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diff --git a/library/std/src/sys_common/memchr.rs b/library/std/src/sys_common/memchr.rs
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+++ b/library/std/src/sys_common/memchr.rs
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+// Original implementation taken from rust-memchr.
+// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
+
+use crate::sys::memchr as sys;
+
+#[cfg(test)]
+mod tests;
+
+/// A safe interface to `memchr`.
+///
+/// Returns the index corresponding to the first occurrence of `needle` in
+/// `haystack`, or `None` if one is not found.
+///
+/// memchr reduces to super-optimized machine code at around an order of
+/// magnitude faster than `haystack.iter().position(|&b| b == needle)`.
+/// (See benchmarks.)
+///
+/// # Examples
+///
+/// This shows how to find the first position of a byte in a byte string.
+///
+/// ```ignore (cannot-doctest-private-modules)
+/// use memchr::memchr;
+///
+/// let haystack = b"the quick brown fox";
+/// assert_eq!(memchr(b'k', haystack), Some(8));
+/// ```
+#[inline]
+pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
+    sys::memchr(needle, haystack)
+}
+
+/// A safe interface to `memrchr`.
+///
+/// Returns the index corresponding to the last occurrence of `needle` in
+/// `haystack`, or `None` if one is not found.
+///
+/// # Examples
+///
+/// This shows how to find the last position of a byte in a byte string.
+///
+/// ```ignore (cannot-doctest-private-modules)
+/// use memchr::memrchr;
+///
+/// let haystack = b"the quick brown fox";
+/// assert_eq!(memrchr(b'o', haystack), Some(17));
+/// ```
+#[inline]
+pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
+    sys::memrchr(needle, haystack)
+}