atomics.waitAsync(i64a, 0, 0n, -1).value]).then(([outcome]) => {
+  assert.sameValue(outcome, 'timed-out', 'The value of `outcome` is "timed-out"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-no-operation.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-no-operation.js
new file mode 100644
index 0000000000..a87317a889
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-no-operation.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync returns the right result when it timed out and that
+  the time to time out is reasonable.
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-add.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-add.js
new file mode 100644
index 0000000000..e15da5a1e2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-add.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Add operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.add(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-and.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-and.js
new file mode 100644
index 0000000000..02ed9ef726
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-and.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to And operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.and(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-compareExchange.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-compareExchange.js
new file mode 100644
index 0000000000..36308c49b6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-compareExchange.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to compareExchange operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.compareExchange(i64a, 0, 0n, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-exchange.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-exchange.js
new file mode 100644
index 0000000000..93e73140bb
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-exchange.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to exchange operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.exchange(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-or.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-or.js
new file mode 100644
index 0000000000..321f100417
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-or.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Or operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.or(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-store.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-store.js
new file mode 100644
index 0000000000..74b2a930b2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-store.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Store operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.store(i64a, 0, 0b1010n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-sub.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-sub.js
new file mode 100644
index 0000000000..9359795e8b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-sub.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Sub operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.sub(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-xor.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-xor.js
new file mode 100644
index 0000000000..dfc8d00b07
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/no-spurious-wakeup-on-xor.js
@@ -0,0 +1,61 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to xor operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+  Atomics.xor(i64a, 0, 1n);
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse >= TIMEOUT, 'The result of evaluating `(lapse >= TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'timed-out', 'The value of `result` is "timed-out"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-bigint64-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-bigint64-typedarray-throws.js
new file mode 100644
index 0000000000..a4e3dd79f7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-bigint64-typedarray-throws.js
@@ -0,0 +1,38 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray arg is not an BigInt64Array
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+
+features: [Atomics.waitAsync, Float32Array, Float64Array, Int8Array, TypedArray, Uint16Array, Uint8Array, Uint8ClampedArray, arrow-function, SharedArrayBuffer, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  const view = new BigUint64Array(new SharedArrayBuffer(BigUint64Array.BYTES_PER_ELEMENT * 8));
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new BigUint64Array(new SharedArrayBuffer(BigUint64Array.BYTES_PER_ELEMENT * 8)); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-shared-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-shared-bufferdata-throws.js
new file mode 100644
index 0000000000..def8fe86ea
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/non-shared-bufferdata-throws.js
@@ -0,0 +1,41 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  5. If waitable is true, then
+    a. If typeName is not "BigInt64Array" or "BigInt64Array", throw a TypeError exception.
+
+features: [Atomics.waitAsync, ArrayBuffer, Atomics, TypedArray, BigInt, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(i64a, 0, 0n, 0);
+}, '`Atomics.waitAsync(i64a, 0, 0n, 0)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(i64a, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-a-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-a-typedarray-throws.js
new file mode 100644
index 0000000000..8fc491f329
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-a-typedarray-throws.js
@@ -0,0 +1,44 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if the typedArray arg is not a TypedArray object
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+features: [Atomics.waitAsync, arrow-function, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync({}, 0, 0n, 0);
+}, '`Atomics.waitAsync({}, 0, 0n, 0)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync({}, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync({}, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-an-object-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-an-object-throws.js
new file mode 100644
index 0000000000..3f4caa0d05
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/not-an-object-throws.js
@@ -0,0 +1,64 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray arg is not an Object
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+features: [Atomics.waitAsync, Symbol, arrow-function, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(null, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(null, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(undefined, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(undefined, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(true, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(true, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(false, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(false, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync('***string***', poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync("***string***", poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(Symbol('***symbol***'), poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(Symbol("***symbol***"), poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-bufferdata-throws.js
new file mode 100644
index 0000000000..96e8e987b4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-bufferdata-throws.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  A null value for bufferData throws a TypeError
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+includes: [detachArrayBuffer.js]
+features: [Atomics.waitAsync, ArrayBuffer, Atomics, TypedArray, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(
+  new ArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i64a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout-agent.js
new file mode 100644
index 0000000000..298f98d34f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout-agent.js
@@ -0,0 +1,98 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  null timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return null;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return null;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, null).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, null).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout.js
new file mode 100644
index 0000000000..9f50139d06
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/null-for-timeout.js
@@ -0,0 +1,54 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  null timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return null;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return null;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, null).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, null).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, valueOf).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value is "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout-agent.js
new file mode 100644
index 0000000000..be0fece5ee
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout-agent.js
@@ -0,0 +1,107 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return 0;
+    }
+  };
+
+  const toString = {
+    toString() {
+      return "0";
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return 0;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, toString).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, toString).value);
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout.js
new file mode 100644
index 0000000000..d46f27436b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/object-for-timeout.js
@@ -0,0 +1,72 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt, arrow-function]
+flags: [async]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return 0;
+  }
+};
+
+const toString = {
+  toString() {
+    return '0';
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return 0;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, valueOf).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, toString).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, toString).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value is "timed-out"'
+);
+
+Promise.all([
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  Atomics.waitAsync(i64a, 0, 0n, toString).value,
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value
+]).then(outcomes => {
+  assert.sameValue(outcomes[0], 'timed-out', 'The value of outcomes[0] is "timed-out"');
+  assert.sameValue(outcomes[1], 'timed-out', 'The value of outcomes[1] is "timed-out"');
+  assert.sameValue(outcomes[2], 'timed-out', 'The value of outcomes[2] is "timed-out"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/out-of-range-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/out-of-range-index-throws.js
new file mode 100644
index 0000000000..e129569ae1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/out-of-range-index-throws.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a RangeError if value of index arg is out of range
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+    ...
+    2.Let accessIndex be ? ToIndex(requestIndex).
+    ...
+    5. If accessIndex ≥ length, throw a RangeError exception.
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, Infinity, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, Infinity, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, -1, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, -1, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, 4, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, 4, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i64a, 200, poisoned, poisoned);
+}, '`Atomics.waitAsync(i64a, 200, poisoned, poisoned)` throws a RangeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..abb3e8d0d1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws-agent.js
@@ -0,0 +1,86 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+  Let primValue be ? ToPrimitive(argument, hint Number).
+  Return ? ToNumber(primValue).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf() {
+      throw new Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]() {
+      throw new Error('passing a poisoned object using @@ToPrimitive');
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i64a, 0, 0n, poisonedValueOf);
+    } catch (error) {
+      status1 = 'poisonedValueOf';
+    }
+    try {
+      Atomics.waitAsync(i64a, 0, 0n, poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'poisonedToPrimitive';
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'poisonedValueOf',
+    '(await $262.agent.getReportAsync()) resolves to the value "poisonedValueOf"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'poisonedToPrimitive',
+    '(await $262.agent.getReportAsync()) resolves to the value "poisonedToPrimitive"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws.js
new file mode 100644
index 0000000000..a7878a5ba7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/poisoned-object-for-timeout-throws.js
@@ -0,0 +1,45 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+  Let primValue be ? ToPrimitive(argument, hint Number).
+  Return ? ToNumber(primValue).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('passing a poisoned object using @@ToPrimitive');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, 0n, poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, 0, 0n, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, 0n, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, 0, 0n, poisonedToPrimitive)` throws a Test262Error exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/shell.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/shell.js
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws-agent.js
new file mode 100644
index 0000000000..41cbde0555
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws-agent.js
@@ -0,0 +1,98 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i64a, Symbol('1'), poisonedValueOf, poisonedValueOf);
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i64a, Symbol('2'), poisonedToPrimitive, poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws.js
new file mode 100644
index 0000000000..aaa9ae80e9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-index-throws.js
@@ -0,0 +1,71 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, poisonedValueOf, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, poisonedValueOf, poisonedValueOf, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, Symbol('1'), poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, Symbol("1"), poisonedValueOf, poisonedValueOf)` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, Symbol('2'), poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, Symbol("2"), poisonedToPrimitive, poisonedToPrimitive)` throws a TypeError exception');
+
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..2ef1e36e59
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws-agent.js
@@ -0,0 +1,73 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i64a, 0, 0n, Symbol('1'));
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i64a, 0, 0n, Symbol('2'));
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws.js
new file mode 100644
index 0000000000..55dbafc489
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-timeout-throws.js
@@ -0,0 +1,52 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('passing a poisoned object using @@ToPrimitive');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, 0n, poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, 0, 0n, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, 0n, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, 0, 0n, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, 0, 0n, Symbol('foo'));
+}, '`Atomics.waitAsync(i64a, 0, 0n, Symbol("foo"))` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, 0, 0n, Symbol('foo'));
+}, '`Atomics.waitAsync(i64a, 0, 0n, Symbol("foo"))` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws-agent.js
new file mode 100644
index 0000000000..70bcc8d273
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws-agent.js
@@ -0,0 +1,89 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  5. Otherwise, let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf: function() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.waitAsync(i64a, 0, Symbol("1"), poisonedValueOf);
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i64a, 0, Symbol("2"), poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws.js
new file mode 100644
index 0000000000..552928e077
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/symbol-for-value-throws.js
@@ -0,0 +1,60 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  5. Otherwise, let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, BigInt]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, 0, poisonedValueOf, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i64a, 0, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, 0, poisonedToPrimitive, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, 0, Symbol("foo"), poisonedValueOf);
+}, '`Atomics.waitAsync(i64a, 0, Symbol("foo"), poisonedValueOf)` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i64a, 0, Symbol("foo"), poisonedToPrimitive);
+}, '`Atomics.waitAsync(i64a, 0, Symbol("foo"), poisonedToPrimitive)` throws a TypeError exception');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout-agent.js
new file mode 100644
index 0000000000..af48ef70d9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout-agent.js
@@ -0,0 +1,75 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  True timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return true;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return true;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, true).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout.js
new file mode 100644
index 0000000000..884acd3219
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/true-for-timeout.js
@@ -0,0 +1,65 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return true;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return true;
+  }
+};
+
+let outcomes = [];
+let lifespan = 1000;
+let start = $262.agent.monotonicNow();
+
+(function wait() {
+  let elapsed = $262.agent.monotonicNow() - start;
+
+  if (elapsed > lifespan) {
+    $DONE('Test timed out');
+    return;
+  }
+
+  if (outcomes.length) {
+    assert.sameValue(outcomes[0], 'timed-out', 'The value of outcomes[0] is "timed-out"');
+    assert.sameValue(outcomes[1], 'timed-out', 'The value of outcomes[1] is "timed-out"');
+    assert.sameValue(outcomes[2], 'timed-out', 'The value of outcomes[2] is "timed-out"');
+    $DONE();
+    return;
+  }
+
+  $262.agent.setTimeout(wait, 0);
+})();
+
+Promise.all([
+  Atomics.waitAsync(i64a, 0, 0n, true).value,
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value
+]).then(results => outcomes = results, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout-agent.js
new file mode 100644
index 0000000000..9ccc4e03c8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout-agent.js
@@ -0,0 +1,82 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const WAIT_INDEX = 0;
+const RUNNING = 1;
+const NUMAGENT = 2;
+const NOTIFYCOUNT = 2;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // undefined => NaN => +Infinity
+    $262.agent.report("A " + (await Atomics.waitAsync(i64a, 0, 0n, undefined).value));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // undefined timeout arg => NaN => +Infinity
+    $262.agent.report("B " + (await Atomics.waitAsync(i64a, 0, 0n).value));
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, BigInt(NUMAGENT)).then(async (agentCount) => {
+
+  assert.sameValue(
+    agentCount,
+    BigInt(NUMAGENT),
+    'The value of `agentCount` must return the same value returned by BigInt(NUMAGENT)'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, WAIT_INDEX, NOTIFYCOUNT),
+    NOTIFYCOUNT,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0, 2) must return the value of NOTIFYCOUNT'
+  );
+
+  const reports = [
+    await $262.agent.getReportAsync(),
+    await $262.agent.getReportAsync(),
+  ];
+
+  reports.sort();
+  assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+  assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout.js
new file mode 100644
index 0000000000..0b9deb11d2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-for-timeout.js
@@ -0,0 +1,51 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return undefined;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return undefined;
+  }
+};
+
+Promise.all([
+  Atomics.waitAsync(i64a, 0, 0n).value,
+  Atomics.waitAsync(i64a, 0, 0n, undefined).value,
+  Atomics.waitAsync(i64a, 0, 0n, valueOf).value,
+  Atomics.waitAsync(i64a, 0, 0n, toPrimitive).value
+]).then(outcomes => {
+  assert.sameValue(outcomes[0], 'ok', 'The value of outcomes[0] is "ok"');
+  assert.sameValue(outcomes[1], 'ok', 'The value of outcomes[1] is "ok"');
+  assert.sameValue(outcomes[2], 'ok', 'The value of outcomes[2] is "ok"');
+  assert.sameValue(outcomes[3], 'ok', 'The value of outcomes[3] is "ok"');
+}).then($DONE, $DONE);
+
+Atomics.notify(i64a, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-index-defaults-to-zero-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-index-defaults-to-zero-agent.js
new file mode 100644
index 0000000000..0eb729af68
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/undefined-index-defaults-to-zero-agent.js
@@ -0,0 +1,84 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined index arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+      ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const WAIT_INDEX = 0;
+const RUNNING = 1;
+const NUMAGENT = 2;
+const NOTIFYCOUNT = 2;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report("A " + (await Atomics.waitAsync(i64a, undefined, 0n).value));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    $262.agent.report("B " + (await Atomics.waitAsync(i64a, undefined, 0n).value));
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, BigInt(NUMAGENT)).then(async (agentCount) => {
+
+  assert.sameValue(
+    agentCount,
+    BigInt(NUMAGENT),
+    'The value of `agentCount` must return the same value returned by BigInt(NUMAGENT)'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, WAIT_INDEX, NOTIFYCOUNT),
+    NOTIFYCOUNT,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0, 2) must return the value of NOTIFYCOUNT'
+  );
+
+  const reports = [
+    await $262.agent.getReportAsync(),
+    await $262.agent.getReportAsync(),
+  ];
+
+  reports.sort();
+  assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+  assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal-agent.js
new file mode 100644
index 0000000000..6c0922fcf8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal-agent.js
@@ -0,0 +1,63 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  16. Let w be ! AtomicLoad(typedArray, i).
+  17. If v is not equal to w, then
+    a. Perform LeaveCriticalSection(WL).
+    b. If mode is sync, then
+      i. Return the String "not-equal".
+    c. Perform ! Call(capability.[[Resolve]], undefined, « "not-equal" »).
+    d. Return promiseCapability.[[Promise]].
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const value = 42n;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+    $262.agent.report(Atomics.store(i64a, 0, 42n));
+    $262.agent.report(Atomics.waitAsync(i64a, 0, 0n).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    value.toString(),
+    '(await $262.agent.getReportAsync()) must return the same value returned by value.toString()'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'not-equal',
+    '(await $262.agent.getReportAsync()) resolves to the value "not-equal"'
+  );
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0, 1),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0, 1) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal.js
new file mode 100644
index 0000000000..adc2bc69a2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/value-not-equal.js
@@ -0,0 +1,44 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  16. Let w be ! AtomicLoad(typedArray, i).
+  17. If v is not equal to w, then
+    a. Perform LeaveCriticalSection(WL).
+    b. If mode is sync, then
+      i. Return the String "not-equal".
+    c. Perform ! Call(capability.[[Resolve]], undefined, « "not-equal" »).
+    d. Return promiseCapability.[[Promise]].
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, BigInt, computed-property-names, Symbol, Symbol.toPrimitive, Atomics, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+const valueOf = {
+  valueOf() {
+    return undefined;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return undefined;
+  }
+};
+
+Promise.all([Atomics.store(i64a, 0, 42n), Atomics.waitAsync(i64a, 0, 0n).value]).then(outcomes => {
+  assert.sameValue(outcomes[0], 42n, 'The value of outcomes[0] is 42n');
+  assert.sameValue(outcomes[1], 'not-equal', 'The value of outcomes[1] is "not-equal"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/waiterlist-block-indexedposition-wake.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/waiterlist-block-indexedposition-wake.js
new file mode 100644
index 0000000000..bde4046ecd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/waiterlist-block-indexedposition-wake.js
@@ -0,0 +1,90 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Get the correct WaiterList
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  11. Let indexedPosition be (i × 4) + offset.
+  12. Let WL be GetWaiterList(block, indexedPosition).
+
+  GetWaiterList( block, i )
+
+  ...
+  4. Return the WaiterList that is referenced by the pair (block, i).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const NUMAGENT = 2;
+const RUNNING = 4;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // Wait on index 0
+    $262.agent.report(await Atomics.waitAsync(i64a, 0, 0n, Infinity).value);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    // Wait on index 2
+    $262.agent.report(await Atomics.waitAsync(i64a, 2, 0n, Infinity).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i64a = new BigInt64Array(
+  new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)
+);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, BigInt(NUMAGENT)).then(async (agentCount) => {
+
+  assert.sameValue(
+    agentCount,
+    BigInt(NUMAGENT),
+    'The value of `agentCount` must return the same value returned by BigInt(NUMAGENT)'
+  );
+
+  // Notify index 1, notifies nothing
+  assert.sameValue(Atomics.notify(i64a, 1), 0, 'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)), 1) must return 0');
+
+  // Notify index 3, notifies nothing
+  assert.sameValue(Atomics.notify(i64a, 3), 0, 'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)), 3) must return 0');
+
+  // Notify index 2, notifies 1
+  assert.sameValue(Atomics.notify(i64a, 2), 1, 'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)), 2) must return 1');
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+
+  // Notify index 0, notifies 1
+  assert.sameValue(Atomics.notify(i64a, 0), 1, 'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 5)), 0) must return 1');
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/was-woken-before-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/was-woken-before-timeout.js
new file mode 100644
index 0000000000..ba8807b68d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/bigint/was-woken-before-timeout.js
@@ -0,0 +1,53 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync returns the right result when it was awoken before
+  a timeout
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, BigInt, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.huge;
+const i64a = new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4));
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i64a = new BigInt64Array(sab);
+    Atomics.add(i64a, ${RUNNING}, 1n);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i64a, 0, 0n, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i64a, RUNNING, 1n).then(async agentCount => {
+  assert.sameValue(agentCount, 1n, 'The value of `agentCount` is 1n');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    1,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 1'
+  );
+
+  const lapse = await $262.agent.getReportAsync();
+  assert(lapse < TIMEOUT, 'The result of evaluating `(lapse < TIMEOUT)` is true');
+  const result = await $262.agent.getReportAsync();
+  assert.sameValue(result, 'ok', 'The value of `result` is "ok"');
+  assert.sameValue(result, 'ok', 'The value of `result` is "ok"');
+
+  assert.sameValue(
+    Atomics.notify(i64a, 0),
+    0,
+    'Atomics.notify(new BigInt64Array(new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 4)), 0) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/browser.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/descriptor.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/descriptor.js
new file mode 100644
index 0000000000..3d08175e3c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/descriptor.js
@@ -0,0 +1,24 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: Atomics.waitAsync property descriptor
+info: |
+  ES Section 17
+
+  Every other data property described in clauses 18 through 26 and in Annex
+  B.2 has the attributes { [[Writable]]: true, [[Enumerable]]: false,
+  [[Configurable]]: true } unless otherwise specified.
+includes: [propertyHelper.js]
+features: [Atomics.waitAsync, Atomics]
+---*/
+
+verifyProperty(Atomics, 'waitAsync', {
+  configurable: true,
+  writable: true,
+  enumerable: false,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout-agent.js
new file mode 100644
index 0000000000..05f0311793
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout-agent.js
@@ -0,0 +1,94 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return false;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return false;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, false).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, false).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout.js
new file mode 100644
index 0000000000..cfb66b3dd3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/false-for-timeout.js
@@ -0,0 +1,64 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return false;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return false;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, false).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, false).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, valueOf).value is "timed-out"'
+);
+
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, toPrimitive).value is "timed-out"'
+);
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0, false).value,
+    Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+    Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  ]).then(outcomes => {
+    assert.sameValue(outcomes[0], 'timed-out', 'The value of outcomes[0] is "timed-out"');
+    assert.sameValue(outcomes[1], 'timed-out', 'The value of outcomes[1] is "timed-out"');
+    assert.sameValue(outcomes[2], 'timed-out', 'The value of outcomes[2] is "timed-out"');
+  }).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/good-views.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/good-views.js
new file mode 100644
index 0000000000..343b706a41
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/good-views.js
@@ -0,0 +1,70 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test Atomics.waitAsync on arrays that allow atomic operations
+flags: [async]
+includes: [atomicsHelper.js, asyncHelpers.js]
+features: [Atomics.waitAsync, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+$262.agent.start(`
+  (async () => {
+    var sab = new SharedArrayBuffer(1024);
+    var good_indices = [ (view) => 0/-1, // -0
+                         (view) => '-0',
+                         (view) => view.length - 1,
+                         (view) => ({ valueOf: () => 0 }),
+                         (view) => ({ toString: () => '0', valueOf: false }) // non-callable valueOf triggers invocation of toString
+                       ];
+
+    var view = new Int32Array(sab, 32, 20);
+
+    view[0] = 0;
+    $262.agent.report("A " + (await Atomics.waitAsync(view, 0, 0, 0).value))
+    $262.agent.report("B " + (await Atomics.waitAsync(view, 0, 37, 0).value));
+
+    const results = [];
+    // In-bounds boundary cases for indexing
+    for ( let IdxGen of good_indices ) {
+        let Idx = IdxGen(view);
+        view.fill(0);
+        // Atomics.store() computes an index from Idx in the same way as other
+        // Atomics operations, not quite like view[Idx].
+        Atomics.store(view, Idx, 37);
+        results.push(await Atomics.waitAsync(view, Idx, 0).value);
+    }
+    $262.agent.report("C " + results.join(","));
+    $262.agent.leaving();
+  })();
+`);
+
+
+asyncTest(async () => {
+  const outcomes = [];
+
+  for (let i = 0; i < 3; i++) {
+    outcomes.push(await $262.agent.getReportAsync());
+  }
+
+  assert.sameValue(
+    outcomes[0],
+    'A timed-out',
+    'The value of outcomes[0] is "A timed-out"'
+  );
+
+  assert.sameValue(
+    outcomes[1],
+    'B not-equal',
+    'The value of outcomes[1] is "B not-equal"'
+  );
+  assert.sameValue(
+    outcomes[2],
+    'C not-equal,not-equal,not-equal,not-equal,not-equal',
+    'The value of outcomes[2] is "C not-equal,not-equal,not-equal,not-equal,not-equal"'
+  );
+});
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/implicit-infinity-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/implicit-infinity-for-timeout.js
new file mode 100644
index 0000000000..2c4baf0a85
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/implicit-infinity-for-timeout.js
@@ -0,0 +1,39 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+let {async, value} = Atomics.waitAsync(i32a, 0, 0);
+
+value.then(result => {
+
+  assert.sameValue(result, "ok", 'The value of `result` is "ok"');
+
+}, $DONE).then($DONE, $DONE);
+
+Atomics.notify(i32a, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/is-function.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/is-function.js
new file mode 100644
index 0000000000..96a8a74f60
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/is-function.js
@@ -0,0 +1,13 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: Atomics.waitAsync is callable
+features: [Atomics.waitAsync, Atomics]
+---*/
+
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/length.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/length.js
new file mode 100644
index 0000000000..b02c6027b3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/length.js
@@ -0,0 +1,34 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync.length is 4.
+info: |
+  Atomics.waitAsync ( ia, index, expect, timeout )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics.waitAsync, Atomics]
+---*/
+
+verifyProperty(Atomics.waitAsync, 'length', {
+  value: 4,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/name.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/name.js
new file mode 100644
index 0000000000..6a558f8464
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/name.js
@@ -0,0 +1,20 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync.name is "waitAsync".
+includes: [propertyHelper.js]
+features: [Atomics.waitAsync, Atomics]
+---*/
+
+verifyProperty(Atomics.waitAsync, 'name', {
+  value: 'waitAsync',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js
new file mode 100644
index 0000000000..3aac20d767
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js
@@ -0,0 +1,54 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  NaN timeout arg should result in an infinite timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, NaN).value);  // NaN => +Infinity
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+
+}).then($DONE, $DONE);
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-index-throws.js
new file mode 100644
index 0000000000..4d6c2b2526
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-index-throws.js
@@ -0,0 +1,45 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a RangeError is index < 0
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, -Infinity, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, -Infinity, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, -7.999, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, -7.999, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, -1, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, -1, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, -300, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, -300, poisoned, poisoned)` throws a RangeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout-agent.js
new file mode 100644
index 0000000000..317bcdf268
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout-agent.js
@@ -0,0 +1,52 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, -5).value); // -5 => 0
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout.js
new file mode 100644
index 0000000000..f2d611acee
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/negative-timeout.js
@@ -0,0 +1,34 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, destructuring-binding, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0, -1).value,
+  ]).then(([outcome]) => {
+    assert.sameValue(
+      outcome,
+      'timed-out',
+      'The value of `outcome` is "timed-out"'
+    );
+  }).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-no-operation.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-no-operation.js
new file mode 100644
index 0000000000..30462d4816
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-no-operation.js
@@ -0,0 +1,73 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync returns the right result when it timed out and that
+  the time to time out is reasonable.
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-add.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-add.js
new file mode 100644
index 0000000000..57cd10a192
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-add.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Add operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.add(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-and.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-and.js
new file mode 100644
index 0000000000..339ab3a329
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-and.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to And operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.and(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-compareExchange.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-compareExchange.js
new file mode 100644
index 0000000000..3802faddc4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-compareExchange.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to compareExchange operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.compareExchange(i32a, 0, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-exchange.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-exchange.js
new file mode 100644
index 0000000000..e68a1821f6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-exchange.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to exchange operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.exchange(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-or.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-or.js
new file mode 100644
index 0000000000..bec800415d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-or.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Or operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.or(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-store.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-store.js
new file mode 100644
index 0000000000..b60ce4f767
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-store.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Store operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.store(i32a, 0, 0b1010);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-sub.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-sub.js
new file mode 100644
index 0000000000..c60beab60e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-sub.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to Sub operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.sub(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-xor.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-xor.js
new file mode 100644
index 0000000000..f00bfadda5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/no-spurious-wakeup-on-xor.js
@@ -0,0 +1,74 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Waiter does not spuriously notify on index which is subject to xor operation
+info: |
+  AddWaiter ( WL, waiterRecord )
+
+  5. Append waiterRecord as the last element of WL.[[Waiters]]
+  6. If waiterRecord.[[Timeout]] is finite, then in parallel,
+    a. Wait waiterRecord.[[Timeout]] milliseconds.
+    b. Perform TriggerTimeout(WL, waiterRecord).
+
+  TriggerTimeout( WL, waiterRecord )
+
+  3. If waiterRecord is in WL.[[Waiters]], then
+    a. Set waiterRecord.[[Result]] to "timed-out".
+    b. Perform RemoveWaiter(WL, waiterRecord).
+    c. Perform NotifyWaiter(WL, waiterRecord).
+  4. Perform LeaveCriticalSection(WL).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.small;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  Atomics.xor(i32a, 0, 1);
+
+  const lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse >= TIMEOUT,
+    'The result of evaluating `(lapse >= TIMEOUT)` is true'
+  );
+
+  const result = await $262.agent.getReportAsync();
+
+  assert.sameValue(
+    result,
+    'timed-out',
+    'The value of `result` is "timed-out"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/non-int32-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/non-int32-typedarray-throws.js
new file mode 100644
index 0000000000..cd7fcb87e9
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/non-int32-typedarray-throws.js
@@ -0,0 +1,97 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray arg is not an Int32Array
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+
+features: [Atomics.waitAsync, Float32Array, Float64Array, Int8Array, TypedArray, Uint16Array, Uint8Array, Uint8ClampedArray, arrow-function, SharedArrayBuffer, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  const view = new Float64Array(
+    new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Float64Array( new SharedArrayBuffer(Float64Array.BYTES_PER_ELEMENT * 8) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Float32Array(
+    new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Float32Array( new SharedArrayBuffer(Float32Array.BYTES_PER_ELEMENT * 4) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+if (typeof Float16Array !== 'undefined') {
+  assert.throws(TypeError, function() {
+    const view = new Float16Array(
+      new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2)
+    );
+    Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+  }, '`const view = new Float16Array( new SharedArrayBuffer(Float16Array.BYTES_PER_ELEMENT * 2) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+}
+
+assert.throws(TypeError, () => {
+  const view = new Int16Array(
+    new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Int16Array( new SharedArrayBuffer(Int16Array.BYTES_PER_ELEMENT * 2) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Int8Array(
+    new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Int8Array( new SharedArrayBuffer(Int8Array.BYTES_PER_ELEMENT) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Uint32Array(
+    new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint32Array( new SharedArrayBuffer(Uint32Array.BYTES_PER_ELEMENT * 4) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Uint16Array(
+    new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint16Array( new SharedArrayBuffer(Uint16Array.BYTES_PER_ELEMENT * 2) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Uint8Array(
+    new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint8Array( new SharedArrayBuffer(Uint8Array.BYTES_PER_ELEMENT) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  const view = new Uint8ClampedArray(
+    new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT)
+  );
+  Atomics.waitAsync(view, poisoned, poisoned, poisoned);
+}, '`const view = new Uint8ClampedArray( new SharedArrayBuffer(Uint8ClampedArray.BYTES_PER_ELEMENT) ); Atomics.waitAsync(view, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/non-shared-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/non-shared-bufferdata-throws.js
new file mode 100644
index 0000000000..889bfd676e
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/non-shared-bufferdata-throws.js
@@ -0,0 +1,43 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray.buffer is not a SharedArrayBuffer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+
+features: [Atomics.waitAsync, ArrayBuffer, Atomics, TypedArray, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(i32a, 0, 0, 0);
+}, '`Atomics.waitAsync(i32a, 0, 0, 0)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(i32a, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/not-a-typedarray-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/not-a-typedarray-throws.js
new file mode 100644
index 0000000000..25be13fbbd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/not-a-typedarray-throws.js
@@ -0,0 +1,43 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if the typedArray arg is not a TypedArray object
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+features: [Atomics.waitAsync, arrow-function, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync({}, 0, 0, 0);
+}, '`Atomics.waitAsync({}, 0, 0, 0)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync({}, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync({}, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/not-an-object-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/not-an-object-throws.js
new file mode 100644
index 0000000000..9ea6b9f392
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/not-an-object-throws.js
@@ -0,0 +1,63 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if typedArray arg is not an Object
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+features: [Atomics.waitAsync, Symbol, arrow-function, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(null, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(null, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(undefined, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(undefined, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(true, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(true, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(false, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(false, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync('***string***', poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync("***string***", poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(Number.NEGATIVE_INFINITY, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+assert.throws(TypeError, () => {
+  Atomics.waitAsync(Symbol('***symbol***'), poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(Symbol("***symbol***"), poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/null-bufferdata-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-bufferdata-throws.js
new file mode 100644
index 0000000000..e5a8412140
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-bufferdata-throws.js
@@ -0,0 +1,50 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  A null value for bufferData throws a TypeError
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+
+  RequireInternalSlot ( O, internalSlot )
+
+  1. If Type(O) is not Object, throw a TypeError exception.
+  2. If O does not have an internalSlot internal slot, throw a TypeError exception.
+
+includes: [detachArrayBuffer.js]
+features: [Atomics.waitAsync, ArrayBuffer, Atomics, TypedArray]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new ArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+try {
+  $DETACHBUFFER(i32a.buffer); // Detaching a non-shared ArrayBuffer sets the [[ArrayBufferData]] value to null
+} catch (error) {
+  throw new Test262Error(`An unexpected error occurred when detaching ArrayBuffer: ${error.message}`);
+}
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, poisoned, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, poisoned, poisoned, poisoned)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout-agent.js
new file mode 100644
index 0000000000..09f8191896
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout-agent.js
@@ -0,0 +1,95 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  null timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return null;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return null;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, null).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, null).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout.js
new file mode 100644
index 0000000000..6567c2c7d8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/null-for-timeout.js
@@ -0,0 +1,56 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  null timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Null -> Return +0.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return null;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return null;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, null).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, null).value is "timed-out"'
+);
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, valueOf).value is "timed-out"'
+);
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, toPrimitive).value is "timed-out"'
+);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout-agent.js
new file mode 100644
index 0000000000..ae681bf391
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout-agent.js
@@ -0,0 +1,105 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return 0;
+    }
+  };
+
+  const toString = {
+    toString() {
+      return "0";
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return 0;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toString).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, toString).value);
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout.js
new file mode 100644
index 0000000000..cd1dc8f596
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/object-for-timeout.js
@@ -0,0 +1,73 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics, arrow-function]
+flags: [async]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return 0;
+  }
+};
+
+const toString = {
+  toString() {
+    return "0";
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return 0;
+  }
+};
+
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, valueOf).value is "timed-out"'
+);
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, toString).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, toString).value is "timed-out"'
+);
+assert.sameValue(
+  Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  'timed-out',
+  'The value of Atomics.waitAsync(i32a, 0, 0, toPrimitive).value is "timed-out"'
+);
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+    Atomics.waitAsync(i32a, 0, 0, toString).value,
+    Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  ]).then(outcomes => {
+    assert.sameValue(outcomes[0], "timed-out", 'The value of outcomes[0] is "timed-out"');
+    assert.sameValue(outcomes[1], "timed-out", 'The value of outcomes[1] is "timed-out"');
+    assert.sameValue(outcomes[2], "timed-out", 'The value of outcomes[2] is "timed-out"');
+  }).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/out-of-range-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/out-of-range-index-throws.js
new file mode 100644
index 0000000000..72ae3b0fb4
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/out-of-range-index-throws.js
@@ -0,0 +1,48 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a RangeError if value of index arg is out of range
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+    ...
+    2.Let accessIndex be ? ToIndex(requestIndex).
+    ...
+    5. If accessIndex ≥ length, throw a RangeError exception.
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisoned = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, Infinity, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, Infinity, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, -1, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, -1, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, 4, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, 4, poisoned, poisoned)` throws a RangeError exception');
+assert.throws(RangeError, function() {
+  Atomics.waitAsync(i32a, 200, poisoned, poisoned);
+}, '`Atomics.waitAsync(i32a, 200, poisoned, poisoned)` throws a RangeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..b2e606d77f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws-agent.js
@@ -0,0 +1,89 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  False timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+  Let primValue be ? ToPrimitive(argument, hint Number).
+  Return ? ToNumber(primValue).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf() {
+      throw new Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]() {
+      throw new Error('passing a poisoned object using @@ToPrimitive');
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i32a, 0, 0, poisonedValueOf);
+    } catch (error) {
+      status1 = 'poisonedValueOf';
+    }
+    try {
+      Atomics.waitAsync(i32a, 0, 0, poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'poisonedToPrimitive';
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'poisonedValueOf',
+    '(await $262.agent.getReportAsync()) resolves to the value "poisonedValueOf"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'poisonedToPrimitive',
+    '(await $262.agent.getReportAsync()) resolves to the value "poisonedToPrimitive"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws.js
new file mode 100644
index 0000000000..3a084108e5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/poisoned-object-for-timeout-throws.js
@@ -0,0 +1,49 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+  Let primValue be ? ToPrimitive(argument, hint Number).
+  Return ? ToNumber(primValue).
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('passing a poisoned object using @@ToPrimitive');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, 0, poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, 0, 0, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, 0, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, 0, 0, poisonedToPrimitive)` throws a Test262Error exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-ok.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-ok.js
new file mode 100644
index 0000000000..41fb6ae31c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-ok.js
@@ -0,0 +1,52 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync returns a result object containing a property named "value" whose value is a promise that resolves to "ok" and async is true.
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  13. Let promiseCapability be undefined.
+  14. If mode is async, then
+    a. Set promiseCapability to ! NewPromiseCapability(%Promise%).
+
+  ...
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"async"*, *true*).
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"value"*, _promiseCapability_.[[Promise]]).
+  Return _resultObject_.
+
+flags: [async]
+features: [Atomics.waitAsync, TypedArray, SharedArrayBuffer, destructuring-binding, Atomics, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+let {async, value} = Atomics.waitAsync(i32a, 0, 0, 1000);
+assert.sameValue(async, true, 'The value of `async` is true');
+assert(value instanceof Promise, 'The result of evaluating `(value instanceof Promise)` is true');
+assert.sameValue(
+  Object.getPrototypeOf(value),
+  Promise.prototype,
+  'Object.getPrototypeOf(value) must return the value of Promise.prototype'
+);
+
+value.then(outcome => {
+  assert.sameValue(outcome, "ok", 'The value of `outcome` is "ok"');
+}).then(() => $DONE(), $DONE);
+
+Atomics.add(i32a, 0, 1);
+Atomics.notify(i32a, 0, 1);
+
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-timed-out.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-timed-out.js
new file mode 100644
index 0000000000..9cd01f3200
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-promise-resolves-to-timed-out.js
@@ -0,0 +1,57 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync returns a result object containing a promise that resolves to "timed-out" and async is true.
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  13. Let promiseCapability be undefined.
+  14. If mode is async, then
+    a. Set promiseCapability to ! NewPromiseCapability(%Promise%).
+
+  ...
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"async"*, *true*).
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"value"*, _promiseCapability_.[[Promise]]).
+  Return _resultObject_.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, TypedArray, SharedArrayBuffer, destructuring-binding, Atomics, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+let {async, value} = Atomics.waitAsync(i32a, 0, 0, 1);
+let outcome = null;
+let lifespan = 1000;
+let start = $262.agent.monotonicNow();
+
+function wait() {
+  let elapsed = $262.agent.monotonicNow() - start;
+  if (elapsed > lifespan) {
+    $DONE("Test timed out");
+    return;
+  }
+  if (outcome === "timed-out") {
+    $DONE();
+    return;
+  }
+
+  $262.agent.setTimeout(wait, 0);
+}
+
+wait();
+
+value.then(result => (outcome = result), $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-not-equal.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-not-equal.js
new file mode 100644
index 0000000000..f981109bb7
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-not-equal.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync returns a result object containing a string "not-equal" and async is false.
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  13. Let promiseCapability be undefined.
+  14. If mode is async, then
+    a. Set promiseCapability to ! NewPromiseCapability(%Promise%).
+
+  ...
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"async"*, *true*).
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"value"*, _promiseCapability_.[[Promise]]).
+  Return _resultObject_.
+
+features: [Atomics.waitAsync, TypedArray, SharedArrayBuffer, destructuring-binding, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+let {async, value} = Atomics.waitAsync(i32a, 0, 1);
+
+assert.sameValue(async, false, 'The value of `async` is false');
+assert.sameValue(value, "not-equal", 'The value of `value` is "not-equal"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-timed-out.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-timed-out.js
new file mode 100644
index 0000000000..85fed2b5ad
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/returns-result-object-value-is-string-timed-out.js
@@ -0,0 +1,39 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Atomics.waitAsync returns a result object containing a string "not-equal" and async is false.
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  ...
+  13. Let promiseCapability be undefined.
+  14. If mode is async, then
+    a. Set promiseCapability to ! NewPromiseCapability(%Promise%).
+
+  ...
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"async"*, *true*).
+  Perform ! CreateDataPropertyOrThrow(_resultObject_, *"value"*, _promiseCapability_.[[Promise]]).
+  Return _resultObject_.
+
+features: [Atomics.waitAsync, TypedArray, SharedArrayBuffer, destructuring-binding, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 8)
+);
+
+let {async, value} = Atomics.waitAsync(i32a, 0, 0, 0);
+
+assert.sameValue(async, false, 'The value of `async` is false');
+assert.sameValue(value, "timed-out", 'The value of `value` is "timed-out"');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/shell.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/shell.js
new file mode 100644
index 0000000000..409797a047
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/shell.js
@@ -0,0 +1,457 @@
+// GENERATED, DO NOT EDIT
+// file: asyncHelpers.js
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A collection of assertion and wrapper functions for testing asynchronous built-ins.
+defines: [asyncTest]
+---*/
+
+function asyncTest(testFunc) {
+  if (!Object.hasOwn(globalThis, "$DONE")) {
+    throw new Test262Error("asyncTest called without async flag");
+  }
+  if (typeof testFunc !== "function") {
+    $DONE(new Test262Error("asyncTest called with non-function argument"));
+    return;
+  }
+  try {
+    testFunc().then(
+      function () {
+        $DONE();
+      },
+      function (error) {
+        $DONE(error);
+      }
+    );
+  } catch (syncError) {
+    $DONE(syncError);
+  }
+}
+
+assert.throwsAsync = async function (expectedErrorConstructor, func, message) {
+  var innerThenable;
+  if (message === undefined) {
+    message = "";
+  } else {
+    message += " ";
+  }
+  if (typeof func === "function") {
+    try {
+      innerThenable = func();
+      if (
+        innerThenable === null ||
+        typeof innerThenable !== "object" ||
+        typeof innerThenable.then !== "function"
+      ) {
+        message +=
+          "Expected to obtain an inner promise that would reject with a" +
+          expectedErrorConstructor.name +
+          " but result was not a thenable";
+        throw new Test262Error(message);
+      }
+    } catch (thrown) {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but an exception was thrown synchronously while obtaining the inner promise";
+      throw new Test262Error(message);
+    }
+  } else {
+    message +=
+      "assert.throwsAsync called with an argument that is not a function";
+    throw new Test262Error(message);
+  }
+
+  try {
+    return innerThenable.then(
+      function () {
+        message +=
+          "Expected a " +
+          expectedErrorConstructor.name +
+          " to be thrown asynchronously but no exception was thrown at all";
+        throw new Test262Error(message);
+      },
+      function (thrown) {
+        var expectedName, actualName;
+        if (typeof thrown !== "object" || thrown === null) {
+          message += "Thrown value was not an object!";
+          throw new Test262Error(message);
+        } else if (thrown.constructor !== expectedErrorConstructor) {
+          expectedName = expectedErrorConstructor.name;
+          actualName = thrown.constructor.name;
+          if (expectedName === actualName) {
+            message +=
+              "Expected a " +
+              expectedName +
+              " but got a different error constructor with the same name";
+          } else {
+            message +=
+              "Expected a " + expectedName + " but got a " + actualName;
+          }
+          throw new Test262Error(message);
+        }
+      }
+    );
+  } catch (thrown) {
+    if (typeof thrown !== "object" || thrown === null) {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but innerThenable synchronously threw a value that was not an object ";
+    } else {
+      message +=
+        "Expected a " +
+        expectedErrorConstructor.name +
+        " to be thrown asynchronously but a " +
+        thrown.constructor.name +
+        " was thrown synchronously";
+    }
+    throw new Test262Error(message);
+  }
+};
+
+// file: atomicsHelper.js
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: >
+    Collection of functions used to interact with Atomics.* operations across agent boundaries.
+defines:
+  - $262.agent.getReportAsync
+  - $262.agent.getReport
+  - $262.agent.safeBroadcastAsync
+  - $262.agent.safeBroadcast
+  - $262.agent.setTimeout
+  - $262.agent.tryYield
+  - $262.agent.trySleep
+---*/
+
+/**
+ * @return {String} A report sent from an agent.
+ */
+{
+  // This is only necessary because the original
+  // $262.agent.getReport API was insufficient.
+  //
+  // All runtimes currently have their own
+  // $262.agent.getReport which is wrong, so we
+  // will pave over it with a corrected version.
+  //
+  // Binding $262.agent is necessary to prevent
+  // breaking SpiderMonkey's $262.agent.getReport
+  let getReport = $262.agent.getReport.bind($262.agent);
+
+  $262.agent.getReport = function() {
+    var r;
+    while ((r = getReport()) == null) {
+      $262.agent.sleep(1);
+    }
+    return r;
+  };
+
+  if (this.setTimeout === undefined) {
+    (function(that) {
+      that.setTimeout = function(callback, delay) {
+        let p = Promise.resolve();
+        let start = Date.now();
+        let end = start + delay;
+        function check() {
+          if ((end - Date.now()) > 0) {
+            p.then(check);
+          }
+          else {
+            callback();
+          }
+        }
+        p.then(check);
+      }
+    })(this);
+  }
+
+  $262.agent.setTimeout = setTimeout;
+
+  $262.agent.getReportAsync = function() {
+    return new Promise(function(resolve) {
+      (function loop() {
+        let result = getReport();
+        if (!result) {
+          setTimeout(loop, 1000);
+        } else {
+          resolve(result);
+        }
+      })();
+    });
+  };
+}
+
+/**
+ *
+ * Share a given Int32Array or BigInt64Array to all running agents. Ensure that the
+ * provided TypedArray is a "shared typed array".
+ *
+ * NOTE: Migrating all tests to this API is necessary to prevent tests from hanging
+ * indefinitely when a SAB is sent to a worker but the code in the worker attempts to
+ * create a non-sharable TypedArray (something that is not Int32Array or BigInt64Array).
+ * When that scenario occurs, an exception is thrown and the agent worker can no
+ * longer communicate with any other threads that control the SAB. If the main
+ * thread happens to be spinning in the $262.agent.waitUntil() while loop, it will never
+ * meet its termination condition and the test will hang indefinitely.
+ *
+ * Because we've defined $262.agent.broadcast(SAB) in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md, there are host implementations
+ * that assume compatibility, which must be maintained.
+ *
+ *
+ * $262.agent.safeBroadcast(TA) should not be included in
+ * https://github.com/tc39/test262/blob/HEAD/INTERPRETING.md
+ *
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ */
+$262.agent.safeBroadcast = function(typedArray) {
+  let Constructor = Object.getPrototypeOf(typedArray).constructor;
+  let temp = new Constructor(
+    new SharedArrayBuffer(Constructor.BYTES_PER_ELEMENT)
+  );
+  try {
+    // This will never actually wait, but that's fine because we only
+    // want to ensure that this typedArray CAN be waited on and is shareable.
+    Atomics.wait(temp, 0, Constructor === Int32Array ? 1 : BigInt(1));
+  } catch (error) {
+    throw new Test262Error(`${Constructor.name} cannot be used as a shared typed array. (${error})`);
+  }
+
+  $262.agent.broadcast(typedArray.buffer);
+};
+
+$262.agent.safeBroadcastAsync = async function(ta, index, expected) {
+  await $262.agent.broadcast(ta.buffer);
+  await $262.agent.waitUntil(ta, index, expected);
+  await $262.agent.tryYield();
+  return await Atomics.load(ta, index);
+};
+
+
+/**
+ * With a given Int32Array or BigInt64Array, wait until the expected number of agents have
+ * reported themselves by calling:
+ *
+ *    Atomics.add(typedArray, index, 1);
+ *
+ * @param {(Int32Array|BigInt64Array)} typedArray An Int32Array or BigInt64Array with a SharedArrayBuffer
+ * @param {number} index    The index of which all agents will report.
+ * @param {number} expected The number of agents that are expected to report as active.
+ */
+$262.agent.waitUntil = function(typedArray, index, expected) {
+
+  var agents = 0;
+  while ((agents = Atomics.load(typedArray, index)) !== expected) {
+    /* nothing */
+  }
+  assert.sameValue(agents, expected, "Reporting number of 'agents' equals the value of 'expected'");
+};
+
+/**
+ * Timeout values used throughout the Atomics tests. All timeouts are specified in milliseconds.
+ *
+ * @property {number} yield Used for `$262.agent.tryYield`. Must not be used in other functions.
+ * @property {number} small Used when agents will always timeout and `Atomics.wake` is not part
+ *                          of the test semantics. Must be larger than `$262.agent.timeouts.yield`.
+ * @property {number} long  Used when some agents may timeout and `Atomics.wake` is called on some
+ *                          agents. The agents are required to wait and this needs to be observable
+ *                          by the main thread.
+ * @property {number} huge  Used when `Atomics.wake` is called on all waiting agents. The waiting
+ *                          must not timeout. The agents are required to wait and this needs to be
+ *                          observable by the main thread. All waiting agents must be woken by the
+ *                          main thread.
+ *
+ * Usage for `$262.agent.timeouts.small`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const TIMEOUT = $262.agent.timeouts.small;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agent was started and then try to yield control to increase
+ *   // the likelihood the agent has called `Atomics.wait` and is now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // The agent is expected to time out.
+ *   assert.sameValue($262.agent.getReport(), "timed-out");
+ *
+ *
+ * Usage for `$262.agent.timeouts.long`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.long;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake exactly one agent.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX, 1), 1);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until exactly one agent was woken.
+ *   // var woken = 0;
+ *   // while ((woken = Atomics.wake(i32a, WAIT_INDEX, 1)) !== 0) ;
+ *   // assert.sameValue(woken, 1);
+ *
+ *   // One agent was woken and the other one timed out.
+ *   const reports = [$262.agent.getReport(), $262.agent.getReport()];
+ *   assert(reports.includes("ok"));
+ *   assert(reports.includes("timed-out"));
+ *
+ *
+ * Usage for `$262.agent.timeouts.huge`:
+ *   const WAIT_INDEX = 0;
+ *   const RUNNING = 1;
+ *   const NUMAGENT = 2;
+ *   const TIMEOUT = $262.agent.timeouts.huge;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   for (let i = 0; i < NUMAGENT; i++) {
+ *     $262.agent.start(`
+ *       $262.agent.receiveBroadcast(function(sab) {
+ *         const i32a = new Int32Array(sab);
+ *         Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *         $262.agent.report(Atomics.wait(i32a, ${WAIT_INDEX}, 0, ${TIMEOUT}));
+ *
+ *         $262.agent.leaving();
+ *       });
+ *     `);
+ *   }
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until the agents were started and then try to yield control to increase
+ *   // the likelihood the agents have called `Atomics.wait` and are now waiting.
+ *   $262.agent.waitUntil(i32a, RUNNING, NUMAGENT);
+ *   $262.agent.tryYield();
+ *
+ *   // Wake all agents.
+ *   assert.sameValue(Atomics.wake(i32a, WAIT_INDEX), NUMAGENT);
+ *
+ *   // When it doesn't matter how many agents were woken at once, a while loop
+ *   // can be used to make the test more resilient against intermittent failures
+ *   // in case even though `tryYield` was called, the agents haven't started to
+ *   // wait.
+ *   //
+ *   // // Repeat until all agents were woken.
+ *   // for (var wokenCount = 0; wokenCount < NUMAGENT; ) {
+ *   //   var woken = 0;
+ *   //   while ((woken = Atomics.wake(i32a, WAIT_INDEX)) !== 0) ;
+ *   //   // Maybe perform an action on the woken agents here.
+ *   //   wokenCount += woken;
+ *   // }
+ *
+ *   // All agents were woken and none timeout.
+ *   for (var i = 0; i < NUMAGENT; i++) {
+ *     assert($262.agent.getReport(), "ok");
+ *   }
+ */
+$262.agent.timeouts = {
+  yield: 100,
+  small: 200,
+  long: 1000,
+  huge: 10000,
+};
+
+/**
+ * Try to yield control to the agent threads.
+ *
+ * Usage:
+ *   const VALUE = 0;
+ *   const RUNNING = 1;
+ *   const i32a = new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2));
+ *
+ *   $262.agent.start(`
+ *     $262.agent.receiveBroadcast(function(sab) {
+ *       const i32a = new Int32Array(sab);
+ *       Atomics.add(i32a, ${RUNNING}, 1);
+ *
+ *       Atomics.store(i32a, ${VALUE}, 1);
+ *
+ *       $262.agent.leaving();
+ *     });
+ *   `);
+ *   $262.agent.safeBroadcast(i32a.buffer);
+ *
+ *   // Wait until agent was started and then try to yield control.
+ *   $262.agent.waitUntil(i32a, RUNNING, 1);
+ *   $262.agent.tryYield();
+ *
+ *   // Note: This result is not guaranteed, but should hold in practice most of the time.
+ *   assert.sameValue(Atomics.load(i32a, VALUE), 1);
+ *
+ * The default implementation simply waits for `$262.agent.timeouts.yield` milliseconds.
+ */
+$262.agent.tryYield = function() {
+  $262.agent.sleep($262.agent.timeouts.yield);
+};
+
+/**
+ * Try to sleep the current agent for the given amount of milliseconds. It is acceptable,
+ * but not encouraged, to ignore this sleep request and directly continue execution.
+ *
+ * The default implementation calls `$262.agent.sleep(ms)`.
+ *
+ * @param {number} ms Time to sleep in milliseconds.
+ */
+$262.agent.trySleep = function(ms) {
+  $262.agent.sleep(ms);
+};
+
+// file: detachArrayBuffer.js
+// Copyright (C) 2016 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    A function used in the process of asserting correctness of TypedArray objects.
+
+    $262.detachArrayBuffer is defined by a host.
+defines: [$DETACHBUFFER]
+---*/
+
+function $DETACHBUFFER(buffer) {
+  if (!$262 || typeof $262.detachArrayBuffer !== "function") {
+    throw new Test262Error("No method available to detach an ArrayBuffer");
+  }
+  $262.detachArrayBuffer(buffer);
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws-agent.js
new file mode 100644
index 0000000000..937bad77ae
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws-agent.js
@@ -0,0 +1,100 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i32a, Symbol('1'), poisonedValueOf, poisonedValueOf);
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i32a, Symbol('2'), poisonedToPrimitive, poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws.js
new file mode 100644
index 0000000000..58127afa98
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-index-throws.js
@@ -0,0 +1,71 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+
+  ValidateAtomicAccess( typedArray, requestIndex )
+
+  2. Let accessIndex be ? ToIndex(requestIndex).
+
+  ToIndex ( value )
+
+  2. Else,
+    a. Let integerIndex be ? ToInteger(value).
+
+  ToInteger(value)
+
+  1. Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, poisonedValueOf, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, poisonedValueOf, poisonedValueOf, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, poisonedToPrimitive, poisonedToPrimitive, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, Symbol('1'), poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, Symbol("1"), poisonedValueOf, poisonedValueOf)` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, Symbol('2'), poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, Symbol("2"), poisonedToPrimitive, poisonedToPrimitive)` throws a TypeError exception');
+
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws-agent.js
new file mode 100644
index 0000000000..dc5c01c221
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws-agent.js
@@ -0,0 +1,77 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = '';
+    let status2 = '';
+
+    try {
+      Atomics.waitAsync(i32a, 0, 0, Symbol('1'));
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i32a, 0, 0, Symbol('2'));
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws.js
new file mode 100644
index 0000000000..1659f517e3
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-timeout-throws.js
@@ -0,0 +1,55 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error('passing a poisoned object using @@ToPrimitive');
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, 0, poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, 0, 0, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, 0, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, 0, 0, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, 0, 0, Symbol("foo"));
+}, '`Atomics.waitAsync(i32a, 0, 0, Symbol("foo"))` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, 0, 0, Symbol("foo"));
+}, '`Atomics.waitAsync(i32a, 0, 0, Symbol("foo"))` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws-agent.js
new file mode 100644
index 0000000000..4de2105353
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws-agent.js
@@ -0,0 +1,93 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  5. Otherwise, let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const poisonedValueOf = {
+    valueOf: function() {
+      throw new Test262Error('should not evaluate this code');
+    }
+  };
+
+  const poisonedToPrimitive = {
+    [Symbol.toPrimitive]: function() {
+      throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+    }
+  };
+
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    let status1 = "";
+    let status2 = "";
+
+    try {
+      Atomics.waitAsync(i32a, 0, Symbol("1"), poisonedValueOf);
+    } catch (error) {
+      status1 = 'A ' + error.name;
+    }
+    try {
+      Atomics.waitAsync(i32a, 0, Symbol("2"), poisonedToPrimitive);
+    } catch (error) {
+      status2 = 'B ' + error.name;
+    }
+
+    $262.agent.report(status1);
+    $262.agent.report(status2);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'A TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "A TypeError"'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'B TypeError',
+    '(await $262.agent.getReportAsync()) resolves to the value "B TypeError"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws.js
new file mode 100644
index 0000000000..1d0c98ad8c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/symbol-for-value-throws.js
@@ -0,0 +1,59 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if value arg is a Symbol
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  5. Otherwise, let v be ? ToInt32(value).
+
+  ToInt32(value)
+
+  1.Let number be ? ToNumber(argument).
+
+    Symbol --> Throw a TypeError exception.
+
+features: [Atomics.waitAsync, SharedArrayBuffer, Symbol, Symbol.toPrimitive, TypedArray, computed-property-names, Atomics]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const poisonedValueOf = {
+  valueOf() {
+    throw new Test262Error('should not evaluate this code');
+  }
+};
+
+const poisonedToPrimitive = {
+  [Symbol.toPrimitive]() {
+    throw new Test262Error("passing a poisoned object using @@ToPrimitive");
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, poisonedValueOf, poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, 0, poisonedValueOf, poisonedValueOf)` throws a Test262Error exception');
+
+assert.throws(Test262Error, function() {
+  Atomics.waitAsync(i32a, 0, poisonedToPrimitive, poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, 0, poisonedToPrimitive, poisonedToPrimitive)` throws a Test262Error exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, 0, Symbol("foo"), poisonedValueOf);
+}, '`Atomics.waitAsync(i32a, 0, Symbol("foo"), poisonedValueOf)` throws a TypeError exception');
+
+assert.throws(TypeError, function() {
+  Atomics.waitAsync(i32a, 0, Symbol("foo"), poisonedToPrimitive);
+}, '`Atomics.waitAsync(i32a, 0, Symbol("foo"), poisonedToPrimitive)` throws a TypeError exception');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout-agent.js
new file mode 100644
index 0000000000..240c3c07fa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout-agent.js
@@ -0,0 +1,76 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  True timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return true;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return true;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, true).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    '(await $262.agent.getReportAsync()) resolves to the value "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+
+}).then($DONE, $DONE);
+
+
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout.js
new file mode 100644
index 0000000000..86a2be28fa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/true-for-timeout.js
@@ -0,0 +1,66 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return true;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return true;
+  }
+};
+
+let outcomes = [];
+let lifespan = 1000;
+let start = $262.agent.monotonicNow();
+
+(function wait() {
+  let elapsed = $262.agent.monotonicNow() - start;
+  if (elapsed > lifespan) {
+    $DONE("Test timed out");
+    return;
+  }
+  if (outcomes.length) {
+    assert.sameValue(outcomes[0], 'timed-out', 'The value of outcomes[0] is "timed-out"');
+    assert.sameValue(outcomes[1], 'timed-out', 'The value of outcomes[1] is "timed-out"');
+    assert.sameValue(outcomes[2], 'timed-out', 'The value of outcomes[2] is "timed-out"');
+    $DONE();
+    return;
+  }
+
+  $262.agent.setTimeout(wait, 0);
+})();
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0, true).value,
+    Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+    Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  ]).then(results => (outcomes = results), $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js
new file mode 100644
index 0000000000..b50ef05dce
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js
@@ -0,0 +1,77 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const WAIT_INDEX = 0;
+const RUNNING = 1;
+const NUMAGENT = 2;
+const NOTIFYCOUNT = 2;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined => NaN => +Infinity
+    $262.agent.report("A " + (await Atomics.waitAsync(i32a, 0, 0, undefined).value));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined timeout arg => NaN => +Infinity
+    $262.agent.report("B " + (await Atomics.waitAsync(i32a, 0, 0).value));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, NUMAGENT).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, NUMAGENT, 'The value of `agentCount` is expected to equal the value of NUMAGENT');
+
+  assert.sameValue(
+    Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT),
+    NOTIFYCOUNT,
+    'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0, 2) must return the value of NOTIFYCOUNT'
+  );
+
+  const reports = [
+    await $262.agent.getReportAsync(),
+    await $262.agent.getReportAsync(),
+  ];
+
+  reports.sort();
+  assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+  assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout.js
new file mode 100644
index 0000000000..89038c7ab5
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-for-timeout.js
@@ -0,0 +1,54 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, computed-property-names, Symbol, Symbol.toPrimitive, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return undefined;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return undefined;
+  }
+};
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0).value,
+    Atomics.waitAsync(i32a, 0, 0, undefined).value,
+    Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+    Atomics.waitAsync(i32a, 0, 0, toPrimitive).value
+  ]).then(outcomes => {
+    assert.sameValue(outcomes[0], 'ok', 'The value of outcomes[0] is "ok"');
+    assert.sameValue(outcomes[1], 'ok', 'The value of outcomes[1] is "ok"');
+    assert.sameValue(outcomes[2], 'ok', 'The value of outcomes[2] is "ok"');
+    assert.sameValue(outcomes[3], 'ok', 'The value of outcomes[3] is "ok"');
+  }).then($DONE, $DONE);
+
+Atomics.notify(i32a, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-index-defaults-to-zero-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-index-defaults-to-zero-agent.js
new file mode 100644
index 0000000000..294e871035
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/undefined-index-defaults-to-zero-agent.js
@@ -0,0 +1,79 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined index arg is coerced to zero
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  2. Let i be ? ValidateAtomicAccess(typedArray, index).
+      ...
+      2.Let accessIndex be ? ToIndex(requestIndex).
+
+      9.If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+        ...
+          3.If bufferData is a Data Block, return false
+
+          If value is undefined, then
+          Let index be 0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const WAIT_INDEX = 0;
+const RUNNING = 1;
+const NUMAGENT = 2;
+const NOTIFYCOUNT = 2;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report("A " + (await Atomics.waitAsync(i32a, undefined, 0).value));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report("B " + (await Atomics.waitAsync(i32a, undefined, 0).value));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, NUMAGENT).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, NUMAGENT, 'The value of `agentCount` is expected to equal the value of NUMAGENT');
+
+  assert.sameValue(
+    Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT),
+    NOTIFYCOUNT,
+    'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0, 2) must return the value of NOTIFYCOUNT'
+  );
+
+  const reports = [
+    await $262.agent.getReportAsync(),
+    await $262.agent.getReportAsync(),
+  ];
+
+  reports.sort();
+  assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+  assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..4bdb4215ab
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  1. If waitable is not present, set waitable to false.
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+  3. Let typeName be typedArray.[[TypedArrayName]].
+  4. Let type be the Element Type value in Table 61 for typeName.
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+  6. Else,
+    a. If ! IsUnclampedIntegerElementType(type) is false and ! IsBigIntElementType(type) is false, throw a TypeError exception.
+  7. Assert: typedArray has a [[ViewedArrayBuffer]] internal slot.
+  8. Let buffer be typedArray.[[ViewedArrayBuffer]].
+  9. If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+  10. Return buffer.
+
+includes: [testTypedArray.js]
+features: [Atomics.waitAsync, Atomics, TypedArray, SharedArrayBuffer]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const index = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+var nonSharedArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (const nonSharedArrayType of nonSharedArrayTypes) {
+  const typedArray = new nonSharedArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.waitAsync(typedArray, index, 0, 0);
+  }, '`Atomics.waitAsync(typedArray, index, 0, 0)` throws a TypeError exception');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-timeout-coercion.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-timeout-coercion.js
new file mode 100644
index 0000000000..68297a551c
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-timeout-coercion.js
@@ -0,0 +1,53 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  TypedArray type is validated before `timeout` argument is coerced.
+info: |
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  1. If waitable is not present, set waitable to false.
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+  3. Let typeName be typedArray.[[TypedArrayName]].
+  4. Let type be the Element Type value in Table 61 for typeName.
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+  6. Else,
+    a. If ! IsUnclampedIntegerElementType(type) is false and ! IsBigIntElementType(type) is false, throw a TypeError exception.
+  7. Assert: typedArray has a [[ViewedArrayBuffer]] internal slot.
+  8. Let buffer be typedArray.[[ViewedArrayBuffer]].
+  9. If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+  10. Return buffer.
+
+features: [Atomics.waitAsync, Atomics, TypedArray, SharedArrayBuffer]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const timeout = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+const nonSharedArrayTypes = [
+  Int8Array, Uint8Array, Int16Array, Uint16Array, Uint32Array,
+  Uint8ClampedArray, Float32Array, Float64Array
+];
+
+for (const nonSharedArrayType of nonSharedArrayTypes) {
+  const typedArray = new nonSharedArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.waitAsync(typedArray, 0, 0, timeout);
+  }, '`Atomics.waitAsync(typedArray, 0, 0, timeout)` throws a TypeError exception');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..c329676b4d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,51 @@
+// |reftest| skip -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.notify
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray, true).
+
+  ValidateSharedIntegerTypedArray ( typedArray [ , waitable ] )
+
+  1. If waitable is not present, set waitable to false.
+  2. Perform ? RequireInternalSlot(typedArray, [[TypedArrayName]]).
+  3. Let typeName be typedArray.[[TypedArrayName]].
+  4. Let type be the Element Type value in Table 61 for typeName.
+  5. If waitable is true, then
+    a. If typeName is not "Int32Array" or "BigInt64Array", throw a TypeError exception.
+  6. Else,
+    a. If ! IsUnclampedIntegerElementType(type) is false and ! IsBigIntElementType(type) is false, throw a TypeError exception.
+  7. Assert: typedArray has a [[ViewedArrayBuffer]] internal slot.
+  8. Let buffer be typedArray.[[ViewedArrayBuffer]].
+  9. If IsSharedArrayBuffer(buffer) is false, throw a TypeError exception.
+  10. Return buffer.
+
+includes: [testTypedArray.js]
+features: [Atomics.waitAsync, Atomics, TypedArray, SharedArrayBuffer]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const value = {
+  valueOf() {
+    throw new Test262Error();
+  }
+};
+
+var nonSharedArrayTypes = typedArrayConstructors.filter(function(TA) { return TA !== Int32Array; });
+
+for (const nonSharedArrayType of nonSharedArrayTypes) {
+  const typedArray = new nonSharedArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.waitAsync(typedArray, 0, value, 0);
+  }, '`Atomics.waitAsync(typedArray, 0, value, 0)` throws a TypeError exception');
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal-agent.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal-agent.js
new file mode 100644
index 0000000000..852162a856
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal-agent.js
@@ -0,0 +1,67 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  16. Let w be ! AtomicLoad(typedArray, i).
+  17. If v is not equal to w, then
+    a. Perform LeaveCriticalSection(WL).
+    b. If mode is sync, then
+      i. Return the String "not-equal".
+    c. Perform ! Call(capability.[[Resolve]], undefined, « "not-equal" »).
+    d. Return promiseCapability.[[Promise]].
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const value = 42;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(function(sab) {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    $262.agent.report(Atomics.store(i32a, 0, ${value}));
+    $262.agent.report(Atomics.waitAsync(i32a, 0, 0).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    '42',
+    '(await $262.agent.getReportAsync()) resolves to the value "42"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'not-equal',
+    '(await $262.agent.getReportAsync()) resolves to the value "not-equal"'
+  );
+  assert.sameValue(
+    Atomics.notify(i32a, 0, 1),
+    0,
+    'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0, 1) must return 0'
+  );
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal.js
new file mode 100644
index 0000000000..324fc4fc90
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/value-not-equal.js
@@ -0,0 +1,50 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Returns "not-equal" when value arg does not match an index in the typedArray
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  16. Let w be ! AtomicLoad(typedArray, i).
+  17. If v is not equal to w, then
+    a. Perform LeaveCriticalSection(WL).
+    b. If mode is sync, then
+      i. Return the String "not-equal".
+    c. Perform ! Call(capability.[[Resolve]], undefined, « "not-equal" »).
+    d. Return promiseCapability.[[Promise]].
+
+flags: [async]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, computed-property-names, Symbol, Symbol.toPrimitive, Atomics, arrow-function]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return undefined;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return undefined;
+  }
+};
+
+Promise.all([
+    Atomics.store(i32a, 0, 42),
+    Atomics.waitAsync(i32a, 0, 0).value,
+  ]).then(outcomes => {
+    assert.sameValue(outcomes[0], 42, 'The value of outcomes[0] is 42');
+    assert.sameValue(outcomes[1], 'not-equal', 'The value of outcomes[1] is "not-equal"');
+  }).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/waiterlist-block-indexedposition-wake.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/waiterlist-block-indexedposition-wake.js
new file mode 100644
index 0000000000..eaef023ecd
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/waiterlist-block-indexedposition-wake.js
@@ -0,0 +1,85 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Get the correct WaiterList
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  11. Let indexedPosition be (i × 4) + offset.
+  12. Let WL be GetWaiterList(block, indexedPosition).
+
+  GetWaiterList( block, i )
+
+  ...
+  4. Return the WaiterList that is referenced by the pair (block, i).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const NUMAGENT = 2;
+const RUNNING = 4;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // Wait on index 0
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, Infinity).value);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // Wait on index 2
+    $262.agent.report(await Atomics.waitAsync(i32a, 2, 0, Infinity).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, NUMAGENT).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, NUMAGENT, 'The value of `agentCount` is expected to equal the value of NUMAGENT');
+
+  // Notify index 1, notifies nothing
+  assert.sameValue(Atomics.notify(i32a, 1), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)), 1) must return 0');
+
+  // Notify index 3, notifies nothing
+  assert.sameValue(Atomics.notify(i32a, 3), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)), 3) must return 0');
+
+  // Notify index 2, notifies 1
+  assert.sameValue(Atomics.notify(i32a, 2), 1, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)), 2) must return 1');
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+
+  // Notify index 0, notifies 1
+  assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 5)), 0) must return 1');
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/waitAsync/was-woken-before-timeout.js b/js/src/tests/test262/built-ins/Atomics/waitAsync/was-woken-before-timeout.js
new file mode 100644
index 0000000000..e45f0ef896
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/waitAsync/was-woken-before-timeout.js
@@ -0,0 +1,55 @@
+// |reftest| skip async -- Atomics.waitAsync is not supported
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Test that Atomics.waitAsync returns the right result when it was awoken before
+  a timeout
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics, arrow-function, async-functions]
+---*/
+assert.sameValue(typeof Atomics.waitAsync, 'function', 'The value of `typeof Atomics.waitAsync` is "function"');
+
+const RUNNING = 1;
+const TIMEOUT = $262.agent.timeouts.huge;
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    const before = $262.agent.monotonicNow();
+    const unpark = await Atomics.waitAsync(i32a, 0, 0, ${TIMEOUT}).value;
+    const duration = $262.agent.monotonicNow() - before;
+
+    $262.agent.report(duration);
+    $262.agent.report(unpark);
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1, 'The value of `agentCount` is 1');
+  assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 1');
+
+  let lapse = await $262.agent.getReportAsync();
+
+  assert(
+    lapse < TIMEOUT,
+    'The result of evaluating `(lapse < TIMEOUT)` is true'
+  );
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    '(await $262.agent.getReportAsync()) resolves to the value "ok"'
+  );
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)), 0) must return 0');
+}).then($DONE, $DONE);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bad-range.js b/js/src/tests/test262/built-ins/Atomics/xor/bad-range.js
new file mode 100644
index 0000000000..a0f267a353
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bad-range.js
@@ -0,0 +1,25 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Test range checking of Atomics.xor on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var sab = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 2);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  let view = new TA(sab);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.xor(view, IdxGen(view), 0);
+    }, '`Atomics.xor(view, IdxGen(view), 0)` throws RangeError');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bigint/bad-range.js b/js/src/tests/test262/built-ins/Atomics/xor/bigint/bad-range.js
new file mode 100644
index 0000000000..08e2427d5f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bigint/bad-range.js
@@ -0,0 +1,24 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Test range checking of Atomics.xor on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var buffer = new SharedArrayBuffer(BigInt64Array.BYTES_PER_ELEMENT * 2);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  let view = new TA(buffer);
+  testWithAtomicsOutOfBoundsIndices(function(IdxGen) {
+    assert.throws(RangeError, function() {
+      Atomics.xor(view, IdxGen(view), 10);
+    }, '`Atomics.xor(view, IdxGen(view), 10)` throws RangeError');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bigint/browser.js b/js/src/tests/test262/built-ins/Atomics/xor/bigint/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bigint/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bigint/good-views.js b/js/src/tests/test262/built-ins/Atomics/xor/bigint/good-views.js
new file mode 100644
index 0000000000..786caaa99d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bigint/good-views.js
@@ -0,0 +1,105 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.xor
+description: Test Atomics.xor on arrays that allow atomic operations
+includes: [testAtomics.js, testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+// Make it interesting - use non-zero byteOffsets and non-zero indexes.
+// And again
+// In-bounds boundary cases for indexing
+// Atomics.store() computes an index from Idx in the same way as other
+// Atomics operations, not quite like view[Idx].
+const sab = new SharedArrayBuffer(1024);
+const ab = new ArrayBuffer(16);
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const view = new TA(sab, 32, 20);
+  const control = new TA(ab, 0, 2);
+  view[8] = 0x33333333n;
+  control[0] = 0x33333333n;
+
+  assert.sameValue(
+    Atomics.xor(view, 8, 0x55555555n),
+    control[0],
+    'Atomics.xor(view, 8, 0x55555555n) returns the value of `control[0]` (0x33333333n)'
+  );
+
+  control[0] = 0x66666666n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x66666666n)'
+  );
+
+  assert.sameValue(
+    Atomics.xor(view, 8, 0xF0F0F0F0n),
+    control[0],
+    'Atomics.xor(view, 8, 0xF0F0F0F0) returns the value of `control[0]` (0x66666666n)'
+  );
+
+  control[0] = 0x96969696n;
+
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x96969696n)'
+  );
+
+  view[3] = -5n;
+  control[0] = -5n;
+
+  assert.sameValue(
+    Atomics.xor(view, 3, 0n),
+    control[0],
+    'Atomics.xor(view, 3, 0n) returns the value of `control[0]` (-5n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (-5n)'
+  );
+
+  control[0] = 12345n;
+  view[3] = 12345n;
+
+  assert.sameValue(
+    Atomics.xor(view, 3, 0n),
+    control[0],
+    'Atomics.xor(view, 3, 0n) returns the value of `control[0]` (12345n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (12345n)'
+  );
+
+  control[0] = 123456789n;
+  view[3] = 123456789n;
+
+  assert.sameValue(
+    Atomics.xor(view, 3, 0n),
+    control[0],
+    'Atomics.xor(view, 3, 0n) returns the value of `control[0]` (123456789n)'
+  );
+
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (123456789n)'
+  );
+
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0n);
+    Atomics.store(view, Idx, 37n);
+    assert.sameValue(Atomics.xor(view, Idx, 0n), 37n, 'Atomics.xor(view, Idx, 0n) returns 37n');
+  });
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bigint/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/xor/bigint/non-shared-bufferdata.js
new file mode 100644
index 0000000000..75843f227d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bigint/non-shared-bufferdata.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-atomics.xor
+description: >
+  Atomics.xor will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testBigIntTypedArray.js]
+features: [ArrayBuffer, Atomics, BigInt, TypedArray]
+---*/
+testWithBigIntTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+  assert.sameValue(Atomics.xor(view, 0, 1n), 0n, 'Atomics.xor(view, 0, 1n) returns 0n');
+  assert.sameValue(Atomics.load(view, 0), 1n, 'Atomics.load(view, 0) returns 1n');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/bigint/shell.js b/js/src/tests/test262/built-ins/Atomics/xor/bigint/shell.js
new file mode 100644
index 0000000000..90ee9c114d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/bigint/shell.js
@@ -0,0 +1,42 @@
+// GENERATED, DO NOT EDIT
+// file: testBigIntTypedArray.js
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: |
+    Collection of functions used to assert the correctness of BigInt TypedArray objects.
+defines:
+  - TypedArray
+  - testWithBigIntTypedArrayConstructors
+---*/
+
+/**
+ * The %TypedArray% intrinsic constructor function.
+ */
+var TypedArray = Object.getPrototypeOf(Int8Array);
+
+/**
+ * Calls the provided function for every typed array constructor.
+ *
+ * @param {typedArrayConstructorCallback} f - the function to call for each typed array constructor.
+ * @param {Array} selected - An optional Array with filtered typed arrays
+ */
+function testWithBigIntTypedArrayConstructors(f, selected) {
+  /**
+   * Array containing every BigInt typed array constructor.
+   */
+  var constructors = selected || [
+    BigInt64Array,
+    BigUint64Array
+  ];
+
+  for (var i = 0; i < constructors.length; ++i) {
+    var constructor = constructors[i];
+    try {
+      f(constructor);
+    } catch (e) {
+      e.message += " (Testing with " + constructor.name + ".)";
+      throw e;
+    }
+  }
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/browser.js b/js/src/tests/test262/built-ins/Atomics/xor/browser.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/browser.js
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/descriptor.js b/js/src/tests/test262/built-ins/Atomics/xor/descriptor.js
new file mode 100644
index 0000000000..7ea7b10e0d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/descriptor.js
@@ -0,0 +1,18 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: Testing descriptor property of Atomics.xor
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics, 'xor', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/expected-return-value.js b/js/src/tests/test262/built-ins/Atomics/xor/expected-return-value.js
new file mode 100644
index 0000000000..2ed347846f
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/expected-return-value.js
@@ -0,0 +1,49 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2018 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Atomics.xor returns the value that existed at the
+  index prior to the operation.
+info: |
+  Atomics.xor( typedArray, index, value )
+
+  1. Return ? AtomicReadModifyWrite(typedArray, index, value, xor).
+
+  AtomicReadModifyWrite( typedArray, index, value, op )
+
+  ...
+  9. Return GetModifySetValueInBuffer(buffer, indexedPosition,
+                                      elementType, v, op).
+
+
+  GetModifySetValueInBuffer( arrayBuffer,
+    byteIndex, type, value, op [ , isLittleEndian ] )
+
+  ...
+  16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
+
+features: [Atomics, SharedArrayBuffer, TypedArray]
+---*/
+
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+const a = 0b00000001000000001000000010000001;
+const b = 0b00000001111111111000000011111111;
+const c = 0b00000000111111110000000001111110;
+
+i32a[0] = a;
+
+assert.sameValue(
+  Atomics.xor(i32a, 0, b),
+  a,
+  'Atomics.xor(i32a, 0, b) returns the value of `a` (0b00000001000000001000000010000001)'
+);
+
+assert.sameValue(i32a[0], c, 'The value of i32a[0] equals the value of `c` (0b00000000111111110000000001111110)');
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/good-views.js b/js/src/tests/test262/built-ins/Atomics/xor/good-views.js
new file mode 100644
index 0000000000..6c70e71b28
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/good-views.js
@@ -0,0 +1,85 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: Test Atomics.xor on arrays that allow atomic operations
+includes: [testAtomics.js, testTypedArray.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+var sab = new SharedArrayBuffer(1024);
+var ab = new ArrayBuffer(16);
+var views = nonClampedIntArrayConstructors.slice();
+
+testWithTypedArrayConstructors(function(TA) {
+  // Make it interesting - use non-zero byteOffsets and non-zero indexes.
+
+  var view = new TA(sab, 32, 20);
+  var control = new TA(ab, 0, 2);
+
+  view[8] = 0x33333333;
+  control[0] = 0x33333333;
+  assert.sameValue(Atomics.xor(view, 8, 0x55555555), control[0],
+    'Atomics.xor(view, 8, 0x55555555) returns the value of `control[0]` (0x33333333)');
+
+  control[0] = 0x66666666;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x66666666)'
+  );
+  assert.sameValue(Atomics.xor(view, 8, 0xF0F0F0F0), control[0],
+    'Atomics.xor(view, 8, 0xF0F0F0F0) returns the value of `control[0]` (0x66666666)');
+
+  control[0] = 0x96969696;
+  assert.sameValue(
+    view[8],
+    control[0],
+    'The value of view[8] equals the value of `control[0]` (0x96969696)'
+  );
+
+  view[3] = -5;
+  control[0] = -5;
+  assert.sameValue(Atomics.xor(view, 3, 0), control[0],
+    'Atomics.xor(view, 3, 0) returns the value of `control[0]` (-5)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (-5)'
+  );
+
+  control[0] = 12345;
+  view[3] = 12345;
+  assert.sameValue(Atomics.xor(view, 3, 0), control[0],
+    'Atomics.xor(view, 3, 0) returns the value of `control[0]` (12345)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (12345)'
+  );
+
+  // And again
+  control[0] = 123456789;
+  view[3] = 123456789;
+  assert.sameValue(Atomics.xor(view, 3, 0), control[0],
+    'Atomics.xor(view, 3, 0) returns the value of `control[0]` (123456789)');
+  assert.sameValue(
+    view[3],
+    control[0],
+    'The value of view[3] equals the value of `control[0]` (123456789)'
+  );
+
+  // In-bounds boundary cases for indexing
+  testWithAtomicsInBoundsIndices(function(IdxGen) {
+    let Idx = IdxGen(view);
+    view.fill(0);
+    // Atomics.store() computes an index from Idx in the same way as other
+    // Atomics operations, not quite like view[Idx].
+    Atomics.store(view, Idx, 37);
+    assert.sameValue(Atomics.xor(view, Idx, 0), 37, 'Atomics.xor(view, Idx, 0) returns 37');
+  });
+}, views);
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/length.js b/js/src/tests/test262/built-ins/Atomics/xor/length.js
new file mode 100644
index 0000000000..1509b7b6f1
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/length.js
@@ -0,0 +1,36 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Atomics.xor.length is 3.
+info: |
+  Atomics.xor ( ia, index, val )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.xor, 'length', {
+  value: 3,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/name.js b/js/src/tests/test262/built-ins/Atomics/xor/name.js
new file mode 100644
index 0000000000..f28f95387d
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/name.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2015 André Bargull. All rights reserved.
+// Copyright (C) 2017 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Atomics.xor.name is "xor".
+includes: [propertyHelper.js]
+features: [Atomics]
+---*/
+
+verifyProperty(Atomics.xor, 'name', {
+  value: 'xor',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/non-shared-bufferdata.js b/js/src/tests/test262/built-ins/Atomics/xor/non-shared-bufferdata.js
new file mode 100644
index 0000000000..b8b4ec7bf2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/non-shared-bufferdata.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2020 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and will operate on TA when TA.buffer is not a SharedArrayBuffer
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithAtomicsFriendlyTypedArrayConstructors(TA => {
+  const view = new TA(
+    new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4)
+  );
+
+  assert.sameValue(Atomics.and(view, 0, 1), 0, 'Atomics.and(view, 0, 1) returns 0');
+  assert.sameValue(Atomics.load(view, 0), 0, 'Atomics.load(view, 0) returns 0');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/non-shared-int-views-throws.js b/js/src/tests/test262/built-ins/Atomics/xor/non-shared-int-views-throws.js
new file mode 100644
index 0000000000..d3f1dedbd8
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/non-shared-int-views-throws.js
@@ -0,0 +1,21 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.and
+description: >
+  Atomics.and throws when operating on non-sharable integer TypedArrays
+includes: [testTypedArray.js]
+features: [ArrayBuffer, Atomics, TypedArray]
+---*/
+testWithNonAtomicsFriendlyTypedArrayConstructors(TA => {
+  const buffer = new ArrayBuffer(TA.BYTES_PER_ELEMENT * 4);
+  const view = new TA(buffer);
+
+  assert.throws(TypeError, function() {
+    Atomics.and(view, 0, 1);
+  }, `Atomics.and(new ${TA.name}(buffer), 0, 1) throws TypeError`);
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/non-views.js b/js/src/tests/test262/built-ins/Atomics/xor/non-views.js
new file mode 100644
index 0000000000..64767f3236
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/non-views.js
@@ -0,0 +1,19 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2017 Mozilla Corporation.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  Test Atomics.xor on view values other than TypedArrays
+includes: [testAtomics.js]
+features: [ArrayBuffer, Atomics, DataView, SharedArrayBuffer, Symbol, TypedArray]
+---*/
+
+testWithAtomicsNonViewValues(function(view) {
+  assert.throws(TypeError, function() {
+    Atomics.xor(view, 0, 0);
+  }, '`Atomics.xor(view, 0, 0)` throws TypeError');
+});
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/not-a-constructor.js b/js/src/tests/test262/built-ins/Atomics/xor/not-a-constructor.js
new file mode 100644
index 0000000000..292954d861
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/not-a-constructor.js
@@ -0,0 +1,32 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Atomics.xor does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, Atomics, arrow-function, TypedArray, SharedArrayBuffer]
+---*/
+
+assert.sameValue(isConstructor(Atomics.xor), false, 'isConstructor(Atomics.xor) must return false');
+
+assert.throws(TypeError, () => {
+  new Atomics.xor(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)));
+}, '`new Atomics.xor(new Int32Array(new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT)))` throws TypeError');
+
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/shell.js b/js/src/tests/test262/built-ins/Atomics/xor/shell.js
new file mode 100644
index 0000000000..eda1477282
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/shell.js
@@ -0,0 +1,24 @@
+// GENERATED, DO NOT EDIT
+// file: isConstructor.js
+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: |
+    Test if a given function is a constructor function.
+defines: [isConstructor]
+features: [Reflect.construct]
+---*/
+
+function isConstructor(f) {
+    if (typeof f !== "function") {
+      throw new Test262Error("isConstructor invoked with a non-function value");
+    }
+
+    try {
+        Reflect.construct(function(){}, [], f);
+    } catch (e) {
+        return false;
+    }
+    return true;
+}
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-index-coercion.js b/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-index-coercion.js
new file mode 100644
index 0000000000..dc401d40f6
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-index-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  TypedArray type is validated before `index` argument is coerced.
+info: |
+  24.4.13 Atomics.xor ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, xor).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var index = {
+  valueOf() {
+    throw new Test262Error("index coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.xor(typedArray, index, 0);
+  });
+}
+
+reportCompare(0, 0);
diff --git a/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-value-coercion.js b/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-value-coercion.js
new file mode 100644
index 0000000000..b4ee63b0aa
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Atomics/xor/validate-arraytype-before-value-coercion.js
@@ -0,0 +1,43 @@
+// |reftest| skip-if(!this.hasOwnProperty('Atomics')) -- Atomics is not enabled unconditionally
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.xor
+description: >
+  TypedArray type is validated before `value` argument is coerced.
+info: |
+  24.4.13 Atomics.xor ( typedArray, index, value )
+    1. Return ? AtomicReadModifyWrite(typedArray, index, value, xor).
+
+  24.4.1.11 AtomicReadModifyWrite ( typedArray, index, value, op )
+    1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
+    ...
+
+  24.4.1.1 ValidateSharedIntegerTypedArray ( typedArray [ , onlyInt32 ] )
+    ...
+    4. Let typeName be typedArray.[[TypedArrayName]].
+    5. If onlyInt32 is true, then
+      a. If typeName is not "Int32Array", throw a TypeError exception.
+    6. Else,
+      a. If typeName is not "Int8Array", "Uint8Array", "Int16Array", "Uint16Array", "Int32Array",
+         or "Uint32Array", throw a TypeError exception.
+    ...
+includes: [testTypedArray.js]
+features: [Atomics, TypedArray]
+---*/
+
+var value = {
+  valueOf() {
+    throw new Test262Error("value coerced");
+  }
+};
+
+for (var badArrayType of nonAtomicsFriendlyTypedArrayConstructors) {
+  var typedArray = new badArrayType(new SharedArrayBuffer(8));
+  assert.throws(TypeError, function() {
+    Atomics.xor(typedArray, 0, value);
+  });
+}
+
+reportCompare(0, 0);