Merging upstream version 1.67.1+dfsg1.

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

31 files changed, 1518 insertions, 1129 deletions

diff --git a/src/bootstrap/Cargo.lock b/src/bootstrap/Cargo.lock
index baecca44c..efe8ae316 100644
--- a/src/bootstrap/Cargo.lock
+++ b/src/bootstrap/Cargo.lock
@@ -12,15 +12,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "ansi_term"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d52a9bb7ec0cf484c551830a7ce27bd20d67eac647e1befb56b0be4ee39a55d2"
-dependencies = [
- "winapi",
-]
-
-[[package]]
 name = "autocfg"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -53,6 +44,7 @@ dependencies = [
  "hex",
  "ignore",
  "libc",
+ "object",
  "once_cell",
  "opener",
  "pretty_assertions",
@@ -107,18 +99,18 @@ checksum = "5827cebf4670468b8772dd191856768aedcb1b0278a04f989f7766351917b9dc"
 
 [[package]]
 name = "cpufeatures"
-version = "0.2.2"
+version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59a6001667ab124aebae2a495118e11d30984c3a653e99d86d58971708cf5e4b"
+checksum = "28d997bd5e24a5928dd43e46dc529867e207907fe0b239c3477d924f7f2ca320"
 dependencies = [
  "libc",
 ]
 
 [[package]]
 name = "crossbeam-channel"
-version = "0.5.4"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5aaa7bd5fb665c6864b5f963dd9097905c54125909c7aa94c9e18507cdbe6c53"
+checksum = "c2dd04ddaf88237dc3b8d8f9a3c1004b506b54b3313403944054d23c0870c521"
 dependencies = [
  "cfg-if",
  "crossbeam-utils",
@@ -126,9 +118,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-deque"
-version = "0.8.1"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6455c0ca19f0d2fbf751b908d5c55c1f5cbc65e03c4225427254b46890bdde1e"
+checksum = "715e8152b692bba2d374b53d4875445368fdf21a94751410af607a5ac677d1fc"
 dependencies = [
  "cfg-if",
  "crossbeam-epoch",
@@ -137,26 +129,24 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.8"
+version = "0.9.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1145cf131a2c6ba0615079ab6a638f7e1973ac9c2634fcbeaaad6114246efe8c"
+checksum = "01a9af1f4c2ef74bb8aa1f7e19706bc72d03598c8a570bb5de72243c7a9d9d5a"
 dependencies = [
  "autocfg",
  "cfg-if",
  "crossbeam-utils",
- "lazy_static",
  "memoffset",
  "scopeguard",
 ]
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.8"
+version = "0.8.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0bf124c720b7686e3c2663cf54062ab0f68a88af2fb6a030e87e30bf721fcb38"
+checksum = "4fb766fa798726286dbbb842f174001dab8abc7b627a1dd86e0b7222a95d929f"
 dependencies = [
  "cfg-if",
- "lazy_static",
 ]
 
 [[package]]
@@ -224,9 +214,9 @@ dependencies = [
 
 [[package]]
 name = "fd-lock"
-version = "3.0.6"
+version = "3.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e11dcc7e4d79a8c89b9ab4c6f5c30b1fc4a83c420792da3542fd31179ed5f517"
+checksum = "bb21c69b9fea5e15dbc1049e4b77145dd0ba1c84019c488102de0dc4ea4b0a27"
 dependencies = [
  "cfg-if",
  "rustix",
@@ -318,9 +308,13 @@ dependencies = [
 
 [[package]]
 name = "io-lifetimes"
-version = "0.7.2"
+version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24c3f4eff5495aee4c0399d7b6a0dc2b6e81be84242ffbfcf253ebacccc1d0cb"
+checksum = "a7d367024b3f3414d8e01f437f704f41a9f64ab36f9067fa73e526ad4c763c87"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
 
 [[package]]
 name = "itoa"
@@ -336,15 +330,15 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.126"
+version = "0.2.137"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "349d5a591cd28b49e1d1037471617a32ddcda5731b99419008085f72d5a53836"
+checksum = "fc7fcc620a3bff7cdd7a365be3376c97191aeaccc2a603e600951e452615bf89"
 
 [[package]]
 name = "linux-raw-sys"
-version = "0.0.46"
+version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d4d2456c373231a208ad294c33dc5bff30051eafd954cd4caae83a712b12854d"
+checksum = "8f9f08d8963a6c613f4b1a78f4f4a4dbfadf8e6545b2d72861731e4858b8b47f"
 
 [[package]]
 name = "log"
@@ -374,18 +368,18 @@ checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
 [[package]]
 name = "memoffset"
-version = "0.6.5"
+version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5aa361d4faea93603064a027415f07bd8e1d5c88c9fbf68bf56a285428fd79ce"
+checksum = "5de893c32cde5f383baa4c04c5d6dbdd735cfd4a794b0debdb2bb1b421da5ff4"
 dependencies = [
  "autocfg",
 ]
 
 [[package]]
 name = "ntapi"
-version = "0.3.7"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c28774a7fd2fbb4f0babd8237ce554b73af68021b5f695a3cebd6c59bac0980f"
+checksum = "bc51db7b362b205941f71232e56c625156eb9a929f8cf74a428fd5bc094a4afc"
 dependencies = [
  "winapi",
 ]
@@ -401,6 +395,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "object"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21158b2c33aa6d4561f1c0a6ea283ca92bc54802a93b263e910746d679a7eb53"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
 name = "once_cell"
 version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -433,14 +436,14 @@ checksum = "1df8c4ec4b0627e53bdf214615ad287367e482558cf84b109250b37464dc03ae"
 
 [[package]]
 name = "pretty_assertions"
-version = "0.7.2"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1cab0e7c02cf376875e9335e0ba1da535775beb5450d21e1dffca068818ed98b"
+checksum = "a25e9bcb20aa780fd0bb16b72403a9064d6b3f22f026946029acb941a50af755"
 dependencies = [
- "ansi_term",
  "ctor",
  "diff",
  "output_vt100",
+ "yansi",
 ]
 
 [[package]]
@@ -463,11 +466,10 @@ dependencies = [
 
 [[package]]
 name = "rayon"
-version = "1.5.3"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bd99e5772ead8baa5215278c9b15bf92087709e9c1b2d1f97cdb5a183c933a7d"
+checksum = "1e060280438193c554f654141c9ea9417886713b7acd75974c85b18a69a88e0b"
 dependencies = [
- "autocfg",
  "crossbeam-deque",
  "either",
  "rayon-core",
@@ -475,9 +477,9 @@ dependencies = [
 
 [[package]]
 name = "rayon-core"
-version = "1.9.3"
+version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "258bcdb5ac6dad48491bb2992db6b7cf74878b0384908af124823d118c99683f"
+checksum = "cac410af5d00ab6884528b4ab69d1e8e146e8d471201800fa1b4524126de6ad3"
 dependencies = [
  "crossbeam-channel",
  "crossbeam-deque",
@@ -519,9 +521,9 @@ checksum = "49b3de9ec5dc0a3417da371aab17d729997c15010e7fd24ff707773a33bddb64"
 
 [[package]]
 name = "rustix"
-version = "0.35.6"
+version = "0.36.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef258c11e17f5c01979a10543a30a4e12faef6aab217a74266e747eefa3aed88"
+checksum = "0b1fbb4dfc4eb1d390c02df47760bb19a84bb80b301ecc947ab5406394d8223e"
 dependencies = [
  "bitflags",
  "errno",
@@ -607,9 +609,9 @@ dependencies = [
 
 [[package]]
 name = "sysinfo"
-version = "0.24.2"
+version = "0.26.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a2809487b962344ca55d9aea565f9ffbcb6929780802217acc82561f6746770"
+checksum = "c375d5fd899e32847b8566e10598d6e9f1d9b55ec6de3cdf9e7da4bdc51371bc"
 dependencies = [
  "cfg-if",
  "core-foundation-sys",
@@ -717,46 +719,60 @@ checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
 [[package]]
 name = "windows-sys"
-version = "0.36.1"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ea04155a16a59f9eab786fe12a4a450e75cdb175f9e0d80da1e17db09f55b8d2"
+checksum = "5a3e1820f08b8513f676f7ab6c1f99ff312fb97b553d30ff4dd86f9f15728aa7"
 dependencies = [
+ "windows_aarch64_gnullvm",
  "windows_aarch64_msvc",
  "windows_i686_gnu",
  "windows_i686_msvc",
  "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
  "windows_x86_64_msvc",
 ]
 
 [[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.42.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41d2aa71f6f0cbe00ae5167d90ef3cfe66527d6f613ca78ac8024c3ccab9a19e"
+
+[[package]]
 name = "windows_aarch64_msvc"
-version = "0.36.1"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9bb8c3fd39ade2d67e9874ac4f3db21f0d710bee00fe7cab16949ec184eeaa47"
+checksum = "dd0f252f5a35cac83d6311b2e795981f5ee6e67eb1f9a7f64eb4500fbc4dcdb4"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.36.1"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "180e6ccf01daf4c426b846dfc66db1fc518f074baa793aa7d9b9aaeffad6a3b6"
+checksum = "fbeae19f6716841636c28d695375df17562ca208b2b7d0dc47635a50ae6c5de7"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.36.1"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2e7917148b2812d1eeafaeb22a97e4813dfa60a3f8f78ebe204bcc88f12f024"
+checksum = "84c12f65daa39dd2babe6e442988fc329d6243fdce47d7d2d155b8d874862246"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.36.1"
+version = "0.42.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf7b1b21b5362cbc318f686150e5bcea75ecedc74dd157d874d754a2ca44b0ed"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4dcd171b8776c41b97521e5da127a2d86ad280114807d0b2ab1e462bc764d9e1"
+checksum = "09d525d2ba30eeb3297665bd434a54297e4170c7f1a44cad4ef58095b4cd2028"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.36.1"
+version = "0.42.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c811ca4a8c853ef420abd8592ba53ddbbac90410fab6903b3e79972a631f7680"
+checksum = "f40009d85759725a34da6d89a94e63d7bdc50a862acf0dbc7c8e488f1edcb6f5"
 
 [[package]]
 name = "xattr"
@@ -775,3 +791,9 @@ checksum = "c179869f34fc7c01830d3ce7ea2086bc3a07e0d35289b667d0a8bf910258926c"
 dependencies = [
  "lzma-sys",
 ]
+
+[[package]]
+name = "yansi"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09041cd90cf85f7f8b2df60c646f853b7f535ce68f85244eb6731cf89fa498ec"
diff --git a/src/bootstrap/Cargo.toml b/src/bootstrap/Cargo.toml
index 95e711737..ccc7ec1fc 100644
--- a/src/bootstrap/Cargo.toml
+++ b/src/bootstrap/Cargo.toml
@@ -36,12 +36,13 @@ test = false
 
 [dependencies]
 cmake = "0.1.38"
-fd-lock = "3.0.6"
+fd-lock = "3.0.8"
 filetime = "0.2"
 getopts = "0.2.19"
 cc = "1.0.69"
 libc = "0.2"
 hex = "0.4"
+object = { version = "0.29.0", default-features = false, features = ["archive", "coff", "read_core", "unaligned"] }
 serde = { version = "1.0.8", features = ["derive"] }
 serde_json = "1.0.2"
 sha2 = "0.10"
@@ -54,7 +55,7 @@ xz2 = "0.1"
 walkdir = "2"
 
 # Dependencies needed by the build-metrics feature
-sysinfo = { version = "0.24.1", optional = true }
+sysinfo = { version = "0.26.0", optional = true }
 
 [target.'cfg(windows)'.dependencies.winapi]
 version = "0.3"
@@ -71,7 +72,7 @@ features = [
 ]
 
 [dev-dependencies]
-pretty_assertions = "0.7"
+pretty_assertions = "1.2"
 
 [features]
 build-metrics = ["sysinfo"]
diff --git a/src/bootstrap/bin/main.rs b/src/bootstrap/bin/main.rs
index 9b4861ccd..be69f819c 100644
--- a/src/bootstrap/bin/main.rs
+++ b/src/bootstrap/bin/main.rs
@@ -35,7 +35,7 @@ fn main() {
 
     // NOTE: Since `./configure` generates a `config.toml`, distro maintainers will see the
     // changelog warning, not the `x.py setup` message.
-    let suggest_setup = !config.config.exists() && !matches!(config.cmd, Subcommand::Setup { .. });
+    let suggest_setup = config.config.is_none() && !matches!(config.cmd, Subcommand::Setup { .. });
     if suggest_setup {
         println!("warning: you have not made a `config.toml`");
         println!(
diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 776d73b98..1d5260228 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -97,13 +97,7 @@ fn main() {
         // This... is a bit of a hack how we detect this. Ideally this
         // information should be encoded in the crate I guess? Would likely
         // require an RFC amendment to RFC 1513, however.
-        //
-        // `compiler_builtins` are unconditionally compiled with panic=abort to
-        // workaround undefined references to `rust_eh_unwind_resume` generated
-        // otherwise, see issue https://github.com/rust-lang/rust/issues/43095.
-        if crate_name == Some("panic_abort")
-            || crate_name == Some("compiler_builtins") && stage != "0"
-        {
+        if crate_name == Some("panic_abort") {
             cmd.arg("-C").arg("panic=abort");
         }
 
diff --git a/src/bootstrap/bin/rustdoc.rs b/src/bootstrap/bin/rustdoc.rs
index e69cab956..23828f475 100644
--- a/src/bootstrap/bin/rustdoc.rs
+++ b/src/bootstrap/bin/rustdoc.rs
@@ -55,13 +55,9 @@ fn main() {
         arg.push(&linker);
         cmd.arg(arg);
     }
-    if env::var_os("RUSTDOC_FUSE_LD_LLD").is_some() {
+    if let Ok(no_threads) = env::var("RUSTDOC_LLD_NO_THREADS") {
         cmd.arg("-Clink-arg=-fuse-ld=lld");
-        if cfg!(windows) {
-            cmd.arg("-Clink-arg=-Wl,/threads:1");
-        } else {
-            cmd.arg("-Clink-arg=-Wl,--threads=1");
-        }
+        cmd.arg(format!("-Clink-arg=-Wl,{}", no_threads));
     }
     // Cargo doesn't pass RUSTDOCFLAGS to proc_macros:
     // https://github.com/rust-lang/cargo/issues/4423
diff --git a/src/bootstrap/bootstrap.py b/src/bootstrap/bootstrap.py
index 57128685d..2d5018d93 100644
--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -441,6 +441,7 @@ class RustBuild(object):
 
             self.fix_bin_or_dylib("{}/bin/rustc".format(bin_root))
             self.fix_bin_or_dylib("{}/bin/rustdoc".format(bin_root))
+            self.fix_bin_or_dylib("{}/libexec/rust-analyzer-proc-macro-srv".format(bin_root))
             lib_dir = "{}/lib".format(bin_root)
             for lib in os.listdir(lib_dir):
                 if lib.endswith(".so"):
diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 8b144f146..8ee6d49da 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -2,14 +2,13 @@ use std::any::{type_name, Any};
 use std::cell::{Cell, RefCell};
 use std::collections::BTreeSet;
 use std::env;
-use std::ffi::{OsStr, OsString};
+use std::ffi::OsStr;
 use std::fmt::{Debug, Write};
-use std::fs::{self, File};
+use std::fs::{self};
 use std::hash::Hash;
-use std::io::{BufRead, BufReader, ErrorKind};
 use std::ops::Deref;
 use std::path::{Component, Path, PathBuf};
-use std::process::{Command, Stdio};
+use std::process::Command;
 use std::time::{Duration, Instant};
 
 use crate::cache::{Cache, Interned, INTERNER};
@@ -24,14 +23,12 @@ use crate::test;
 use crate::tool::{self, SourceType};
 use crate::util::{self, add_dylib_path, add_link_lib_path, exe, libdir, output, t};
 use crate::EXTRA_CHECK_CFGS;
-use crate::{check, Config};
-use crate::{compile, Crate};
+use crate::{check, compile, Crate};
 use crate::{Build, CLang, DocTests, GitRepo, Mode};
 
 pub use crate::Compiler;
 // FIXME: replace with std::lazy after it gets stabilized and reaches beta
-use once_cell::sync::{Lazy, OnceCell};
-use xz2::bufread::XzDecoder;
+use once_cell::sync::Lazy;
 
 pub struct Builder<'a> {
     pub build: &'a Build,
@@ -621,6 +618,8 @@ impl<'a> Builder<'a> {
                 check::CodegenBackend,
                 check::Clippy,
                 check::Miri,
+                check::CargoMiri,
+                check::MiroptTestTools,
                 check::Rls,
                 check::RustAnalyzer,
                 check::Rustfmt,
@@ -645,6 +644,7 @@ impl<'a> Builder<'a> {
                 test::CrateLibrustc,
                 test::CrateRustdoc,
                 test::CrateRustdocJsonTypes,
+                test::CrateJsonDocLint,
                 test::Linkcheck,
                 test::TierCheck,
                 test::ReplacePlaceholderTest,
@@ -753,6 +753,9 @@ impl<'a> Builder<'a> {
                 run::BuildManifest,
                 run::BumpStage0,
                 run::ReplaceVersionPlaceholder,
+                run::Miri,
+                run::CollectLicenseMetadata,
+                run::GenerateCopyright,
             ),
             // These commands either don't use paths, or they're special-cased in Build::build()
             Kind::Clean | Kind::Format | Kind::Setup => vec![],
@@ -816,7 +819,7 @@ impl<'a> Builder<'a> {
             Subcommand::Bench { ref paths, .. } => (Kind::Bench, &paths[..]),
             Subcommand::Dist { ref paths } => (Kind::Dist, &paths[..]),
             Subcommand::Install { ref paths } => (Kind::Install, &paths[..]),
-            Subcommand::Run { ref paths } => (Kind::Run, &paths[..]),
+            Subcommand::Run { ref paths, .. } => (Kind::Run, &paths[..]),
             Subcommand::Format { .. } => (Kind::Format, &[][..]),
             Subcommand::Clean { .. } | Subcommand::Setup { .. } => {
                 panic!()
@@ -850,241 +853,6 @@ impl<'a> Builder<'a> {
         StepDescription::run(v, self, paths);
     }
 
-    /// Modifies the interpreter section of 'fname' to fix the dynamic linker,
-    /// or the RPATH section, to fix the dynamic library search path
-    ///
-    /// This is only required on NixOS and uses the PatchELF utility to
-    /// change the interpreter/RPATH of ELF executables.
-    ///
-    /// Please see https://nixos.org/patchelf.html for more information
-    pub(crate) fn fix_bin_or_dylib(&self, fname: &Path) {
-        // FIXME: cache NixOS detection?
-        match Command::new("uname").arg("-s").stderr(Stdio::inherit()).output() {
-            Err(_) => return,
-            Ok(output) if !output.status.success() => return,
-            Ok(output) => {
-                let mut s = output.stdout;
-                if s.last() == Some(&b'\n') {
-                    s.pop();
-                }
-                if s != b"Linux" {
-                    return;
-                }
-            }
-        }
-
-        // If the user has asked binaries to be patched for Nix, then
-        // don't check for NixOS or `/lib`, just continue to the patching.
-        // NOTE: this intentionally comes after the Linux check:
-        // - patchelf only works with ELF files, so no need to run it on Mac or Windows
-        // - On other Unix systems, there is no stable syscall interface, so Nix doesn't manage the global libc.
-        if !self.config.patch_binaries_for_nix {
-            // Use `/etc/os-release` instead of `/etc/NIXOS`.
-            // The latter one does not exist on NixOS when using tmpfs as root.
-            const NIX_IDS: &[&str] = &["ID=nixos", "ID='nixos'", "ID=\"nixos\""];
-            let os_release = match File::open("/etc/os-release") {
-                Err(e) if e.kind() == ErrorKind::NotFound => return,
-                Err(e) => panic!("failed to access /etc/os-release: {}", e),
-                Ok(f) => f,
-            };
-            if !BufReader::new(os_release).lines().any(|l| NIX_IDS.contains(&t!(l).trim())) {
-                return;
-            }
-            if Path::new("/lib").exists() {
-                return;
-            }
-        }
-
-        // At this point we're pretty sure the user is running NixOS or using Nix
-        println!("info: you seem to be using Nix. Attempting to patch {}", fname.display());
-
-        // Only build `.nix-deps` once.
-        static NIX_DEPS_DIR: OnceCell<PathBuf> = OnceCell::new();
-        let mut nix_build_succeeded = true;
-        let nix_deps_dir = NIX_DEPS_DIR.get_or_init(|| {
-            // Run `nix-build` to "build" each dependency (which will likely reuse
-            // the existing `/nix/store` copy, or at most download a pre-built copy).
-            //
-            // Importantly, we create a gc-root called `.nix-deps` in the `build/`
-            // directory, but still reference the actual `/nix/store` path in the rpath
-            // as it makes it significantly more robust against changes to the location of
-            // the `.nix-deps` location.
-            //
-            // bintools: Needed for the path of `ld-linux.so` (via `nix-support/dynamic-linker`).
-            // zlib: Needed as a system dependency of `libLLVM-*.so`.
-            // patchelf: Needed for patching ELF binaries (see doc comment above).
-            let nix_deps_dir = self.out.join(".nix-deps");
-            const NIX_EXPR: &str = "
-            with (import <nixpkgs> {});
-            symlinkJoin {
-                name = \"rust-stage0-dependencies\";
-                paths = [
-                    zlib
-                    patchelf
-                    stdenv.cc.bintools
-                ];
-            }
-            ";
-            nix_build_succeeded = self.try_run(Command::new("nix-build").args(&[
-                Path::new("-E"),
-                Path::new(NIX_EXPR),
-                Path::new("-o"),
-                &nix_deps_dir,
-            ]));
-            nix_deps_dir
-        });
-        if !nix_build_succeeded {
-            return;
-        }
-
-        let mut patchelf = Command::new(nix_deps_dir.join("bin/patchelf"));
-        let rpath_entries = {
-            // ORIGIN is a relative default, all binary and dynamic libraries we ship
-            // appear to have this (even when `../lib` is redundant).
-            // NOTE: there are only two paths here, delimited by a `:`
-            let mut entries = OsString::from("$ORIGIN/../lib:");
-            entries.push(t!(fs::canonicalize(nix_deps_dir)));
-            entries.push("/lib");
-            entries
-        };
-        patchelf.args(&[OsString::from("--set-rpath"), rpath_entries]);
-        if !fname.extension().map_or(false, |ext| ext == "so") {
-            // Finally, set the correct .interp for binaries
-            let dynamic_linker_path = nix_deps_dir.join("nix-support/dynamic-linker");
-            // FIXME: can we support utf8 here? `args` doesn't accept Vec<u8>, only OsString ...
-            let dynamic_linker = t!(String::from_utf8(t!(fs::read(dynamic_linker_path))));
-            patchelf.args(&["--set-interpreter", dynamic_linker.trim_end()]);
-        }
-
-        self.try_run(patchelf.arg(fname));
-    }
-
-    pub(crate) fn download_component(&self, url: &str, dest_path: &Path, help_on_error: &str) {
-        self.verbose(&format!("download {url}"));
-        // Use a temporary file in case we crash while downloading, to avoid a corrupt download in cache/.
-        let tempfile = self.tempdir().join(dest_path.file_name().unwrap());
-        // While bootstrap itself only supports http and https downloads, downstream forks might
-        // need to download components from other protocols. The match allows them adding more
-        // protocols without worrying about merge conflicts if we change the HTTP implementation.
-        match url.split_once("://").map(|(proto, _)| proto) {
-            Some("http") | Some("https") => {
-                self.download_http_with_retries(&tempfile, url, help_on_error)
-            }
-            Some(other) => panic!("unsupported protocol {other} in {url}"),
-            None => panic!("no protocol in {url}"),
-        }
-        t!(std::fs::rename(&tempfile, dest_path));
-    }
-
-    fn download_http_with_retries(&self, tempfile: &Path, url: &str, help_on_error: &str) {
-        println!("downloading {}", url);
-        // Try curl. If that fails and we are on windows, fallback to PowerShell.
-        let mut curl = Command::new("curl");
-        curl.args(&[
-            "-#",
-            "-y",
-            "30",
-            "-Y",
-            "10", // timeout if speed is < 10 bytes/sec for > 30 seconds
-            "--connect-timeout",
-            "30", // timeout if cannot connect within 30 seconds
-            "--retry",
-            "3",
-            "-Sf",
-            "-o",
-        ]);
-        curl.arg(tempfile);
-        curl.arg(url);
-        if !self.check_run(&mut curl) {
-            if self.build.build.contains("windows-msvc") {
-                println!("Fallback to PowerShell");
-                for _ in 0..3 {
-                    if self.try_run(Command::new("PowerShell.exe").args(&[
-                        "/nologo",
-                        "-Command",
-                        "[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;",
-                        &format!(
-                            "(New-Object System.Net.WebClient).DownloadFile('{}', '{}')",
-                            url, tempfile.to_str().expect("invalid UTF-8 not supported with powershell downloads"),
-                        ),
-                    ])) {
-                        return;
-                    }
-                    println!("\nspurious failure, trying again");
-                }
-            }
-            if !help_on_error.is_empty() {
-                eprintln!("{}", help_on_error);
-            }
-            crate::detail_exit(1);
-        }
-    }
-
-    pub(crate) fn unpack(&self, tarball: &Path, dst: &Path, pattern: &str) {
-        println!("extracting {} to {}", tarball.display(), dst.display());
-        if !dst.exists() {
-            t!(fs::create_dir_all(dst));
-        }
-
-        // `tarball` ends with `.tar.xz`; strip that suffix
-        // example: `rust-dev-nightly-x86_64-unknown-linux-gnu`
-        let uncompressed_filename =
-            Path::new(tarball.file_name().expect("missing tarball filename")).file_stem().unwrap();
-        let directory_prefix = Path::new(Path::new(uncompressed_filename).file_stem().unwrap());
-
-        // decompress the file
-        let data = t!(File::open(tarball));
-        let decompressor = XzDecoder::new(BufReader::new(data));
-
-        let mut tar = tar::Archive::new(decompressor);
-        for member in t!(tar.entries()) {
-            let mut member = t!(member);
-            let original_path = t!(member.path()).into_owned();
-            // skip the top-level directory
-            if original_path == directory_prefix {
-                continue;
-            }
-            let mut short_path = t!(original_path.strip_prefix(directory_prefix));
-            if !short_path.starts_with(pattern) {
-                continue;
-            }
-            short_path = t!(short_path.strip_prefix(pattern));
-            let dst_path = dst.join(short_path);
-            self.verbose(&format!("extracting {} to {}", original_path.display(), dst.display()));
-            if !t!(member.unpack_in(dst)) {
-                panic!("path traversal attack ??");
-            }
-            let src_path = dst.join(original_path);
-            if src_path.is_dir() && dst_path.exists() {
-                continue;
-            }
-            t!(fs::rename(src_path, dst_path));
-        }
-        t!(fs::remove_dir_all(dst.join(directory_prefix)));
-    }
-
-    /// Returns whether the SHA256 checksum of `path` matches `expected`.
-    pub(crate) fn verify(&self, path: &Path, expected: &str) -> bool {
-        use sha2::Digest;
-
-        self.verbose(&format!("verifying {}", path.display()));
-        let mut hasher = sha2::Sha256::new();
-        // FIXME: this is ok for rustfmt (4.1 MB large at time of writing), but it seems memory-intensive for rustc and larger components.
-        // Consider using streaming IO instead?
-        let contents = if self.config.dry_run { vec![] } else { t!(fs::read(path)) };
-        hasher.update(&contents);
-        let found = hex::encode(hasher.finalize().as_slice());
-        let verified = found == expected;
-        if !verified && !self.config.dry_run {
-            println!(
-                "invalid checksum: \n\
-                found:    {found}\n\
-                expected: {expected}",
-            );
-        }
-        return verified;
-    }
-
     /// Obtain a compiler at a given stage and for a given host. Explicitly does
     /// not take `Compiler` since all `Compiler` instances are meant to be
     /// obtained through this function, since it ensures that they are valid
@@ -1289,7 +1057,7 @@ impl<'a> Builder<'a> {
     /// Note that this returns `None` if LLVM is disabled, or if we're in a
     /// check build or dry-run, where there's no need to build all of LLVM.
     fn llvm_config(&self, target: TargetSelection) -> Option<PathBuf> {
-        if self.config.llvm_enabled() && self.kind != Kind::Check && !self.config.dry_run {
+        if self.config.llvm_enabled() && self.kind != Kind::Check && !self.config.dry_run() {
             let llvm_config = self.ensure(native::Llvm { target });
             if llvm_config.is_file() {
                 return Some(llvm_config);
@@ -1298,19 +1066,6 @@ impl<'a> Builder<'a> {
         None
     }
 
-    /// Convenience wrapper to allow `builder.llvm_link_shared()` instead of `builder.config.llvm_link_shared(&builder)`.
-    pub(crate) fn llvm_link_shared(&self) -> bool {
-        Config::llvm_link_shared(self)
-    }
-
-    pub(crate) fn download_rustc(&self) -> bool {
-        Config::download_rustc(self)
-    }
-
-    pub(crate) fn initial_rustfmt(&self) -> Option<PathBuf> {
-        Config::initial_rustfmt(self)
-    }
-
     /// Prepares an invocation of `cargo` to be run.
     ///
     /// This will create a `Command` that represents a pending execution of
@@ -1342,7 +1097,13 @@ impl<'a> Builder<'a> {
             let my_out = match mode {
                 // This is the intended out directory for compiler documentation.
                 Mode::Rustc | Mode::ToolRustc => self.compiler_doc_out(target),
-                Mode::Std => out_dir.join(target.triple).join("doc"),
+                Mode::Std => {
+                    if self.config.cmd.json() {
+                        out_dir.join(target.triple).join("json-doc")
+                    } else {
+                        out_dir.join(target.triple).join("doc")
+                    }
+                }
                 _ => panic!("doc mode {:?} not expected", mode),
             };
             let rustdoc = self.rustdoc(compiler);
@@ -1641,7 +1402,7 @@ impl<'a> Builder<'a> {
         //
         // Only clear out the directory if we're compiling std; otherwise, we
         // should let Cargo take care of things for us (via depdep info)
-        if !self.config.dry_run && mode == Mode::Std && cmd == "build" {
+        if !self.config.dry_run() && mode == Mode::Std && cmd == "build" {
             self.clear_if_dirty(&out_dir, &self.rustc(compiler));
         }
 
@@ -2139,7 +1900,7 @@ impl<'a> Builder<'a> {
             (out, dur - deps)
         };
 
-        if self.config.print_step_timings && !self.config.dry_run {
+        if self.config.print_step_timings && !self.config.dry_run() {
             let step_string = format!("{:?}", step);
             let brace_index = step_string.find("{").unwrap_or(0);
             let type_string = type_name::<S>();
@@ -2205,6 +1966,24 @@ impl<'a> Builder<'a> {
 
         false
     }
+
+    pub(crate) fn maybe_open_in_browser<S: Step>(&self, path: impl AsRef<Path>) {
+        if self.was_invoked_explicitly::<S>(Kind::Doc) {
+            self.open_in_browser(path);
+        }
+    }
+
+    pub(crate) fn open_in_browser(&self, path: impl AsRef<Path>) {
+        if self.config.dry_run() || !self.config.cmd.open() {
+            return;
+        }
+
+        let path = path.as_ref();
+        self.info(&format!("Opening doc {}", path.display()));
+        if let Err(err) = opener::open(path) {
+            self.info(&format!("{}\n", err));
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/src/bootstrap/builder/tests.rs b/src/bootstrap/builder/tests.rs
index 88bbcc93d..5f21d2b00 100644
--- a/src/bootstrap/builder/tests.rs
+++ b/src/bootstrap/builder/tests.rs
@@ -1,5 +1,5 @@
 use super::*;
-use crate::config::{Config, TargetSelection};
+use crate::config::{Config, DryRun, TargetSelection};
 use std::thread;
 
 fn configure(cmd: &str, host: &[&str], target: &[&str]) -> Config {
@@ -10,7 +10,7 @@ fn configure_with_args(cmd: &[String], host: &[&str], target: &[&str]) -> Config
     let mut config = Config::parse(cmd);
     // don't save toolstates
     config.save_toolstates = None;
-    config.dry_run = true;
+    config.dry_run = DryRun::SelfCheck;
 
     // Ignore most submodules, since we don't need them for a dry run.
     // But make sure to check out the `doc` and `rust-analyzer` submodules, since some steps need them
diff --git a/src/bootstrap/cache.rs b/src/bootstrap/cache.rs
index be5c9bb07..05f25af68 100644
--- a/src/bootstrap/cache.rs
+++ b/src/bootstrap/cache.rs
@@ -89,16 +89,16 @@ impl<T: Internable + Hash> Hash for Interned<T> {
 
 impl<T: Internable + Deref> Deref for Interned<T> {
     type Target = T::Target;
-    fn deref(&self) -> &'static Self::Target {
+    fn deref(&self) -> &Self::Target {
         let l = T::intern_cache().lock().unwrap();
-        unsafe { mem::transmute::<&Self::Target, &'static Self::Target>(l.get(*self)) }
+        unsafe { mem::transmute::<&Self::Target, &Self::Target>(l.get(*self)) }
     }
 }
 
 impl<T: Internable + AsRef<U>, U: ?Sized> AsRef<U> for Interned<T> {
-    fn as_ref(&self) -> &'static U {
+    fn as_ref(&self) -> &U {
         let l = T::intern_cache().lock().unwrap();
-        unsafe { mem::transmute::<&U, &'static U>(l.get(*self).as_ref()) }
+        unsafe { mem::transmute::<&U, &U>(l.get(*self).as_ref()) }
     }
 }
 
diff --git a/src/bootstrap/cc_detect.rs b/src/bootstrap/cc_detect.rs
index 759a99c33..7128d542a 100644
--- a/src/bootstrap/cc_detect.rs
+++ b/src/bootstrap/cc_detect.rs
@@ -166,14 +166,7 @@ fn set_compiler(
         // compiler already takes into account the triple in question.
         t if t.contains("android") => {
             if let Some(ndk) = config.and_then(|c| c.ndk.as_ref()) {
-                let target = target
-                    .triple
-                    .replace("armv7neon", "arm")
-                    .replace("armv7", "arm")
-                    .replace("thumbv7neon", "arm")
-                    .replace("thumbv7", "arm");
-                let compiler = format!("{}-{}", target, compiler.clang());
-                cfg.compiler(ndk.join("bin").join(compiler));
+                cfg.compiler(ndk_compiler(compiler, &*target.triple, ndk));
             }
         }
 
@@ -225,8 +218,18 @@ fn set_compiler(
     }
 }
 
+pub(crate) fn ndk_compiler(compiler: Language, triple: &str, ndk: &Path) -> PathBuf {
+    let triple_translated = triple
+        .replace("armv7neon", "arm")
+        .replace("armv7", "arm")
+        .replace("thumbv7neon", "arm")
+        .replace("thumbv7", "arm");
+    let compiler = format!("{}-{}", triple_translated, compiler.clang());
+    ndk.join("bin").join(compiler)
+}
+
 /// The target programming language for a native compiler.
-enum Language {
+pub(crate) enum Language {
     /// The compiler is targeting C.
     C,
     /// The compiler is targeting C++.
diff --git a/src/bootstrap/channel.rs b/src/bootstrap/channel.rs
index 258352a21..eae81b9fc 100644
--- a/src/bootstrap/channel.rs
+++ b/src/bootstrap/channel.rs
@@ -13,8 +13,10 @@ use crate::util::output;
 use crate::util::t;
 use crate::Build;
 
+#[derive(Clone, Default)]
 pub enum GitInfo {
     /// This is not a git repository.
+    #[default]
     Absent,
     /// This is a git repository.
     /// If the info should be used (`ignore_git` is false), this will be
@@ -25,6 +27,7 @@ pub enum GitInfo {
     RecordedForTarball(Info),
 }
 
+#[derive(Clone)]
 pub struct Info {
     pub commit_date: String,
     pub sha: String,
diff --git a/src/bootstrap/check.rs b/src/bootstrap/check.rs
index 229851238..2e1bd8d6d 100644
--- a/src/bootstrap/check.rs
+++ b/src/bootstrap/check.rs
@@ -451,16 +451,16 @@ macro_rules! tool_check_step {
 }
 
 tool_check_step!(Rustdoc, "src/tools/rustdoc", "src/librustdoc", SourceType::InTree);
-// Clippy and Rustfmt are hybrids. They are external tools, but use a git subtree instead
+// Clippy, miri and Rustfmt are hybrids. They are external tools, but use a git subtree instead
 // of a submodule. Since the SourceType only drives the deny-warnings
 // behavior, treat it as in-tree so that any new warnings in clippy will be
 // rejected.
 tool_check_step!(Clippy, "src/tools/clippy", SourceType::InTree);
-// Miri on the other hand is treated as out of tree, since InTree also causes it to
-// be run as part of `check`, which can fail on platforms which libffi-sys has no support for.
-tool_check_step!(Miri, "src/tools/miri", SourceType::Submodule);
+tool_check_step!(Miri, "src/tools/miri", SourceType::InTree);
+tool_check_step!(CargoMiri, "src/tools/miri/cargo-miri", SourceType::InTree);
 tool_check_step!(Rls, "src/tools/rls", SourceType::InTree);
 tool_check_step!(Rustfmt, "src/tools/rustfmt", SourceType::InTree);
+tool_check_step!(MiroptTestTools, "src/tools/miropt-test-tools", SourceType::InTree);
 
 tool_check_step!(Bootstrap, "src/bootstrap", SourceType::InTree, false);
 
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index e02a10b81..0deed3f99 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -206,7 +206,6 @@ fn copy_third_party_objects(
     }
 
     if target == "x86_64-fortanix-unknown-sgx"
-        || target.contains("pc-windows-gnullvm")
         || builder.config.llvm_libunwind(target) == LlvmLibunwind::InTree
             && (target.contains("linux") || target.contains("fuchsia"))
     {
@@ -299,7 +298,9 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
     // Determine if we're going to compile in optimized C intrinsics to
     // the `compiler-builtins` crate. These intrinsics live in LLVM's
-    // `compiler-rt` repository.
+    // `compiler-rt` repository, but our `src/llvm-project` submodule isn't
+    // always checked out, so we need to conditionally look for this. (e.g. if
+    // an external LLVM is used we skip the LLVM submodule checkout).
     //
     // Note that this shouldn't affect the correctness of `compiler-builtins`,
     // but only its speed. Some intrinsics in C haven't been translated to Rust
@@ -310,15 +311,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
     // If `compiler-rt` is available ensure that the `c` feature of the
     // `compiler-builtins` crate is enabled and it's configured to learn where
     // `compiler-rt` is located.
-    let compiler_builtins_c_feature = if builder.config.optimized_compiler_builtins {
-        if !builder.is_rust_llvm(target) {
-            panic!(
-                "need a managed LLVM submodule for optimized intrinsics support; unset `llvm-config` or `optimized-compiler-builtins`"
-            );
-        }
-
-        builder.update_submodule(&Path::new("src").join("llvm-project"));
-        let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
+    let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
+    let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
         // Note that `libprofiler_builtins/build.rs` also computes this so if
         // you're changing something here please also change that.
         cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);
@@ -452,7 +446,7 @@ fn copy_sanitizers(
 ) -> Vec<PathBuf> {
     let runtimes: Vec<native::SanitizerRuntime> = builder.ensure(native::Sanitizers { target });
 
-    if builder.config.dry_run {
+    if builder.config.dry_run() {
         return Vec::new();
     }
 
@@ -769,10 +763,10 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
 
     cargo.env("CFG_LIBDIR_RELATIVE", libdir_relative);
 
-    if let Some(ref ver_date) = builder.rust_info.commit_date() {
+    if let Some(ref ver_date) = builder.rust_info().commit_date() {
         cargo.env("CFG_VER_DATE", ver_date);
     }
-    if let Some(ref ver_hash) = builder.rust_info.sha() {
+    if let Some(ref ver_hash) = builder.rust_info().sha() {
         cargo.env("CFG_VER_HASH", ver_hash);
     }
     if !builder.unstable_features() {
@@ -991,7 +985,7 @@ impl Step for CodegenBackend {
             compiler.stage, backend, &compiler.host, target
         ));
         let files = run_cargo(builder, cargo, vec![], &tmp_stamp, vec![], false);
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return;
         }
         let mut files = files.into_iter().filter(|f| {
@@ -1039,7 +1033,7 @@ fn copy_codegen_backends_to_sysroot(
     let dst = builder.sysroot_codegen_backends(target_compiler);
     t!(fs::create_dir_all(&dst), dst);
 
-    if builder.config.dry_run {
+    if builder.config.dry_run() {
         return;
     }
 
@@ -1127,13 +1121,18 @@ impl Step for Sysroot {
     fn run(self, builder: &Builder<'_>) -> Interned<PathBuf> {
         let compiler = self.compiler;
         let host_dir = builder.out.join(&compiler.host.triple);
-        let sysroot = if compiler.stage == 0 {
-            host_dir.join("stage0-sysroot")
-        } else if builder.download_rustc() {
-            host_dir.join("ci-rustc-sysroot")
-        } else {
-            host_dir.join(format!("stage{}", compiler.stage))
+
+        let sysroot_dir = |stage| {
+            if stage == 0 {
+                host_dir.join("stage0-sysroot")
+            } else if builder.download_rustc() && compiler.stage != builder.top_stage {
+                host_dir.join("ci-rustc-sysroot")
+            } else {
+                host_dir.join(format!("stage{}", stage))
+            }
         };
+        let sysroot = sysroot_dir(compiler.stage);
+
         let _ = fs::remove_dir_all(&sysroot);
         t!(fs::create_dir_all(&sysroot));
 
@@ -1144,9 +1143,15 @@ impl Step for Sysroot {
                 "Cross-compiling is not yet supported with `download-rustc`",
             );
 
-            // #102002, cleanup stage1 and stage0-sysroot folders when using download-rustc so people don't use old versions of the toolchain by accident.
-            let _ = fs::remove_dir_all(host_dir.join("stage1"));
-            let _ = fs::remove_dir_all(host_dir.join("stage0-sysroot"));
+            // #102002, cleanup old toolchain folders when using download-rustc so people don't use them by accident.
+            for stage in 0..=2 {
+                if stage != compiler.stage {
+                    let dir = sysroot_dir(stage);
+                    if !dir.ends_with("ci-rustc-sysroot") {
+                        let _ = fs::remove_dir_all(dir);
+                    }
+                }
+            }
 
             // Copy the compiler into the correct sysroot.
             let ci_rustc_dir =
@@ -1337,7 +1342,7 @@ impl Step for Assemble {
 
         if builder.config.rust_codegen_backends.contains(&INTERNER.intern_str("llvm")) {
             let llvm_config_bin = builder.ensure(native::Llvm { target: target_compiler.host });
-            if !builder.config.dry_run {
+            if !builder.config.dry_run() {
                 let llvm_bin_dir = output(Command::new(llvm_config_bin).arg("--bindir"));
                 let llvm_bin_dir = Path::new(llvm_bin_dir.trim());
 
@@ -1407,7 +1412,7 @@ pub fn run_cargo(
     additional_target_deps: Vec<(PathBuf, DependencyType)>,
     is_check: bool,
 ) -> Vec<PathBuf> {
-    if builder.config.dry_run {
+    if builder.config.dry_run() {
         return Vec::new();
     }
 
@@ -1547,7 +1552,7 @@ pub fn stream_cargo(
     cb: &mut dyn FnMut(CargoMessage<'_>),
 ) -> bool {
     let mut cargo = Command::from(cargo);
-    if builder.config.dry_run {
+    if builder.config.dry_run() {
         return true;
     }
     // Instruct Cargo to give us json messages on stdout, critically leaving
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index a8c403675..d8c15c76e 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -7,19 +7,19 @@ use std::cell::{Cell, RefCell};
 use std::cmp;
 use std::collections::{HashMap, HashSet};
 use std::env;
-use std::ffi::OsStr;
 use std::fmt;
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::str::FromStr;
 
-use crate::builder::{Builder, TaskPath};
+use crate::builder::TaskPath;
 use crate::cache::{Interned, INTERNER};
-use crate::channel::GitInfo;
+use crate::cc_detect::{ndk_compiler, Language};
+use crate::channel::{self, GitInfo};
 pub use crate::flags::Subcommand;
 use crate::flags::{Color, Flags};
-use crate::util::{exe, output, program_out_of_date, t};
+use crate::util::{exe, output, t};
 use once_cell::sync::OnceCell;
 use serde::{Deserialize, Deserializer};
 
@@ -33,6 +33,17 @@ macro_rules! check_ci_llvm {
     };
 }
 
+#[derive(Clone, Default)]
+pub enum DryRun {
+    /// This isn't a dry run.
+    #[default]
+    Disabled,
+    /// This is a dry run enabled by bootstrap itself, so it can verify that no work is done.
+    SelfCheck,
+    /// This is a dry run enabled by the `--dry-run` flag.
+    UserSelected,
+}
+
 /// Global configuration for the entire build and/or bootstrap.
 ///
 /// This structure is derived from a combination of both `config.toml` and
@@ -73,8 +84,6 @@ pub struct Config {
     pub color: Color,
     pub patch_binaries_for_nix: bool,
     pub stage0_metadata: Stage0Metadata,
-    /// Whether to use the `c` feature of the `compiler_builtins` crate.
-    pub optimized_compiler_builtins: bool,
 
     pub on_fail: Option<String>,
     pub stage: u32,
@@ -82,11 +91,11 @@ pub struct Config {
     pub keep_stage_std: Vec<u32>,
     pub src: PathBuf,
     /// defaults to `config.toml`
-    pub config: PathBuf,
+    pub config: Option<PathBuf>,
     pub jobs: Option<u32>,
     pub cmd: Subcommand,
     pub incremental: bool,
-    pub dry_run: bool,
+    pub dry_run: DryRun,
     /// `None` if we shouldn't download CI compiler artifacts, or the commit to download if we should.
     #[cfg(not(test))]
     download_rustc_commit: Option<String>,
@@ -204,6 +213,7 @@ pub struct Config {
     pub npm: Option<PathBuf>,
     pub gdb: Option<PathBuf>,
     pub python: Option<PathBuf>,
+    pub reuse: Option<PathBuf>,
     pub cargo_native_static: bool,
     pub configure_args: Vec<String>,
 
@@ -215,6 +225,7 @@ pub struct Config {
     #[cfg(test)]
     pub initial_rustfmt: RefCell<RustfmtState>,
     pub out: PathBuf,
+    pub rust_info: channel::GitInfo,
 }
 
 #[derive(Default, Deserialize)]
@@ -601,6 +612,7 @@ define_config! {
         nodejs: Option<String> = "nodejs",
         npm: Option<String> = "npm",
         python: Option<String> = "python",
+        reuse: Option<String> = "reuse",
         locked_deps: Option<bool> = "locked-deps",
         vendor: Option<bool> = "vendor",
         full_bootstrap: Option<bool> = "full-bootstrap",
@@ -624,7 +636,6 @@ define_config! {
         bench_stage: Option<u32> = "bench-stage",
         patch_binaries_for_nix: Option<bool> = "patch-binaries-for-nix",
         metrics: Option<bool> = "metrics",
-        optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
     }
 }
 
@@ -784,7 +795,7 @@ impl Config {
         config.llvm_optimize = true;
         config.ninja_in_file = true;
         config.llvm_version_check = true;
-        config.llvm_static_stdcpp = true;
+        config.llvm_static_stdcpp = false;
         config.backtrace = true;
         config.rust_optimize = true;
         config.rust_optimize_tests = true;
@@ -823,7 +834,7 @@ impl Config {
         config.jobs = flags.jobs.map(threads_from_config);
         config.cmd = flags.cmd;
         config.incremental = flags.incremental;
-        config.dry_run = flags.dry_run;
+        config.dry_run = if flags.dry_run { DryRun::UserSelected } else { DryRun::Disabled };
         config.keep_stage = flags.keep_stage;
         config.keep_stage_std = flags.keep_stage_std;
         config.color = flags.color;
@@ -929,8 +940,10 @@ impl Config {
         // Give a hard error if `--config` or `RUST_BOOTSTRAP_CONFIG` are set to a missing path,
         // but not if `config.toml` hasn't been created.
         let mut toml = if !using_default_path || toml_path.exists() {
+            config.config = Some(toml_path.clone());
             get_toml(&toml_path)
         } else {
+            config.config = None;
             TomlConfig::default()
         };
 
@@ -945,7 +958,6 @@ impl Config {
         }
 
         config.changelog_seen = toml.changelog_seen;
-        config.config = toml_path;
 
         let build = toml.build.unwrap_or_default();
 
@@ -967,7 +979,7 @@ impl Config {
             .unwrap_or_else(|| config.out.join(config.build.triple).join("stage0/bin/cargo"));
 
         // NOTE: it's important this comes *after* we set `initial_rustc` just above.
-        if config.dry_run {
+        if config.dry_run() {
             let dir = config.out.join("tmp-dry-run");
             t!(fs::create_dir_all(&dir));
             config.out = dir;
@@ -994,6 +1006,7 @@ impl Config {
         config.npm = build.npm.map(PathBuf::from);
         config.gdb = build.gdb.map(PathBuf::from);
         config.python = build.python.map(PathBuf::from);
+        config.reuse = build.reuse.map(PathBuf::from);
         config.submodules = build.submodules;
         set(&mut config.low_priority, build.low_priority);
         set(&mut config.compiler_docs, build.compiler_docs);
@@ -1013,7 +1026,6 @@ impl Config {
         set(&mut config.print_step_timings, build.print_step_timings);
         set(&mut config.print_step_rusage, build.print_step_rusage);
         set(&mut config.patch_binaries_for_nix, build.patch_binaries_for_nix);
-        set(&mut config.optimized_compiler_builtins, build.optimized_compiler_builtins);
 
         config.verbose = cmp::max(config.verbose, flags.verbose);
 
@@ -1196,7 +1208,7 @@ impl Config {
             config.rust_codegen_units_std = rust.codegen_units_std.map(threads_from_config);
             config.rust_profile_use = flags.rust_profile_use.or(rust.profile_use);
             config.rust_profile_generate = flags.rust_profile_generate.or(rust.profile_generate);
-            config.download_rustc_commit = download_ci_rustc_commit(&config, rust.download_rustc);
+            config.download_rustc_commit = config.download_ci_rustc_commit(rust.download_rustc);
 
             config.rust_lto = rust
                 .lto
@@ -1229,8 +1241,12 @@ impl Config {
                 if let Some(s) = cfg.no_std {
                     target.no_std = s;
                 }
-                target.cc = cfg.cc.map(PathBuf::from);
-                target.cxx = cfg.cxx.map(PathBuf::from);
+                target.cc = cfg.cc.map(PathBuf::from).or_else(|| {
+                    target.ndk.as_ref().map(|ndk| ndk_compiler(Language::C, &triple, ndk))
+                });
+                target.cxx = cfg.cxx.map(PathBuf::from).or_else(|| {
+                    target.ndk.as_ref().map(|ndk| ndk_compiler(Language::CPlusPlus, &triple, ndk))
+                });
                 target.ar = cfg.ar.map(PathBuf::from);
                 target.ranlib = cfg.ranlib.map(PathBuf::from);
                 target.linker = cfg.linker.map(PathBuf::from);
@@ -1318,6 +1334,7 @@ impl Config {
 
         let default = config.channel == "dev";
         config.ignore_git = ignore_git.unwrap_or(default);
+        config.rust_info = GitInfo::new(config.ignore_git, &config.src);
 
         let download_rustc = config.download_rustc_commit.is_some();
         // See https://github.com/rust-lang/compiler-team/issues/326
@@ -1375,6 +1392,13 @@ impl Config {
         config
     }
 
+    pub(crate) fn dry_run(&self) -> bool {
+        match self.dry_run {
+            DryRun::Disabled => false,
+            DryRun::SelfCheck | DryRun::UserSelected => true,
+        }
+    }
+
     /// A git invocation which runs inside the source directory.
     ///
     /// Use this rather than `Command::new("git")` in order to support out-of-tree builds.
@@ -1384,21 +1408,46 @@ impl Config {
         git
     }
 
-    pub(crate) fn artifact_channel(&self, builder: &Builder<'_>, commit: &str) -> String {
-        if builder.rust_info.is_managed_git_subrepository() {
+    /// Bootstrap embeds a version number into the name of shared libraries it uploads in CI.
+    /// Return the version it would have used for the given commit.
+    pub(crate) fn artifact_version_part(&self, commit: &str) -> String {
+        let (channel, version) = if self.rust_info.is_managed_git_subrepository() {
             let mut channel = self.git();
             channel.arg("show").arg(format!("{}:src/ci/channel", commit));
             let channel = output(&mut channel);
-            channel.trim().to_owned()
-        } else if let Ok(channel) = fs::read_to_string(builder.src.join("src/ci/channel")) {
-            channel.trim().to_owned()
+            let mut version = self.git();
+            version.arg("show").arg(format!("{}:src/version", commit));
+            let version = output(&mut version);
+            (channel.trim().to_owned(), version.trim().to_owned())
         } else {
-            let src = builder.src.display();
-            eprintln!("error: failed to determine artifact channel");
-            eprintln!(
-                "help: either use git or ensure that {src}/src/ci/channel contains the name of the channel to use"
-            );
-            panic!();
+            let channel = fs::read_to_string(self.src.join("src/ci/channel"));
+            let version = fs::read_to_string(self.src.join("src/version"));
+            match (channel, version) {
+                (Ok(channel), Ok(version)) => {
+                    (channel.trim().to_owned(), version.trim().to_owned())
+                }
+                (channel, version) => {
+                    let src = self.src.display();
+                    eprintln!("error: failed to determine artifact channel and/or version");
+                    eprintln!(
+                        "help: consider using a git checkout or ensure these files are readable"
+                    );
+                    if let Err(channel) = channel {
+                        eprintln!("reading {}/src/ci/channel failed: {:?}", src, channel);
+                    }
+                    if let Err(version) = version {
+                        eprintln!("reading {}/src/version failed: {:?}", src, version);
+                    }
+                    panic!();
+                }
+            }
+        };
+
+        match channel.as_str() {
+            "stable" => version,
+            "beta" => channel,
+            "nightly" => channel,
+            other => unreachable!("{:?} is not recognized as a valid channel", other),
         }
     }
 
@@ -1437,17 +1486,17 @@ impl Config {
     ///
     /// If `false`, llvm should be linked statically.
     /// This is computed on demand since LLVM might have to first be downloaded from CI.
-    pub(crate) fn llvm_link_shared(builder: &Builder<'_>) -> bool {
-        let mut opt = builder.config.llvm_link_shared.get();
-        if opt.is_none() && builder.config.dry_run {
+    pub(crate) fn llvm_link_shared(&self) -> bool {
+        let mut opt = self.llvm_link_shared.get();
+        if opt.is_none() && self.dry_run() {
             // just assume static for now - dynamic linking isn't supported on all platforms
             return false;
         }
 
         let llvm_link_shared = *opt.get_or_insert_with(|| {
-            if builder.config.llvm_from_ci {
-                crate::native::maybe_download_ci_llvm(builder);
-                let ci_llvm = builder.config.ci_llvm_root();
+            if self.llvm_from_ci {
+                self.maybe_download_ci_llvm();
+                let ci_llvm = self.ci_llvm_root();
                 let link_type = t!(
                     std::fs::read_to_string(ci_llvm.join("link-type.txt")),
                     format!("CI llvm missing: {}", ci_llvm.display())
@@ -1459,36 +1508,42 @@ impl Config {
                 false
             }
         });
-        builder.config.llvm_link_shared.set(opt);
+        self.llvm_link_shared.set(opt);
         llvm_link_shared
     }
 
     /// Return whether we will use a downloaded, pre-compiled version of rustc, or just build from source.
-    pub(crate) fn download_rustc(builder: &Builder<'_>) -> bool {
-        static DOWNLOAD_RUSTC: OnceCell<bool> = OnceCell::new();
-        if builder.config.dry_run && DOWNLOAD_RUSTC.get().is_none() {
+    pub(crate) fn download_rustc(&self) -> bool {
+        self.download_rustc_commit().is_some()
+    }
+
+    pub(crate) fn download_rustc_commit(&self) -> Option<&'static str> {
+        static DOWNLOAD_RUSTC: OnceCell<Option<String>> = OnceCell::new();
+        if self.dry_run() && DOWNLOAD_RUSTC.get().is_none() {
             // avoid trying to actually download the commit
-            return false;
+            return None;
         }
 
-        *DOWNLOAD_RUSTC.get_or_init(|| match &builder.config.download_rustc_commit {
-            None => false,
-            Some(commit) => {
-                download_ci_rustc(builder, commit);
-                true
-            }
-        })
+        DOWNLOAD_RUSTC
+            .get_or_init(|| match &self.download_rustc_commit {
+                None => None,
+                Some(commit) => {
+                    self.download_ci_rustc(commit);
+                    Some(commit.clone())
+                }
+            })
+            .as_deref()
     }
 
-    pub(crate) fn initial_rustfmt(builder: &Builder<'_>) -> Option<PathBuf> {
-        match &mut *builder.config.initial_rustfmt.borrow_mut() {
+    pub(crate) fn initial_rustfmt(&self) -> Option<PathBuf> {
+        match &mut *self.initial_rustfmt.borrow_mut() {
             RustfmtState::SystemToolchain(p) | RustfmtState::Downloaded(p) => Some(p.clone()),
             RustfmtState::Unavailable => None,
             r @ RustfmtState::LazyEvaluated => {
-                if builder.config.dry_run {
+                if self.dry_run() {
                     return Some(PathBuf::new());
                 }
-                let path = maybe_download_rustfmt(builder);
+                let path = self.maybe_download_rustfmt();
                 *r = if let Some(p) = &path {
                     RustfmtState::Downloaded(p.clone())
                 } else {
@@ -1499,8 +1554,10 @@ impl Config {
         }
     }
 
-    pub fn verbose(&self) -> bool {
-        self.verbose > 0
+    pub fn verbose(&self, msg: &str) {
+        if self.verbose > 0 {
+            println!("{}", msg);
+        }
     }
 
     pub fn sanitizers_enabled(&self, target: TargetSelection) -> bool {
@@ -1538,218 +1595,77 @@ impl Config {
     pub fn submodules(&self, rust_info: &GitInfo) -> bool {
         self.submodules.unwrap_or(rust_info.is_managed_git_subrepository())
     }
-}
 
-fn set<T>(field: &mut T, val: Option<T>) {
-    if let Some(v) = val {
-        *field = v;
-    }
-}
-
-fn threads_from_config(v: u32) -> u32 {
-    match v {
-        0 => std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get) as u32,
-        n => n,
-    }
-}
+    /// Returns the commit to download, or `None` if we shouldn't download CI artifacts.
+    fn download_ci_rustc_commit(&self, download_rustc: Option<StringOrBool>) -> Option<String> {
+        // If `download-rustc` is not set, default to rebuilding.
+        let if_unchanged = match download_rustc {
+            None | Some(StringOrBool::Bool(false)) => return None,
+            Some(StringOrBool::Bool(true)) => false,
+            Some(StringOrBool::String(s)) if s == "if-unchanged" => true,
+            Some(StringOrBool::String(other)) => {
+                panic!("unrecognized option for download-rustc: {}", other)
+            }
+        };
 
-/// Returns the commit to download, or `None` if we shouldn't download CI artifacts.
-fn download_ci_rustc_commit(
-    config: &Config,
-    download_rustc: Option<StringOrBool>,
-) -> Option<String> {
-    // If `download-rustc` is not set, default to rebuilding.
-    let if_unchanged = match download_rustc {
-        None | Some(StringOrBool::Bool(false)) => return None,
-        Some(StringOrBool::Bool(true)) => false,
-        Some(StringOrBool::String(s)) if s == "if-unchanged" => true,
-        Some(StringOrBool::String(other)) => {
-            panic!("unrecognized option for download-rustc: {}", other)
+        // Handle running from a directory other than the top level
+        let top_level = output(self.git().args(&["rev-parse", "--show-toplevel"]));
+        let top_level = top_level.trim_end();
+        let compiler = format!("{top_level}/compiler/");
+        let library = format!("{top_level}/library/");
+
+        // Look for a version to compare to based on the current commit.
+        // Only commits merged by bors will have CI artifacts.
+        let merge_base = output(
+            self.git()
+                .arg("rev-list")
+                .arg(format!("--author={}", self.stage0_metadata.config.git_merge_commit_email))
+                .args(&["-n1", "--first-parent", "HEAD"]),
+        );
+        let commit = merge_base.trim_end();
+        if commit.is_empty() {
+            println!("error: could not find commit hash for downloading rustc");
+            println!("help: maybe your repository history is too shallow?");
+            println!("help: consider disabling `download-rustc`");
+            println!("help: or fetch enough history to include one upstream commit");
+            crate::detail_exit(1);
         }
-    };
 
-    // Handle running from a directory other than the top level
-    let top_level = output(config.git().args(&["rev-parse", "--show-toplevel"]));
-    let top_level = top_level.trim_end();
-    let compiler = format!("{top_level}/compiler/");
-    let library = format!("{top_level}/library/");
-
-    // Look for a version to compare to based on the current commit.
-    // Only commits merged by bors will have CI artifacts.
-    let merge_base = output(
-        config
+        // Warn if there were changes to the compiler or standard library since the ancestor commit.
+        let has_changes = !t!(self
             .git()
-            .arg("rev-list")
-            .arg(format!("--author={}", config.stage0_metadata.config.git_merge_commit_email))
-            .args(&["-n1", "--first-parent", "HEAD"]),
-    );
-    let commit = merge_base.trim_end();
-    if commit.is_empty() {
-        println!("error: could not find commit hash for downloading rustc");
-        println!("help: maybe your repository history is too shallow?");
-        println!("help: consider disabling `download-rustc`");
-        println!("help: or fetch enough history to include one upstream commit");
-        crate::detail_exit(1);
-    }
-
-    // Warn if there were changes to the compiler or standard library since the ancestor commit.
-    let has_changes = !t!(config
-        .git()
-        .args(&["diff-index", "--quiet", &commit, "--", &compiler, &library])
-        .status())
-    .success();
-    if has_changes {
-        if if_unchanged {
-            if config.verbose > 0 {
-                println!(
-                    "warning: saw changes to compiler/ or library/ since {commit}; \
-                          ignoring `download-rustc`"
-                );
+            .args(&["diff-index", "--quiet", &commit, "--", &compiler, &library])
+            .status())
+        .success();
+        if has_changes {
+            if if_unchanged {
+                if self.verbose > 0 {
+                    println!(
+                        "warning: saw changes to compiler/ or library/ since {commit}; \
+                            ignoring `download-rustc`"
+                    );
+                }
+                return None;
             }
-            return None;
+            println!(
+                "warning: `download-rustc` is enabled, but there are changes to \
+                    compiler/ or library/"
+            );
         }
-        println!(
-            "warning: `download-rustc` is enabled, but there are changes to \
-                  compiler/ or library/"
-        );
-    }
-
-    Some(commit.to_string())
-}
 
-fn maybe_download_rustfmt(builder: &Builder<'_>) -> Option<PathBuf> {
-    let RustfmtMetadata { date, version } = builder.config.stage0_metadata.rustfmt.as_ref()?;
-    let channel = format!("{version}-{date}");
-
-    let host = builder.config.build;
-    let rustfmt_path = builder.config.initial_rustc.with_file_name(exe("rustfmt", host));
-    let bin_root = builder.config.out.join(host.triple).join("stage0");
-    let rustfmt_stamp = bin_root.join(".rustfmt-stamp");
-    if rustfmt_path.exists() && !program_out_of_date(&rustfmt_stamp, &channel) {
-        return Some(rustfmt_path);
+        Some(commit.to_string())
     }
-
-    let filename = format!("rustfmt-{version}-{build}.tar.xz", build = host.triple);
-    download_component(builder, DownloadSource::Dist, filename, "rustfmt-preview", &date, "stage0");
-
-    builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustfmt"));
-    builder.fix_bin_or_dylib(&bin_root.join("bin").join("cargo-fmt"));
-
-    builder.create(&rustfmt_stamp, &channel);
-    Some(rustfmt_path)
 }
 
-fn download_ci_rustc(builder: &Builder<'_>, commit: &str) {
-    builder.verbose(&format!("using downloaded stage2 artifacts from CI (commit {commit})"));
-    let channel = builder.config.artifact_channel(builder, commit);
-    let host = builder.config.build.triple;
-    let bin_root = builder.out.join(host).join("ci-rustc");
-    let rustc_stamp = bin_root.join(".rustc-stamp");
-
-    if !bin_root.join("bin").join("rustc").exists() || program_out_of_date(&rustc_stamp, commit) {
-        if bin_root.exists() {
-            t!(fs::remove_dir_all(&bin_root));
-        }
-        let filename = format!("rust-std-{channel}-{host}.tar.xz");
-        let pattern = format!("rust-std-{host}");
-        download_ci_component(builder, filename, &pattern, commit);
-        let filename = format!("rustc-{channel}-{host}.tar.xz");
-        download_ci_component(builder, filename, "rustc", commit);
-        // download-rustc doesn't need its own cargo, it can just use beta's.
-        let filename = format!("rustc-dev-{channel}-{host}.tar.xz");
-        download_ci_component(builder, filename, "rustc-dev", commit);
-
-        builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustc"));
-        builder.fix_bin_or_dylib(&bin_root.join("bin").join("rustdoc"));
-        let lib_dir = bin_root.join("lib");
-        for lib in t!(fs::read_dir(&lib_dir), lib_dir.display().to_string()) {
-            let lib = t!(lib);
-            if lib.path().extension() == Some(OsStr::new("so")) {
-                builder.fix_bin_or_dylib(&lib.path());
-            }
-        }
-        t!(fs::write(rustc_stamp, commit));
+fn set<T>(field: &mut T, val: Option<T>) {
+    if let Some(v) = val {
+        *field = v;
     }
 }
 
-pub(crate) enum DownloadSource {
-    CI,
-    Dist,
-}
-
-/// Download a single component of a CI-built toolchain (not necessarily a published nightly).
-// NOTE: intentionally takes an owned string to avoid downloading multiple times by accident
-fn download_ci_component(builder: &Builder<'_>, filename: String, prefix: &str, commit: &str) {
-    download_component(builder, DownloadSource::CI, filename, prefix, commit, "ci-rustc")
-}
-
-fn download_component(
-    builder: &Builder<'_>,
-    mode: DownloadSource,
-    filename: String,
-    prefix: &str,
-    key: &str,
-    destination: &str,
-) {
-    let cache_dst = builder.out.join("cache");
-    let cache_dir = cache_dst.join(key);
-    if !cache_dir.exists() {
-        t!(fs::create_dir_all(&cache_dir));
-    }
-
-    let bin_root = builder.out.join(builder.config.build.triple).join(destination);
-    let tarball = cache_dir.join(&filename);
-    let (base_url, url, should_verify) = match mode {
-        DownloadSource::CI => (
-            builder.config.stage0_metadata.config.artifacts_server.clone(),
-            format!("{key}/{filename}"),
-            false,
-        ),
-        DownloadSource::Dist => {
-            let dist_server = env::var("RUSTUP_DIST_SERVER")
-                .unwrap_or(builder.config.stage0_metadata.config.dist_server.to_string());
-            // NOTE: make `dist` part of the URL because that's how it's stored in src/stage0.json
-            (dist_server, format!("dist/{key}/{filename}"), true)
-        }
-    };
-
-    // For the beta compiler, put special effort into ensuring the checksums are valid.
-    // FIXME: maybe we should do this for download-rustc as well? but it would be a pain to update
-    // this on each and every nightly ...
-    let checksum = if should_verify {
-        let error = format!(
-            "src/stage0.json doesn't contain a checksum for {url}. \
-            Pre-built artifacts might not be available for this \
-            target at this time, see https://doc.rust-lang.org/nightly\
-            /rustc/platform-support.html for more information."
-        );
-        let sha256 = builder.config.stage0_metadata.checksums_sha256.get(&url).expect(&error);
-        if tarball.exists() {
-            if builder.verify(&tarball, sha256) {
-                builder.unpack(&tarball, &bin_root, prefix);
-                return;
-            } else {
-                builder.verbose(&format!(
-                    "ignoring cached file {} due to failed verification",
-                    tarball.display()
-                ));
-                builder.remove(&tarball);
-            }
-        }
-        Some(sha256)
-    } else if tarball.exists() {
-        builder.unpack(&tarball, &bin_root, prefix);
-        return;
-    } else {
-        None
-    };
-
-    builder.download_component(&format!("{base_url}/{url}"), &tarball, "");
-    if let Some(sha256) = checksum {
-        if !builder.verify(&tarball, sha256) {
-            panic!("failed to verify {}", tarball.display());
-        }
+fn threads_from_config(v: u32) -> u32 {
+    match v {
+        0 => std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get) as u32,
+        n => n,
     }
-
-    builder.unpack(&tarball, &bin_root, prefix);
 }
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 12585e80e..3cb0eccd3 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -10,15 +10,20 @@
 
 use std::collections::HashSet;
 use std::env;
+use std::ffi::OsStr;
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
+use object::read::archive::ArchiveFile;
+use object::BinaryFormat;
+
 use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::{Interned, INTERNER};
 use crate::channel;
 use crate::compile;
 use crate::config::TargetSelection;
+use crate::doc::DocumentationFormat;
 use crate::tarball::{GeneratedTarball, OverlayKind, Tarball};
 use crate::tool::{self, Tool};
 use crate::util::{exe, is_dylib, output, t, timeit};
@@ -97,7 +102,11 @@ impl Step for JsonDocs {
     /// Builds the `rust-docs-json` installer component.
     fn run(self, builder: &Builder<'_>) -> Option<GeneratedTarball> {
         let host = self.host;
-        builder.ensure(crate::doc::JsonStd { stage: builder.top_stage, target: host });
+        builder.ensure(crate::doc::Std {
+            stage: builder.top_stage,
+            target: host,
+            format: DocumentationFormat::JSON,
+        });
 
         let dest = "share/doc/rust/json";
 
@@ -550,6 +559,39 @@ fn skip_host_target_lib(builder: &Builder<'_>, compiler: Compiler) -> bool {
     }
 }
 
+/// Check that all objects in rlibs for UEFI targets are COFF. This
+/// ensures that the C compiler isn't producing ELF objects, which would
+/// not link correctly with the COFF objects.
+fn verify_uefi_rlib_format(builder: &Builder<'_>, target: TargetSelection, stamp: &Path) {
+    if !target.ends_with("-uefi") {
+        return;
+    }
+
+    for (path, _) in builder.read_stamp_file(stamp) {
+        if path.extension() != Some(OsStr::new("rlib")) {
+            continue;
+        }
+
+        let data = t!(fs::read(&path));
+        let data = data.as_slice();
+        let archive = t!(ArchiveFile::parse(data));
+        for member in archive.members() {
+            let member = t!(member);
+            let member_data = t!(member.data(data));
+
+            let is_coff = match object::File::parse(member_data) {
+                Ok(member_file) => member_file.format() == BinaryFormat::Coff,
+                Err(_) => false,
+            };
+
+            if !is_coff {
+                let member_name = String::from_utf8_lossy(member.name());
+                panic!("member {} in {} is not COFF", member_name, path.display());
+            }
+        }
+    }
+}
+
 /// Copy stamped files into an image's `target/lib` directory.
 fn copy_target_libs(builder: &Builder<'_>, target: TargetSelection, image: &Path, stamp: &Path) {
     let dst = image.join("lib/rustlib").join(target.triple).join("lib");
@@ -605,6 +647,7 @@ impl Step for Std {
 
         let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
         let stamp = compile::libstd_stamp(builder, compiler_to_use, target);
+        verify_uefi_rlib_format(builder, target, &stamp);
         copy_target_libs(builder, target, &tarball.image_dir(), &stamp);
 
         Some(tarball.generate())
@@ -919,13 +962,13 @@ impl Step for PlainSourceTarball {
 
         // Create the version file
         builder.create(&plain_dst_src.join("version"), &builder.rust_version());
-        if let Some(info) = builder.rust_info.info() {
+        if let Some(info) = builder.rust_info().info() {
             channel::write_commit_hash_file(&plain_dst_src, &info.sha);
             channel::write_commit_info_file(&plain_dst_src, info);
         }
 
         // If we're building from git sources, we need to vendor a complete distribution.
-        if builder.rust_info.is_managed_git_subrepository() {
+        if builder.rust_info().is_managed_git_subrepository() {
             // Ensure we have the submodules checked out.
             builder.update_submodule(Path::new("src/tools/rust-analyzer"));
 
@@ -940,7 +983,7 @@ impl Step for PlainSourceTarball {
                 .arg(builder.src.join("./src/bootstrap/Cargo.toml"))
                 .current_dir(&plain_dst_src);
 
-            let config = if !builder.config.dry_run {
+            let config = if !builder.config.dry_run() {
                 t!(String::from_utf8(t!(cmd.output()).stdout))
             } else {
                 String::new()
@@ -1381,7 +1424,7 @@ impl Step for Extended {
         let etc = builder.src.join("src/etc/installer");
 
         // Avoid producing tarballs during a dry run.
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return;
         }
 
@@ -1819,7 +1862,7 @@ impl Step for Extended {
             let _time = timeit(builder);
             builder.run(&mut cmd);
 
-            if !builder.config.dry_run {
+            if !builder.config.dry_run() {
                 t!(fs::rename(exe.join(&filename), distdir(builder).join(&filename)));
             }
         }
@@ -1853,21 +1896,23 @@ fn add_env(builder: &Builder<'_>, cmd: &mut Command, target: TargetSelection) {
 ///
 /// Returns whether the files were actually copied.
 fn maybe_install_llvm(builder: &Builder<'_>, target: TargetSelection, dst_libdir: &Path) -> bool {
-    if !builder.is_rust_llvm(target) {
-        // If the LLVM was externally provided, then we don't currently copy
-        // artifacts into the sysroot. This is not necessarily the right
-        // choice (in particular, it will require the LLVM dylib to be in
-        // the linker's load path at runtime), but the common use case for
-        // external LLVMs is distribution provided LLVMs, and in that case
-        // they're usually in the standard search path (e.g., /usr/lib) and
-        // copying them here is going to cause problems as we may end up
-        // with the wrong files and isn't what distributions want.
-        //
-        // This behavior may be revisited in the future though.
-        //
-        // If the LLVM is coming from ourselves (just from CI) though, we
-        // still want to install it, as it otherwise won't be available.
-        return false;
+    if let Some(config) = builder.config.target_config.get(&target) {
+        if config.llvm_config.is_some() && !builder.config.llvm_from_ci {
+            // If the LLVM was externally provided, then we don't currently copy
+            // artifacts into the sysroot. This is not necessarily the right
+            // choice (in particular, it will require the LLVM dylib to be in
+            // the linker's load path at runtime), but the common use case for
+            // external LLVMs is distribution provided LLVMs, and in that case
+            // they're usually in the standard search path (e.g., /usr/lib) and
+            // copying them here is going to cause problems as we may end up
+            // with the wrong files and isn't what distributions want.
+            //
+            // This behavior may be revisited in the future though.
+            //
+            // If the LLVM is coming from ourselves (just from CI) though, we
+            // still want to install it, as it otherwise won't be available.
+            return false;
+        }
     }
 
     // On macOS, rustc (and LLVM tools) link to an unversioned libLLVM.dylib
@@ -1881,12 +1926,12 @@ fn maybe_install_llvm(builder: &Builder<'_>, target: TargetSelection, dst_libdir
         if llvm_dylib_path.exists() {
             builder.install(&llvm_dylib_path, dst_libdir, 0o644);
         }
-        !builder.config.dry_run
+        !builder.config.dry_run()
     } else if let Ok(llvm_config) = crate::native::prebuilt_llvm_config(builder, target) {
         let mut cmd = Command::new(llvm_config);
         cmd.arg("--libfiles");
         builder.verbose(&format!("running {:?}", cmd));
-        let files = if builder.config.dry_run { "".into() } else { output(&mut cmd) };
+        let files = if builder.config.dry_run() { "".into() } else { output(&mut cmd) };
         let build_llvm_out = &builder.llvm_out(builder.config.build);
         let target_llvm_out = &builder.llvm_out(target);
         for file in files.trim_end().split(' ') {
@@ -1898,7 +1943,7 @@ fn maybe_install_llvm(builder: &Builder<'_>, target: TargetSelection, dst_libdir
             };
             builder.install(&file, dst_libdir, 0o644);
         }
-        !builder.config.dry_run
+        !builder.config.dry_run()
     } else {
         false
     }
diff --git a/src/bootstrap/doc.rs b/src/bootstrap/doc.rs
index ea06caf9c..2c6fd1e1d 100644
--- a/src/bootstrap/doc.rs
+++ b/src/bootstrap/doc.rs
@@ -85,18 +85,6 @@ book!(
     StyleGuide, "src/doc/style-guide", "style-guide";
 );
 
-fn open(builder: &Builder<'_>, path: impl AsRef<Path>) {
-    if builder.config.dry_run || !builder.config.cmd.open() {
-        return;
-    }
-
-    let path = path.as_ref();
-    builder.info(&format!("Opening doc {}", path.display()));
-    if let Err(err) = opener::open(path) {
-        builder.info(&format!("{}\n", err));
-    }
-}
-
 // "library/std" -> ["library", "std"]
 //
 // Used for deciding whether a particular step is one requested by the user on
@@ -163,7 +151,7 @@ impl Step for RustbookSrc {
         let index = out.join("index.html");
         let rustbook = builder.tool_exe(Tool::Rustbook);
         let mut rustbook_cmd = builder.tool_cmd(Tool::Rustbook);
-        if builder.config.dry_run || up_to_date(&src, &index) && up_to_date(&rustbook, &index) {
+        if builder.config.dry_run() || up_to_date(&src, &index) && up_to_date(&rustbook, &index) {
             return;
         }
         builder.info(&format!("Rustbook ({}) - {}", target, name));
@@ -240,11 +228,9 @@ impl Step for TheBook {
             invoke_rustdoc(builder, compiler, &shared_assets, target, path);
         }
 
-        if builder.was_invoked_explicitly::<Self>(Kind::Doc) {
-            let out = builder.doc_out(target);
-            let index = out.join("book").join("index.html");
-            open(builder, &index);
-        }
+        let out = builder.doc_out(target);
+        let index = out.join("book").join("index.html");
+        builder.maybe_open_in_browser::<Self>(index);
     }
 }
 
@@ -345,8 +331,8 @@ impl Step for Standalone {
                 && up_to_date(&footer, &html)
                 && up_to_date(&favicon, &html)
                 && up_to_date(&full_toc, &html)
-                && (builder.config.dry_run || up_to_date(&version_info, &html))
-                && (builder.config.dry_run || up_to_date(&rustdoc, &html))
+                && (builder.config.dry_run() || up_to_date(&version_info, &html))
+                && (builder.config.dry_run() || up_to_date(&rustdoc, &html))
             {
                 continue;
             }
@@ -386,7 +372,7 @@ impl Step for Standalone {
         // with no particular explicit doc requested (e.g. library/core).
         if builder.paths.is_empty() || builder.was_invoked_explicitly::<Self>(Kind::Doc) {
             let index = out.join("index.html");
-            open(builder, &index);
+            builder.open_in_browser(&index);
         }
     }
 }
@@ -416,11 +402,11 @@ impl Step for SharedAssets {
 
         let version_input = builder.src.join("src").join("doc").join("version_info.html.template");
         let version_info = out.join("version_info.html");
-        if !builder.config.dry_run && !up_to_date(&version_input, &version_info) {
+        if !builder.config.dry_run() && !up_to_date(&version_input, &version_info) {
             let info = t!(fs::read_to_string(&version_input))
                 .replace("VERSION", &builder.rust_release())
-                .replace("SHORT_HASH", builder.rust_info.sha_short().unwrap_or(""))
-                .replace("STAMP", builder.rust_info.sha().unwrap_or(""));
+                .replace("SHORT_HASH", builder.rust_info().sha_short().unwrap_or(""))
+                .replace("STAMP", builder.rust_info().sha().unwrap_or(""));
             t!(fs::write(&version_info, &info));
         }
 
@@ -434,6 +420,7 @@ impl Step for SharedAssets {
 pub struct Std {
     pub stage: u32,
     pub target: TargetSelection,
+    pub format: DocumentationFormat,
 }
 
 impl Step for Std {
@@ -446,7 +433,15 @@ impl Step for Std {
     }
 
     fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Std { stage: run.builder.top_stage, target: run.target });
+        run.builder.ensure(Std {
+            stage: run.builder.top_stage,
+            target: run.target,
+            format: if run.builder.config.cmd.json() {
+                DocumentationFormat::JSON
+            } else {
+                DocumentationFormat::HTML
+            },
+        });
     }
 
     /// Compile all standard library documentation.
@@ -456,19 +451,28 @@ impl Step for Std {
     fn run(self, builder: &Builder<'_>) {
         let stage = self.stage;
         let target = self.target;
-        let out = builder.doc_out(target);
+        let out = match self.format {
+            DocumentationFormat::HTML => builder.doc_out(target),
+            DocumentationFormat::JSON => builder.json_doc_out(target),
+        };
+
         t!(fs::create_dir_all(&out));
 
-        builder.ensure(SharedAssets { target: self.target });
+        if self.format == DocumentationFormat::HTML {
+            builder.ensure(SharedAssets { target: self.target });
+        }
 
         let index_page = builder.src.join("src/doc/index.md").into_os_string();
-        let mut extra_args = vec![
-            OsStr::new("--markdown-css"),
-            OsStr::new("rust.css"),
-            OsStr::new("--markdown-no-toc"),
-            OsStr::new("--index-page"),
-            &index_page,
-        ];
+        let mut extra_args = match self.format {
+            DocumentationFormat::HTML => vec![
+                OsStr::new("--markdown-css"),
+                OsStr::new("rust.css"),
+                OsStr::new("--markdown-no-toc"),
+                OsStr::new("--index-page"),
+                &index_page,
+            ],
+            DocumentationFormat::JSON => vec![OsStr::new("--output-format"), OsStr::new("json")],
+        };
 
         if !builder.config.docs_minification {
             extra_args.push(OsStr::new("--disable-minification"));
@@ -492,59 +496,24 @@ impl Step for Std {
             })
             .collect::<Vec<_>>();
 
-        doc_std(
-            builder,
-            DocumentationFormat::HTML,
-            stage,
-            target,
-            &out,
-            &extra_args,
-            &requested_crates,
-        );
+        doc_std(builder, self.format, stage, target, &out, &extra_args, &requested_crates);
+
+        // Don't open if the format is json
+        if let DocumentationFormat::JSON = self.format {
+            return;
+        }
 
         // Look for library/std, library/core etc in the `x.py doc` arguments and
         // open the corresponding rendered docs.
         for requested_crate in requested_crates {
             if STD_PUBLIC_CRATES.iter().any(|k| *k == requested_crate.as_str()) {
                 let index = out.join(requested_crate).join("index.html");
-                open(builder, &index);
+                builder.open_in_browser(index);
             }
         }
     }
 }
 
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
-pub struct JsonStd {
-    pub stage: u32,
-    pub target: TargetSelection,
-}
-
-impl Step for JsonStd {
-    type Output = ();
-    const DEFAULT: bool = false;
-
-    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        let default = run.builder.config.docs && run.builder.config.cmd.json();
-        run.all_krates("test").path("library").default_condition(default)
-    }
-
-    fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Std { stage: run.builder.top_stage, target: run.target });
-    }
-
-    /// Build JSON documentation for the standard library crates.
-    ///
-    /// This is largely just a wrapper around `cargo doc`.
-    fn run(self, builder: &Builder<'_>) {
-        let stage = self.stage;
-        let target = self.target;
-        let out = builder.json_doc_out(target);
-        t!(fs::create_dir_all(&out));
-        let extra_args = [OsStr::new("--output-format"), OsStr::new("json")];
-        doc_std(builder, DocumentationFormat::JSON, stage, target, &out, &extra_args, &[])
-    }
-}
-
 /// Name of the crates that are visible to consumers of the standard library.
 /// Documentation for internal crates is handled by the rustc step, so internal crates will show
 /// up there.
@@ -557,7 +526,7 @@ impl Step for JsonStd {
 const STD_PUBLIC_CRATES: [&str; 5] = ["core", "alloc", "std", "proc_macro", "test"];
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
-enum DocumentationFormat {
+pub enum DocumentationFormat {
     HTML,
     JSON,
 }
@@ -597,27 +566,22 @@ fn doc_std(
         );
     }
     let compiler = builder.compiler(stage, builder.config.build);
+
+    let target_doc_dir_name = if format == DocumentationFormat::JSON { "json-doc" } else { "doc" };
+    let target_dir =
+        builder.stage_out(compiler, Mode::Std).join(target.triple).join(target_doc_dir_name);
+
     // This is directory where the compiler will place the output of the command.
     // We will then copy the files from this directory into the final `out` directory, the specified
     // as a function parameter.
-    let out_dir = builder.stage_out(compiler, Mode::Std).join(target.triple).join("doc");
-    // `cargo` uses the same directory for both JSON docs and HTML docs.
-    // This could lead to cross-contamination when copying files into the specified `out` directory.
-    // For example:
-    // ```bash
-    // x doc std
-    // x doc std --json
-    // ```
-    // could lead to HTML docs being copied into the JSON docs output directory.
-    // To avoid this issue, we clean the doc folder before invoking `cargo`.
-    if out_dir.exists() {
-        builder.remove_dir(&out_dir);
-    }
+    let out_dir = target_dir.join(target.triple).join("doc");
 
     let run_cargo_rustdoc_for = |package: &str| {
         let mut cargo = builder.cargo(compiler, Mode::Std, SourceType::InTree, target, "rustdoc");
         compile::std_cargo(builder, target, compiler.stage, &mut cargo);
         cargo
+            .arg("--target-dir")
+            .arg(&*target_dir.to_string_lossy())
             .arg("-p")
             .arg(package)
             .arg("-Zskip-rustdoc-fingerprint")
@@ -759,13 +723,13 @@ impl Step for Rustc {
         // Let's open the first crate documentation page:
         if let Some(krate) = to_open {
             let index = out.join(krate).join("index.html");
-            open(builder, &index);
+            builder.open_in_browser(index);
         }
     }
 }
 
 macro_rules! tool_doc {
-    ($tool: ident, $should_run: literal, $path: literal, [$($krate: literal),+ $(,)?], in_tree = $in_tree:expr $(,)?) => {
+    ($tool: ident, $should_run: literal, $path: literal, [$($krate: literal),+ $(,)?] $(,)?) => {
         #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
         pub struct $tool {
             target: TargetSelection,
@@ -821,12 +785,6 @@ macro_rules! tool_doc {
                 t!(fs::create_dir_all(&out_dir));
                 t!(symlink_dir_force(&builder.config, &out, &out_dir));
 
-                let source_type = if $in_tree == true {
-                    SourceType::InTree
-                } else {
-                    SourceType::Submodule
-                };
-
                 // Build cargo command.
                 let mut cargo = prepare_tool_cargo(
                     builder,
@@ -835,7 +793,7 @@ macro_rules! tool_doc {
                     target,
                     "doc",
                     $path,
-                    source_type,
+                    SourceType::InTree,
                     &[],
                 );
 
@@ -851,38 +809,21 @@ macro_rules! tool_doc {
                 cargo.rustdocflag("--show-type-layout");
                 cargo.rustdocflag("--generate-link-to-definition");
                 cargo.rustdocflag("-Zunstable-options");
-                if $in_tree == true {
-                    builder.run(&mut cargo.into());
-                } else {
-                    // Allow out-of-tree docs to fail (since the tool might be in a broken state).
-                    if !builder.try_run(&mut cargo.into()) {
-                        builder.info(&format!(
-                            "WARNING: tool {} failed to document; ignoring failure because it is an out-of-tree tool",
-                            stringify!($tool).to_lowercase(),
-                        ));
-                    }
-                }
+                builder.run(&mut cargo.into());
             }
         }
     }
 }
 
-tool_doc!(
-    Rustdoc,
-    "rustdoc-tool",
-    "src/tools/rustdoc",
-    ["rustdoc", "rustdoc-json-types"],
-    in_tree = true
-);
+tool_doc!(Rustdoc, "rustdoc-tool", "src/tools/rustdoc", ["rustdoc", "rustdoc-json-types"],);
 tool_doc!(
     Rustfmt,
     "rustfmt-nightly",
     "src/tools/rustfmt",
     ["rustfmt-nightly", "rustfmt-config_proc_macro"],
-    in_tree = true
 );
-tool_doc!(Clippy, "clippy", "src/tools/clippy", ["clippy_utils"], in_tree = true);
-tool_doc!(Miri, "miri", "src/tools/miri", ["miri"], in_tree = false);
+tool_doc!(Clippy, "clippy", "src/tools/clippy", ["clippy_utils"]);
+tool_doc!(Miri, "miri", "src/tools/miri", ["miri"]);
 
 #[derive(Ord, PartialOrd, Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct ErrorIndex {
@@ -956,7 +897,7 @@ impl Step for UnstableBookGen {
 }
 
 fn symlink_dir_force(config: &Config, src: &Path, dst: &Path) -> io::Result<()> {
-    if config.dry_run {
+    if config.dry_run() {
         return Ok(());
     }
     if let Ok(m) = fs::symlink_metadata(dst) {
@@ -1021,7 +962,7 @@ impl Step for RustcBook {
         cmd.arg("--rustc");
         cmd.arg(&rustc);
         cmd.arg("--rustc-target").arg(&self.target.rustc_target_arg());
-        if builder.config.verbose() {
+        if builder.is_verbose() {
             cmd.arg("--verbose");
         }
         if self.validate {
@@ -1042,10 +983,9 @@ impl Step for RustcBook {
             name: INTERNER.intern_str("rustc"),
             src: INTERNER.intern_path(out_base),
         });
-        if builder.was_invoked_explicitly::<Self>(Kind::Doc) {
-            let out = builder.doc_out(self.target);
-            let index = out.join("rustc").join("index.html");
-            open(builder, &index);
-        }
+
+        let out = builder.doc_out(self.target);
+        let index = out.join("rustc").join("index.html");
+        builder.maybe_open_in_browser::<Self>(index);
     }
 }
diff --git a/src/bootstrap/download.rs b/src/bootstrap/download.rs
new file mode 100644
index 000000000..6ae283f32
--- /dev/null
+++ b/src/bootstrap/download.rs
@@ -0,0 +1,520 @@
+use std::{
+    env,
+    ffi::{OsStr, OsString},
+    fs::{self, File},
+    io::{BufRead, BufReader, ErrorKind},
+    path::{Path, PathBuf},
+    process::{Command, Stdio},
+};
+
+use once_cell::sync::OnceCell;
+use xz2::bufread::XzDecoder;
+
+use crate::{
+    config::RustfmtMetadata,
+    native::detect_llvm_sha,
+    t,
+    util::{check_run, exe, program_out_of_date, try_run},
+    Config,
+};
+
+/// Generic helpers that are useful anywhere in bootstrap.
+impl Config {
+    pub fn is_verbose(&self) -> bool {
+        self.verbose > 0
+    }
+
+    pub(crate) fn create(&self, path: &Path, s: &str) {
+        if self.dry_run() {
+            return;
+        }
+        t!(fs::write(path, s));
+    }
+
+    pub(crate) fn remove(&self, f: &Path) {
+        if self.dry_run() {
+            return;
+        }
+        fs::remove_file(f).unwrap_or_else(|_| panic!("failed to remove {:?}", f));
+    }
+
+    /// Create a temporary directory in `out` and return its path.
+    ///
+    /// NOTE: this temporary directory is shared between all steps;
+    /// if you need an empty directory, create a new subdirectory inside it.
+    pub(crate) fn tempdir(&self) -> PathBuf {
+        let tmp = self.out.join("tmp");
+        t!(fs::create_dir_all(&tmp));
+        tmp
+    }
+
+    /// Runs a command, printing out nice contextual information if it fails.
+    /// Exits if the command failed to execute at all, otherwise returns its
+    /// `status.success()`.
+    pub(crate) fn try_run(&self, cmd: &mut Command) -> bool {
+        if self.dry_run() {
+            return true;
+        }
+        self.verbose(&format!("running: {:?}", cmd));
+        try_run(cmd, self.is_verbose())
+    }
+
+    /// Runs a command, printing out nice contextual information if it fails.
+    /// Returns false if do not execute at all, otherwise returns its
+    /// `status.success()`.
+    pub(crate) fn check_run(&self, cmd: &mut Command) -> bool {
+        if self.dry_run() {
+            return true;
+        }
+        self.verbose(&format!("running: {:?}", cmd));
+        check_run(cmd, self.is_verbose())
+    }
+
+    /// Modifies the interpreter section of 'fname' to fix the dynamic linker,
+    /// or the RPATH section, to fix the dynamic library search path
+    ///
+    /// This is only required on NixOS and uses the PatchELF utility to
+    /// change the interpreter/RPATH of ELF executables.
+    ///
+    /// Please see https://nixos.org/patchelf.html for more information
+    fn fix_bin_or_dylib(&self, fname: &Path) {
+        // FIXME: cache NixOS detection?
+        match Command::new("uname").arg("-s").stderr(Stdio::inherit()).output() {
+            Err(_) => return,
+            Ok(output) if !output.status.success() => return,
+            Ok(output) => {
+                let mut s = output.stdout;
+                if s.last() == Some(&b'\n') {
+                    s.pop();
+                }
+                if s != b"Linux" {
+                    return;
+                }
+            }
+        }
+
+        // If the user has asked binaries to be patched for Nix, then
+        // don't check for NixOS or `/lib`, just continue to the patching.
+        // NOTE: this intentionally comes after the Linux check:
+        // - patchelf only works with ELF files, so no need to run it on Mac or Windows
+        // - On other Unix systems, there is no stable syscall interface, so Nix doesn't manage the global libc.
+        if !self.patch_binaries_for_nix {
+            // Use `/etc/os-release` instead of `/etc/NIXOS`.
+            // The latter one does not exist on NixOS when using tmpfs as root.
+            const NIX_IDS: &[&str] = &["ID=nixos", "ID='nixos'", "ID=\"nixos\""];
+            let os_release = match File::open("/etc/os-release") {
+                Err(e) if e.kind() == ErrorKind::NotFound => return,
+                Err(e) => panic!("failed to access /etc/os-release: {}", e),
+                Ok(f) => f,
+            };
+            if !BufReader::new(os_release).lines().any(|l| NIX_IDS.contains(&t!(l).trim())) {
+                return;
+            }
+            if Path::new("/lib").exists() {
+                return;
+            }
+        }
+
+        // At this point we're pretty sure the user is running NixOS or using Nix
+        println!("info: you seem to be using Nix. Attempting to patch {}", fname.display());
+
+        // Only build `.nix-deps` once.
+        static NIX_DEPS_DIR: OnceCell<PathBuf> = OnceCell::new();
+        let mut nix_build_succeeded = true;
+        let nix_deps_dir = NIX_DEPS_DIR.get_or_init(|| {
+            // Run `nix-build` to "build" each dependency (which will likely reuse
+            // the existing `/nix/store` copy, or at most download a pre-built copy).
+            //
+            // Importantly, we create a gc-root called `.nix-deps` in the `build/`
+            // directory, but still reference the actual `/nix/store` path in the rpath
+            // as it makes it significantly more robust against changes to the location of
+            // the `.nix-deps` location.
+            //
+            // bintools: Needed for the path of `ld-linux.so` (via `nix-support/dynamic-linker`).
+            // zlib: Needed as a system dependency of `libLLVM-*.so`.
+            // patchelf: Needed for patching ELF binaries (see doc comment above).
+            let nix_deps_dir = self.out.join(".nix-deps");
+            const NIX_EXPR: &str = "
+            with (import <nixpkgs> {});
+            symlinkJoin {
+                name = \"rust-stage0-dependencies\";
+                paths = [
+                    zlib
+                    patchelf
+                    stdenv.cc.bintools
+                ];
+            }
+            ";
+            nix_build_succeeded = self.try_run(Command::new("nix-build").args(&[
+                Path::new("-E"),
+                Path::new(NIX_EXPR),
+                Path::new("-o"),
+                &nix_deps_dir,
+            ]));
+            nix_deps_dir
+        });
+        if !nix_build_succeeded {
+            return;
+        }
+
+        let mut patchelf = Command::new(nix_deps_dir.join("bin/patchelf"));
+        let rpath_entries = {
+            // ORIGIN is a relative default, all binary and dynamic libraries we ship
+            // appear to have this (even when `../lib` is redundant).
+            // NOTE: there are only two paths here, delimited by a `:`
+            let mut entries = OsString::from("$ORIGIN/../lib:");
+            entries.push(t!(fs::canonicalize(nix_deps_dir)));
+            entries.push("/lib");
+            entries
+        };
+        patchelf.args(&[OsString::from("--set-rpath"), rpath_entries]);
+        if !fname.extension().map_or(false, |ext| ext == "so") {
+            // Finally, set the correct .interp for binaries
+            let dynamic_linker_path = nix_deps_dir.join("nix-support/dynamic-linker");
+            // FIXME: can we support utf8 here? `args` doesn't accept Vec<u8>, only OsString ...
+            let dynamic_linker = t!(String::from_utf8(t!(fs::read(dynamic_linker_path))));
+            patchelf.args(&["--set-interpreter", dynamic_linker.trim_end()]);
+        }
+
+        self.try_run(patchelf.arg(fname));
+    }
+
+    fn download_file(&self, url: &str, dest_path: &Path, help_on_error: &str) {
+        self.verbose(&format!("download {url}"));
+        // Use a temporary file in case we crash while downloading, to avoid a corrupt download in cache/.
+        let tempfile = self.tempdir().join(dest_path.file_name().unwrap());
+        // While bootstrap itself only supports http and https downloads, downstream forks might
+        // need to download components from other protocols. The match allows them adding more
+        // protocols without worrying about merge conflicts if we change the HTTP implementation.
+        match url.split_once("://").map(|(proto, _)| proto) {
+            Some("http") | Some("https") => {
+                self.download_http_with_retries(&tempfile, url, help_on_error)
+            }
+            Some(other) => panic!("unsupported protocol {other} in {url}"),
+            None => panic!("no protocol in {url}"),
+        }
+        t!(std::fs::rename(&tempfile, dest_path));
+    }
+
+    fn download_http_with_retries(&self, tempfile: &Path, url: &str, help_on_error: &str) {
+        println!("downloading {}", url);
+        // Try curl. If that fails and we are on windows, fallback to PowerShell.
+        let mut curl = Command::new("curl");
+        curl.args(&[
+            "-#",
+            "-y",
+            "30",
+            "-Y",
+            "10", // timeout if speed is < 10 bytes/sec for > 30 seconds
+            "--connect-timeout",
+            "30", // timeout if cannot connect within 30 seconds
+            "--retry",
+            "3",
+            "-Sf",
+            "-o",
+        ]);
+        curl.arg(tempfile);
+        curl.arg(url);
+        if !self.check_run(&mut curl) {
+            if self.build.contains("windows-msvc") {
+                println!("Fallback to PowerShell");
+                for _ in 0..3 {
+                    if self.try_run(Command::new("PowerShell.exe").args(&[
+                        "/nologo",
+                        "-Command",
+                        "[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;",
+                        &format!(
+                            "(New-Object System.Net.WebClient).DownloadFile('{}', '{}')",
+                            url, tempfile.to_str().expect("invalid UTF-8 not supported with powershell downloads"),
+                        ),
+                    ])) {
+                        return;
+                    }
+                    println!("\nspurious failure, trying again");
+                }
+            }
+            if !help_on_error.is_empty() {
+                eprintln!("{}", help_on_error);
+            }
+            crate::detail_exit(1);
+        }
+    }
+
+    fn unpack(&self, tarball: &Path, dst: &Path, pattern: &str) {
+        println!("extracting {} to {}", tarball.display(), dst.display());
+        if !dst.exists() {
+            t!(fs::create_dir_all(dst));
+        }
+
+        // `tarball` ends with `.tar.xz`; strip that suffix
+        // example: `rust-dev-nightly-x86_64-unknown-linux-gnu`
+        let uncompressed_filename =
+            Path::new(tarball.file_name().expect("missing tarball filename")).file_stem().unwrap();
+        let directory_prefix = Path::new(Path::new(uncompressed_filename).file_stem().unwrap());
+
+        // decompress the file
+        let data = t!(File::open(tarball));
+        let decompressor = XzDecoder::new(BufReader::new(data));
+
+        let mut tar = tar::Archive::new(decompressor);
+        for member in t!(tar.entries()) {
+            let mut member = t!(member);
+            let original_path = t!(member.path()).into_owned();
+            // skip the top-level directory
+            if original_path == directory_prefix {
+                continue;
+            }
+            let mut short_path = t!(original_path.strip_prefix(directory_prefix));
+            if !short_path.starts_with(pattern) {
+                continue;
+            }
+            short_path = t!(short_path.strip_prefix(pattern));
+            let dst_path = dst.join(short_path);
+            self.verbose(&format!("extracting {} to {}", original_path.display(), dst.display()));
+            if !t!(member.unpack_in(dst)) {
+                panic!("path traversal attack ??");
+            }
+            let src_path = dst.join(original_path);
+            if src_path.is_dir() && dst_path.exists() {
+                continue;
+            }
+            t!(fs::rename(src_path, dst_path));
+        }
+        t!(fs::remove_dir_all(dst.join(directory_prefix)));
+    }
+
+    /// Returns whether the SHA256 checksum of `path` matches `expected`.
+    fn verify(&self, path: &Path, expected: &str) -> bool {
+        use sha2::Digest;
+
+        self.verbose(&format!("verifying {}", path.display()));
+        let mut hasher = sha2::Sha256::new();
+        // FIXME: this is ok for rustfmt (4.1 MB large at time of writing), but it seems memory-intensive for rustc and larger components.
+        // Consider using streaming IO instead?
+        let contents = if self.dry_run() { vec![] } else { t!(fs::read(path)) };
+        hasher.update(&contents);
+        let found = hex::encode(hasher.finalize().as_slice());
+        let verified = found == expected;
+        if !verified && !self.dry_run() {
+            println!(
+                "invalid checksum: \n\
+                found:    {found}\n\
+                expected: {expected}",
+            );
+        }
+        return verified;
+    }
+}
+
+enum DownloadSource {
+    CI,
+    Dist,
+}
+
+/// Functions that are only ever called once, but named for clarify and to avoid thousand-line functions.
+impl Config {
+    pub(crate) fn maybe_download_rustfmt(&self) -> Option<PathBuf> {
+        let RustfmtMetadata { date, version } = self.stage0_metadata.rustfmt.as_ref()?;
+        let channel = format!("{version}-{date}");
+
+        let host = self.build;
+        let rustfmt_path = self.initial_rustc.with_file_name(exe("rustfmt", host));
+        let bin_root = self.out.join(host.triple).join("stage0");
+        let rustfmt_stamp = bin_root.join(".rustfmt-stamp");
+        if rustfmt_path.exists() && !program_out_of_date(&rustfmt_stamp, &channel) {
+            return Some(rustfmt_path);
+        }
+
+        let filename = format!("rustfmt-{version}-{build}.tar.xz", build = host.triple);
+        self.download_component(DownloadSource::Dist, filename, "rustfmt-preview", &date, "stage0");
+
+        self.fix_bin_or_dylib(&bin_root.join("bin").join("rustfmt"));
+        self.fix_bin_or_dylib(&bin_root.join("bin").join("cargo-fmt"));
+
+        self.create(&rustfmt_stamp, &channel);
+        Some(rustfmt_path)
+    }
+
+    pub(crate) fn download_ci_rustc(&self, commit: &str) {
+        self.verbose(&format!("using downloaded stage2 artifacts from CI (commit {commit})"));
+        let version = self.artifact_version_part(commit);
+        let host = self.build.triple;
+        let bin_root = self.out.join(host).join("ci-rustc");
+        let rustc_stamp = bin_root.join(".rustc-stamp");
+
+        if !bin_root.join("bin").join("rustc").exists() || program_out_of_date(&rustc_stamp, commit)
+        {
+            if bin_root.exists() {
+                t!(fs::remove_dir_all(&bin_root));
+            }
+            let filename = format!("rust-std-{version}-{host}.tar.xz");
+            let pattern = format!("rust-std-{host}");
+            self.download_ci_component(filename, &pattern, commit);
+            let filename = format!("rustc-{version}-{host}.tar.xz");
+            self.download_ci_component(filename, "rustc", commit);
+            // download-rustc doesn't need its own cargo, it can just use beta's.
+            let filename = format!("rustc-dev-{version}-{host}.tar.xz");
+            self.download_ci_component(filename, "rustc-dev", commit);
+            let filename = format!("rust-src-{version}.tar.xz");
+            self.download_ci_component(filename, "rust-src", commit);
+
+            self.fix_bin_or_dylib(&bin_root.join("bin").join("rustc"));
+            self.fix_bin_or_dylib(&bin_root.join("bin").join("rustdoc"));
+            self.fix_bin_or_dylib(&bin_root.join("libexec").join("rust-analyzer-proc-macro-srv"));
+            let lib_dir = bin_root.join("lib");
+            for lib in t!(fs::read_dir(&lib_dir), lib_dir.display().to_string()) {
+                let lib = t!(lib);
+                if lib.path().extension() == Some(OsStr::new("so")) {
+                    self.fix_bin_or_dylib(&lib.path());
+                }
+            }
+            t!(fs::write(rustc_stamp, commit));
+        }
+    }
+
+    /// Download a single component of a CI-built toolchain (not necessarily a published nightly).
+    // NOTE: intentionally takes an owned string to avoid downloading multiple times by accident
+    fn download_ci_component(&self, filename: String, prefix: &str, commit: &str) {
+        Self::download_component(self, DownloadSource::CI, filename, prefix, commit, "ci-rustc")
+    }
+
+    fn download_component(
+        &self,
+        mode: DownloadSource,
+        filename: String,
+        prefix: &str,
+        key: &str,
+        destination: &str,
+    ) {
+        let cache_dst = self.out.join("cache");
+        let cache_dir = cache_dst.join(key);
+        if !cache_dir.exists() {
+            t!(fs::create_dir_all(&cache_dir));
+        }
+
+        let bin_root = self.out.join(self.build.triple).join(destination);
+        let tarball = cache_dir.join(&filename);
+        let (base_url, url, should_verify) = match mode {
+            DownloadSource::CI => (
+                self.stage0_metadata.config.artifacts_server.clone(),
+                format!("{key}/{filename}"),
+                false,
+            ),
+            DownloadSource::Dist => {
+                let dist_server = env::var("RUSTUP_DIST_SERVER")
+                    .unwrap_or(self.stage0_metadata.config.dist_server.to_string());
+                // NOTE: make `dist` part of the URL because that's how it's stored in src/stage0.json
+                (dist_server, format!("dist/{key}/{filename}"), true)
+            }
+        };
+
+        // For the beta compiler, put special effort into ensuring the checksums are valid.
+        // FIXME: maybe we should do this for download-rustc as well? but it would be a pain to update
+        // this on each and every nightly ...
+        let checksum = if should_verify {
+            let error = format!(
+                "src/stage0.json doesn't contain a checksum for {url}. \
+                Pre-built artifacts might not be available for this \
+                target at this time, see https://doc.rust-lang.org/nightly\
+                /rustc/platform-support.html for more information."
+            );
+            let sha256 = self.stage0_metadata.checksums_sha256.get(&url).expect(&error);
+            if tarball.exists() {
+                if self.verify(&tarball, sha256) {
+                    self.unpack(&tarball, &bin_root, prefix);
+                    return;
+                } else {
+                    self.verbose(&format!(
+                        "ignoring cached file {} due to failed verification",
+                        tarball.display()
+                    ));
+                    self.remove(&tarball);
+                }
+            }
+            Some(sha256)
+        } else if tarball.exists() {
+            self.unpack(&tarball, &bin_root, prefix);
+            return;
+        } else {
+            None
+        };
+
+        self.download_file(&format!("{base_url}/{url}"), &tarball, "");
+        if let Some(sha256) = checksum {
+            if !self.verify(&tarball, sha256) {
+                panic!("failed to verify {}", tarball.display());
+            }
+        }
+
+        self.unpack(&tarball, &bin_root, prefix);
+    }
+
+    pub(crate) fn maybe_download_ci_llvm(&self) {
+        if !self.llvm_from_ci {
+            return;
+        }
+        let llvm_root = self.ci_llvm_root();
+        let llvm_stamp = llvm_root.join(".llvm-stamp");
+        let llvm_sha = detect_llvm_sha(&self, self.rust_info.is_managed_git_subrepository());
+        let key = format!("{}{}", llvm_sha, self.llvm_assertions);
+        if program_out_of_date(&llvm_stamp, &key) && !self.dry_run() {
+            self.download_ci_llvm(&llvm_sha);
+            for entry in t!(fs::read_dir(llvm_root.join("bin"))) {
+                self.fix_bin_or_dylib(&t!(entry).path());
+            }
+
+            // Update the timestamp of llvm-config to force rustc_llvm to be
+            // rebuilt. This is a hacky workaround for a deficiency in Cargo where
+            // the rerun-if-changed directive doesn't handle changes very well.
+            // https://github.com/rust-lang/cargo/issues/10791
+            // Cargo only compares the timestamp of the file relative to the last
+            // time `rustc_llvm` build script ran. However, the timestamps of the
+            // files in the tarball are in the past, so it doesn't trigger a
+            // rebuild.
+            let now = filetime::FileTime::from_system_time(std::time::SystemTime::now());
+            let llvm_config = llvm_root.join("bin").join(exe("llvm-config", self.build));
+            t!(filetime::set_file_times(&llvm_config, now, now));
+
+            let llvm_lib = llvm_root.join("lib");
+            for entry in t!(fs::read_dir(&llvm_lib)) {
+                let lib = t!(entry).path();
+                if lib.extension().map_or(false, |ext| ext == "so") {
+                    self.fix_bin_or_dylib(&lib);
+                }
+            }
+            t!(fs::write(llvm_stamp, key));
+        }
+    }
+
+    fn download_ci_llvm(&self, llvm_sha: &str) {
+        let llvm_assertions = self.llvm_assertions;
+
+        let cache_prefix = format!("llvm-{}-{}", llvm_sha, llvm_assertions);
+        let cache_dst = self.out.join("cache");
+        let rustc_cache = cache_dst.join(cache_prefix);
+        if !rustc_cache.exists() {
+            t!(fs::create_dir_all(&rustc_cache));
+        }
+        let base = if llvm_assertions {
+            &self.stage0_metadata.config.artifacts_with_llvm_assertions_server
+        } else {
+            &self.stage0_metadata.config.artifacts_server
+        };
+        let version = self.artifact_version_part(llvm_sha);
+        let filename = format!("rust-dev-{}-{}.tar.xz", version, self.build.triple);
+        let tarball = rustc_cache.join(&filename);
+        if !tarball.exists() {
+            let help_on_error = "error: failed to download llvm from ci
+
+    help: old builds get deleted after a certain time
+    help: if trying to compile an old commit of rustc, disable `download-ci-llvm` in config.toml:
+
+    [llvm]
+    download-ci-llvm = false
+    ";
+            self.download_file(&format!("{base}/{llvm_sha}/{filename}"), &tarball, help_on_error);
+        }
+        let llvm_root = self.ci_llvm_root();
+        self.unpack(&tarball, &llvm_root, "rust-dev");
+    }
+}
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index ee341a353..37a8eb884 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -140,9 +140,10 @@ pub enum Subcommand {
     },
     Run {
         paths: Vec<PathBuf>,
+        args: Vec<String>,
     },
     Setup {
-        profile: Profile,
+        profile: Option<Profile>,
     },
 }
 
@@ -342,6 +343,9 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
             Kind::Format => {
                 opts.optflag("", "check", "check formatting instead of applying.");
             }
+            Kind::Run => {
+                opts.optmulti("", "args", "arguments for the tool", "ARGS");
+            }
             _ => {}
         };
 
@@ -613,7 +617,7 @@ Arguments:
                     println!("\nrun requires at least a path!\n");
                     usage(1, &opts, verbose, &subcommand_help);
                 }
-                Subcommand::Run { paths }
+                Subcommand::Run { paths, args: matches.opt_strs("args") }
             }
             Kind::Setup => {
                 let profile = if paths.len() > 1 {
@@ -624,14 +628,15 @@ Arguments:
                         |path| format!("{} is not a valid UTF8 string", path.to_string_lossy())
                     ));
 
-                    profile_string.parse().unwrap_or_else(|err| {
+                    let profile = profile_string.parse().unwrap_or_else(|err| {
                         eprintln!("error: {}", err);
                         eprintln!("help: the available profiles are:");
                         eprint!("{}", Profile::all_for_help("- "));
                         crate::detail_exit(1);
-                    })
+                    });
+                    Some(profile)
                 } else {
-                    t!(crate::setup::interactive_path())
+                    None
                 };
                 Subcommand::Setup { profile }
             }
@@ -721,16 +726,12 @@ impl Subcommand {
     }
 
     pub fn test_args(&self) -> Vec<&str> {
-        let mut args = vec![];
-
         match *self {
             Subcommand::Test { ref test_args, .. } | Subcommand::Bench { ref test_args, .. } => {
-                args.extend(test_args.iter().flat_map(|s| s.split_whitespace()))
+                test_args.iter().flat_map(|s| s.split_whitespace()).collect()
             }
-            _ => (),
+            _ => vec![],
         }
-
-        args
     }
 
     pub fn rustc_args(&self) -> Vec<&str> {
@@ -738,7 +739,16 @@ impl Subcommand {
             Subcommand::Test { ref rustc_args, .. } => {
                 rustc_args.iter().flat_map(|s| s.split_whitespace()).collect()
             }
-            _ => Vec::new(),
+            _ => vec![],
+        }
+    }
+
+    pub fn args(&self) -> Vec<&str> {
+        match *self {
+            Subcommand::Run { ref args, .. } => {
+                args.iter().flat_map(|s| s.split_whitespace()).collect()
+            }
+            _ => vec![],
         }
     }
 
diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index 37322670e..5e7264fe7 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -43,7 +43,7 @@ struct RustfmtConfig {
 }
 
 pub fn format(build: &Builder<'_>, check: bool, paths: &[PathBuf]) {
-    if build.config.dry_run {
+    if build.config.dry_run() {
         return;
     }
     let mut builder = ignore::types::TypesBuilder::new();
diff --git a/src/bootstrap/install.rs b/src/bootstrap/install.rs
index 7672b7c91..38426f3a4 100644
--- a/src/bootstrap/install.rs
+++ b/src/bootstrap/install.rs
@@ -200,10 +200,14 @@ install!((self, builder, _config),
         install_sh(builder, "clippy", self.compiler.stage, Some(self.target), &tarball);
     };
     Miri, alias = "miri", Self::should_build(_config), only_hosts: true, {
-        let tarball = builder
-            .ensure(dist::Miri { compiler: self.compiler, target: self.target })
-            .expect("missing miri");
-        install_sh(builder, "miri", self.compiler.stage, Some(self.target), &tarball);
+        if let Some(tarball) = builder.ensure(dist::Miri { compiler: self.compiler, target: self.target }) {
+            install_sh(builder, "miri", self.compiler.stage, Some(self.target), &tarball);
+        } else {
+            // Miri is only available on nightly
+            builder.info(
+                &format!("skipping Install miri stage{} ({})", self.compiler.stage, self.target),
+            );
+        }
     };
     Rustfmt, alias = "rustfmt", Self::should_build(_config), only_hosts: true, {
         if let Some(tarball) = builder.ensure(dist::Rustfmt {
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 7e70e99bb..3ed534523 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -112,15 +112,14 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::str;
 
-use config::Target;
+use channel::GitInfo;
+use config::{DryRun, Target};
 use filetime::FileTime;
 use once_cell::sync::OnceCell;
 
 use crate::builder::Kind;
 use crate::config::{LlvmLibunwind, TargetSelection};
-use crate::util::{
-    check_run, exe, libdir, mtime, output, run, run_suppressed, try_run, try_run_suppressed, CiEnv,
-};
+use crate::util::{exe, libdir, mtime, output, run, run_suppressed, try_run_suppressed, CiEnv};
 
 mod bolt;
 mod builder;
@@ -133,6 +132,7 @@ mod compile;
 mod config;
 mod dist;
 mod doc;
+mod download;
 mod flags;
 mod format;
 mod install;
@@ -281,7 +281,6 @@ pub struct Build {
     src: PathBuf,
     out: PathBuf,
     bootstrap_out: PathBuf,
-    rust_info: channel::GitInfo,
     cargo_info: channel::GitInfo,
     rust_analyzer_info: channel::GitInfo,
     clippy_info: channel::GitInfo,
@@ -396,6 +395,28 @@ pub enum CLang {
     Cxx,
 }
 
+macro_rules! forward {
+    ( $( $fn:ident( $($param:ident: $ty:ty),* ) $( -> $ret:ty)? ),+ $(,)? ) => {
+        impl Build {
+            $( fn $fn(&self, $($param: $ty),* ) $( -> $ret)? {
+                self.config.$fn( $($param),* )
+            } )+
+        }
+    }
+}
+
+forward! {
+    verbose(msg: &str),
+    is_verbose() -> bool,
+    create(path: &Path, s: &str),
+    remove(f: &Path),
+    tempdir() -> PathBuf,
+    try_run(cmd: &mut Command) -> bool,
+    llvm_link_shared() -> bool,
+    download_rustc() -> bool,
+    initial_rustfmt() -> Option<PathBuf>,
+}
+
 impl Build {
     /// Creates a new set of build configuration from the `flags` on the command
     /// line and the filesystem `config`.
@@ -430,7 +451,7 @@ impl Build {
         // we always try to use git for LLVM builds
         let in_tree_llvm_info = channel::GitInfo::new(false, &src.join("src/llvm-project"));
 
-        let initial_target_libdir_str = if config.dry_run {
+        let initial_target_libdir_str = if config.dry_run() {
             "/dummy/lib/path/to/lib/".to_string()
         } else {
             output(
@@ -444,7 +465,7 @@ impl Build {
         let initial_target_dir = Path::new(&initial_target_libdir_str).parent().unwrap();
         let initial_lld = initial_target_dir.join("bin").join("rust-lld");
 
-        let initial_sysroot = if config.dry_run {
+        let initial_sysroot = if config.dry_run() {
             "/dummy".to_string()
         } else {
             output(Command::new(&config.initial_rustc).arg("--print").arg("sysroot"))
@@ -499,7 +520,6 @@ impl Build {
             out,
             bootstrap_out,
 
-            rust_info,
             cargo_info,
             rust_analyzer_info,
             clippy_info,
@@ -522,16 +542,6 @@ impl Build {
             metrics: metrics::BuildMetrics::init(),
         };
 
-        build.verbose("finding compilers");
-        cc_detect::find(&mut build);
-        // When running `setup`, the profile is about to change, so any requirements we have now may
-        // be different on the next invocation. Don't check for them until the next time x.py is
-        // run. This is ok because `setup` never runs any build commands, so it won't fail if commands are missing.
-        if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
-            build.verbose("running sanity check");
-            sanity::check(&mut build);
-        }
-
         // If local-rust is the same major.minor as the current version, then force a
         // local-rebuild
         let local_version_verbose =
@@ -547,16 +557,34 @@ impl Build {
             build.local_rebuild = true;
         }
 
-        // Make sure we update these before gathering metadata so we don't get an error about missing
-        // Cargo.toml files.
-        let rust_submodules =
-            ["src/tools/rust-installer", "src/tools/cargo", "library/backtrace", "library/stdarch"];
-        for s in rust_submodules {
-            build.update_submodule(Path::new(s));
-        }
+        build.verbose("finding compilers");
+        cc_detect::find(&mut build);
+        // When running `setup`, the profile is about to change, so any requirements we have now may
+        // be different on the next invocation. Don't check for them until the next time x.py is
+        // run. This is ok because `setup` never runs any build commands, so it won't fail if commands are missing.
+        //
+        // Similarly, for `setup` we don't actually need submodules or cargo metadata.
+        if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
+            build.verbose("running sanity check");
+            sanity::check(&mut build);
+
+            // Make sure we update these before gathering metadata so we don't get an error about missing
+            // Cargo.toml files.
+            let rust_submodules = [
+                "src/tools/rust-installer",
+                "src/tools/cargo",
+                "library/backtrace",
+                "library/stdarch",
+            ];
+            for s in rust_submodules {
+                build.update_submodule(Path::new(s));
+            }
+            // Now, update all existing submodules.
+            build.update_existing_submodules();
 
-        build.verbose("learning about cargo");
-        metadata::build(&mut build);
+            build.verbose("learning about cargo");
+            metadata::build(&mut build);
+        }
 
         build
     }
@@ -570,7 +598,7 @@ impl Build {
             t!(std::fs::read_dir(dir)).next().is_none()
         }
 
-        if !self.config.submodules(&self.rust_info) {
+        if !self.config.submodules(&self.rust_info()) {
             return;
         }
 
@@ -628,15 +656,29 @@ impl Build {
             self.run(&mut update(false));
         }
 
+        // Save any local changes, but avoid running `git stash pop` if there are none (since it will exit with an error).
+        let has_local_modifications = !self.try_run(
+            Command::new("git")
+                .args(&["diff-index", "--quiet", "HEAD"])
+                .current_dir(&absolute_path),
+        );
+        if has_local_modifications {
+            self.run(Command::new("git").args(&["stash", "push"]).current_dir(&absolute_path));
+        }
+
         self.run(Command::new("git").args(&["reset", "-q", "--hard"]).current_dir(&absolute_path));
-        self.run(Command::new("git").args(&["clean", "-qdfx"]).current_dir(absolute_path));
+        self.run(Command::new("git").args(&["clean", "-qdfx"]).current_dir(&absolute_path));
+
+        if has_local_modifications {
+            self.run(Command::new("git").args(&["stash", "pop"]).current_dir(absolute_path));
+        }
     }
 
     /// If any submodule has been initialized already, sync it unconditionally.
     /// This avoids contributors checking in a submodule change by accident.
-    pub fn maybe_update_submodules(&self) {
+    pub fn update_existing_submodules(&self) {
         // Avoid running git when there isn't a git checkout.
-        if !self.config.submodules(&self.rust_info) {
+        if !self.config.submodules(&self.rust_info()) {
             return;
         }
         let output = output(
@@ -663,8 +705,6 @@ impl Build {
             job::setup(self);
         }
 
-        self.maybe_update_submodules();
-
         if let Subcommand::Format { check, paths } = &self.config.cmd {
             return format::format(&builder::Builder::new(&self), *check, &paths);
         }
@@ -689,13 +729,13 @@ impl Build {
             }
         }
 
-        if !self.config.dry_run {
+        if !self.config.dry_run() {
             {
-                self.config.dry_run = true;
+                self.config.dry_run = DryRun::SelfCheck;
                 let builder = builder::Builder::new(&self);
                 builder.execute_cli();
             }
-            self.config.dry_run = false;
+            self.config.dry_run = DryRun::Disabled;
             let builder = builder::Builder::new(&self);
             builder.execute_cli();
         } else {
@@ -735,6 +775,10 @@ impl Build {
         cleared
     }
 
+    fn rust_info(&self) -> &GitInfo {
+        &self.config.rust_info
+    }
+
     /// Gets the space-separated set of activated features for the standard
     /// library.
     fn std_features(&self, target: TargetSelection) -> String {
@@ -947,7 +991,7 @@ impl Build {
 
     /// Runs a command, printing out nice contextual information if it fails.
     fn run(&self, cmd: &mut Command) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         self.verbose(&format!("running: {:?}", cmd));
@@ -956,7 +1000,7 @@ impl Build {
 
     /// Runs a command, printing out nice contextual information if it fails.
     fn run_quiet(&self, cmd: &mut Command) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         self.verbose(&format!("running: {:?}", cmd));
@@ -966,47 +1010,14 @@ impl Build {
     /// Runs a command, printing out nice contextual information if it fails.
     /// Exits if the command failed to execute at all, otherwise returns its
     /// `status.success()`.
-    fn try_run(&self, cmd: &mut Command) -> bool {
-        if self.config.dry_run {
-            return true;
-        }
-        self.verbose(&format!("running: {:?}", cmd));
-        try_run(cmd, self.is_verbose())
-    }
-
-    /// Runs a command, printing out nice contextual information if it fails.
-    /// Exits if the command failed to execute at all, otherwise returns its
-    /// `status.success()`.
     fn try_run_quiet(&self, cmd: &mut Command) -> bool {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return true;
         }
         self.verbose(&format!("running: {:?}", cmd));
         try_run_suppressed(cmd)
     }
 
-    /// Runs a command, printing out nice contextual information if it fails.
-    /// Returns false if do not execute at all, otherwise returns its
-    /// `status.success()`.
-    fn check_run(&self, cmd: &mut Command) -> bool {
-        if self.config.dry_run {
-            return true;
-        }
-        self.verbose(&format!("running: {:?}", cmd));
-        check_run(cmd, self.is_verbose())
-    }
-
-    pub fn is_verbose(&self) -> bool {
-        self.verbosity > 0
-    }
-
-    /// Prints a message if this build is configured in verbose mode.
-    fn verbose(&self, msg: &str) {
-        if self.is_verbose() {
-            println!("{}", msg);
-        }
-    }
-
     pub fn is_verbose_than(&self, level: usize) -> bool {
         self.verbosity > level
     }
@@ -1019,10 +1030,12 @@ impl Build {
     }
 
     fn info(&self, msg: &str) {
-        if self.config.dry_run {
-            return;
+        match self.config.dry_run {
+            DryRun::SelfCheck => return,
+            DryRun::Disabled | DryRun::UserSelected => {
+                println!("{}", msg);
+            }
         }
-        println!("{}", msg);
     }
 
     /// Returns the number of parallel jobs that have been configured for this
@@ -1152,8 +1165,8 @@ impl Build {
                 options[0] = Some("-Clink-arg=-fuse-ld=lld".to_string());
             }
 
-            let threads = if target.contains("windows") { "/threads:1" } else { "--threads=1" };
-            options[1] = Some(format!("-Clink-arg=-Wl,{}", threads));
+            let no_threads = util::lld_flag_no_threads(target.contains("windows"));
+            options[1] = Some(format!("-Clink-arg=-Wl,{}", no_threads));
         }
 
         IntoIterator::into_iter(options).flatten()
@@ -1267,7 +1280,7 @@ impl Build {
         match &self.config.channel[..] {
             "stable" => num.to_string(),
             "beta" => {
-                if self.rust_info.is_managed_git_subrepository() && !self.config.ignore_git {
+                if self.rust_info().is_managed_git_subrepository() && !self.config.ignore_git {
                     format!("{}-beta.{}", num, self.beta_prerelease_version())
                 } else {
                     format!("{}-beta", num)
@@ -1327,7 +1340,7 @@ impl Build {
     /// Note that this is a descriptive string which includes the commit date,
     /// sha, version, etc.
     fn rust_version(&self) -> String {
-        let mut version = self.rust_info.version(self, &self.version);
+        let mut version = self.rust_info().version(self, &self.version);
         if let Some(ref s) = self.config.description {
             version.push_str(" (");
             version.push_str(s);
@@ -1338,7 +1351,7 @@ impl Build {
 
     /// Returns the full commit hash.
     fn rust_sha(&self) -> Option<&str> {
-        self.rust_info.sha()
+        self.rust_info().sha()
     }
 
     /// Returns the `a.b.c` version that the given package is at.
@@ -1400,7 +1413,7 @@ impl Build {
     }
 
     fn read_stamp_file(&self, stamp: &Path) -> Vec<(PathBuf, DependencyType)> {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return Vec::new();
         }
 
@@ -1424,23 +1437,13 @@ impl Build {
         paths
     }
 
-    /// Create a temporary directory in `out` and return its path.
-    ///
-    /// NOTE: this temporary directory is shared between all steps;
-    /// if you need an empty directory, create a new subdirectory inside it.
-    fn tempdir(&self) -> PathBuf {
-        let tmp = self.out.join("tmp");
-        t!(fs::create_dir_all(&tmp));
-        tmp
-    }
-
     /// Copies a file from `src` to `dst`
     pub fn copy(&self, src: &Path, dst: &Path) {
         self.copy_internal(src, dst, false);
     }
 
     fn copy_internal(&self, src: &Path, dst: &Path, dereference_symlinks: bool) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         self.verbose_than(1, &format!("Copy {:?} to {:?}", src, dst));
@@ -1477,7 +1480,7 @@ impl Build {
     /// Copies the `src` directory recursively to `dst`. Both are assumed to exist
     /// when this function is called.
     pub fn cp_r(&self, src: &Path, dst: &Path) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         for f in self.read_dir(src) {
@@ -1530,7 +1533,7 @@ impl Build {
     }
 
     fn install(&self, src: &Path, dstdir: &Path, perms: u32) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         let dst = dstdir.join(src.file_name().unwrap());
@@ -1543,29 +1546,22 @@ impl Build {
         chmod(&dst, perms);
     }
 
-    fn create(&self, path: &Path, s: &str) {
-        if self.config.dry_run {
-            return;
-        }
-        t!(fs::write(path, s));
-    }
-
     fn read(&self, path: &Path) -> String {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return String::new();
         }
         t!(fs::read_to_string(path))
     }
 
     fn create_dir(&self, dir: &Path) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         t!(fs::create_dir_all(dir))
     }
 
     fn remove_dir(&self, dir: &Path) {
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         t!(fs::remove_dir_all(dir))
@@ -1574,7 +1570,7 @@ impl Build {
     fn read_dir(&self, dir: &Path) -> impl Iterator<Item = fs::DirEntry> {
         let iter = match fs::read_dir(dir) {
             Ok(v) => v,
-            Err(_) if self.config.dry_run => return vec![].into_iter(),
+            Err(_) if self.config.dry_run() => return vec![].into_iter(),
             Err(err) => panic!("could not read dir {:?}: {:?}", dir, err),
         };
         iter.map(|e| t!(e)).collect::<Vec<_>>().into_iter()
@@ -1585,14 +1581,7 @@ impl Build {
         use std::os::unix::fs::symlink as symlink_file;
         #[cfg(windows)]
         use std::os::windows::fs::symlink_file;
-        if !self.config.dry_run { symlink_file(src.as_ref(), link.as_ref()) } else { Ok(()) }
-    }
-
-    fn remove(&self, f: &Path) {
-        if self.config.dry_run {
-            return;
-        }
-        fs::remove_file(f).unwrap_or_else(|_| panic!("failed to remove {:?}", f));
+        if !self.config.dry_run() { symlink_file(src.as_ref(), link.as_ref()) } else { Ok(()) }
     }
 
     /// Returns if config.ninja is enabled, and checks for ninja existence,
diff --git a/src/bootstrap/metrics.rs b/src/bootstrap/metrics.rs
index 451febddc..c823dc796 100644
--- a/src/bootstrap/metrics.rs
+++ b/src/bootstrap/metrics.rs
@@ -97,7 +97,7 @@ impl BuildMetrics {
             cpu_threads_count: system.cpus().len(),
             cpu_model: system.cpus()[0].brand().into(),
 
-            memory_total_bytes: system.total_memory() * 1024,
+            memory_total_bytes: system.total_memory(),
         };
         let steps = std::mem::take(&mut state.finished_steps);
 
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 2f856c276..f6c453ebe 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -19,9 +19,9 @@ use std::process::Command;
 use crate::bolt::{instrument_with_bolt_inplace, optimize_library_with_bolt_inplace};
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::channel;
-use crate::config::TargetSelection;
+use crate::config::{Config, TargetSelection};
 use crate::util::get_clang_cl_resource_dir;
-use crate::util::{self, exe, output, program_out_of_date, t, up_to_date};
+use crate::util::{self, exe, output, t, up_to_date};
 use crate::{CLang, GitRepo};
 
 pub struct Meta {
@@ -65,7 +65,7 @@ pub fn prebuilt_llvm_config(
     builder: &Builder<'_>,
     target: TargetSelection,
 ) -> Result<PathBuf, Meta> {
-    maybe_download_ci_llvm(builder);
+    builder.config.maybe_download_ci_llvm();
 
     // If we're using a custom LLVM bail out here, but we can only use a
     // custom LLVM for the build triple.
@@ -117,7 +117,7 @@ pub fn prebuilt_llvm_config(
 }
 
 /// This retrieves the LLVM sha we *want* to use, according to git history.
-pub(crate) fn detect_llvm_sha(config: &crate::config::Config, is_git: bool) -> String {
+pub(crate) fn detect_llvm_sha(config: &Config, is_git: bool) -> String {
     let llvm_sha = if is_git {
         let mut rev_list = config.git();
         rev_list.args(&[
@@ -155,7 +155,7 @@ pub(crate) fn detect_llvm_sha(config: &crate::config::Config, is_git: bool) -> S
 /// This checks both the build triple platform to confirm we're usable at all,
 /// and then verifies if the current HEAD matches the detected LLVM SHA head,
 /// in which case LLVM is indicated as not available.
-pub(crate) fn is_ci_llvm_available(config: &crate::config::Config, asserts: bool) -> bool {
+pub(crate) fn is_ci_llvm_available(config: &Config, asserts: bool) -> bool {
     // This is currently all tier 1 targets and tier 2 targets with host tools
     // (since others may not have CI artifacts)
     // https://doc.rust-lang.org/rustc/platform-support.html#tier-1
@@ -217,80 +217,6 @@ pub(crate) fn is_ci_llvm_available(config: &crate::config::Config, asserts: bool
     true
 }
 
-pub(crate) fn maybe_download_ci_llvm(builder: &Builder<'_>) {
-    let config = &builder.config;
-    if !config.llvm_from_ci {
-        return;
-    }
-    let llvm_root = config.ci_llvm_root();
-    let llvm_stamp = llvm_root.join(".llvm-stamp");
-    let llvm_sha = detect_llvm_sha(&config, builder.rust_info.is_managed_git_subrepository());
-    let key = format!("{}{}", llvm_sha, config.llvm_assertions);
-    if program_out_of_date(&llvm_stamp, &key) && !config.dry_run {
-        download_ci_llvm(builder, &llvm_sha);
-        for entry in t!(fs::read_dir(llvm_root.join("bin"))) {
-            builder.fix_bin_or_dylib(&t!(entry).path());
-        }
-
-        // Update the timestamp of llvm-config to force rustc_llvm to be
-        // rebuilt. This is a hacky workaround for a deficiency in Cargo where
-        // the rerun-if-changed directive doesn't handle changes very well.
-        // https://github.com/rust-lang/cargo/issues/10791
-        // Cargo only compares the timestamp of the file relative to the last
-        // time `rustc_llvm` build script ran. However, the timestamps of the
-        // files in the tarball are in the past, so it doesn't trigger a
-        // rebuild.
-        let now = filetime::FileTime::from_system_time(std::time::SystemTime::now());
-        let llvm_config = llvm_root.join("bin").join(exe("llvm-config", builder.config.build));
-        t!(filetime::set_file_times(&llvm_config, now, now));
-
-        let llvm_lib = llvm_root.join("lib");
-        for entry in t!(fs::read_dir(&llvm_lib)) {
-            let lib = t!(entry).path();
-            if lib.extension().map_or(false, |ext| ext == "so") {
-                builder.fix_bin_or_dylib(&lib);
-            }
-        }
-        t!(fs::write(llvm_stamp, key));
-    }
-}
-
-fn download_ci_llvm(builder: &Builder<'_>, llvm_sha: &str) {
-    let llvm_assertions = builder.config.llvm_assertions;
-
-    let cache_prefix = format!("llvm-{}-{}", llvm_sha, llvm_assertions);
-    let cache_dst = builder.out.join("cache");
-    let rustc_cache = cache_dst.join(cache_prefix);
-    if !rustc_cache.exists() {
-        t!(fs::create_dir_all(&rustc_cache));
-    }
-    let base = if llvm_assertions {
-        &builder.config.stage0_metadata.config.artifacts_with_llvm_assertions_server
-    } else {
-        &builder.config.stage0_metadata.config.artifacts_server
-    };
-    let channel = builder.config.artifact_channel(builder, llvm_sha);
-    let filename = format!("rust-dev-{}-{}.tar.xz", channel, builder.build.build.triple);
-    let tarball = rustc_cache.join(&filename);
-    if !tarball.exists() {
-        let help_on_error = "error: failed to download llvm from ci
-
-help: old builds get deleted after a certain time
-help: if trying to compile an old commit of rustc, disable `download-ci-llvm` in config.toml:
-
-[llvm]
-download-ci-llvm = false
-";
-        builder.download_component(
-            &format!("{base}/{llvm_sha}/{filename}"),
-            &tarball,
-            help_on_error,
-        );
-    }
-    let llvm_root = builder.config.ci_llvm_root();
-    builder.unpack(&tarball, &llvm_root, "rust-dev");
-}
-
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct Llvm {
     pub target: TargetSelection,
@@ -505,7 +431,7 @@ impl Step for Llvm {
         // https://llvm.org/docs/HowToCrossCompileLLVM.html
         if target != builder.config.build {
             let llvm_config = builder.ensure(Llvm { target: builder.config.build });
-            if !builder.config.dry_run {
+            if !builder.config.dry_run() {
                 let llvm_bindir = output(Command::new(&llvm_config).arg("--bindir"));
                 let host_bin = Path::new(llvm_bindir.trim());
                 cfg.define(
@@ -519,7 +445,7 @@ impl Step for Llvm {
             if builder.config.llvm_clang {
                 let build_bin = builder.llvm_out(builder.config.build).join("build").join("bin");
                 let clang_tblgen = build_bin.join("clang-tblgen").with_extension(EXE_EXTENSION);
-                if !builder.config.dry_run && !clang_tblgen.exists() {
+                if !builder.config.dry_run() && !clang_tblgen.exists() {
                     panic!("unable to find {}", clang_tblgen.display());
                 }
                 cfg.define("CLANG_TABLEGEN", clang_tblgen);
@@ -553,7 +479,7 @@ impl Step for Llvm {
         //        tools. Figure out how to filter them down and only build the right
         //        tools and libs on all platforms.
 
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return build_llvm_config;
         }
 
@@ -611,7 +537,7 @@ fn check_llvm_version(builder: &Builder<'_>, llvm_config: &Path) {
         return;
     }
 
-    if builder.config.dry_run {
+    if builder.config.dry_run() {
         return;
     }
 
@@ -872,7 +798,7 @@ impl Step for Lld {
 
     /// Compile LLD for `target`.
     fn run(self, builder: &Builder<'_>) -> PathBuf {
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return PathBuf::from("lld-out-dir-test-gen");
         }
         let target = self.target;
@@ -990,7 +916,7 @@ impl Step for TestHelpers {
     /// Compiles the `rust_test_helpers.c` library which we used in various
     /// `run-pass` tests for ABI testing.
     fn run(self, builder: &Builder<'_>) {
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return;
         }
         // The x86_64-fortanix-unknown-sgx target doesn't have a working C
@@ -1066,7 +992,7 @@ impl Step for Sanitizers {
         }
 
         let llvm_config = builder.ensure(Llvm { target: builder.config.build });
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return runtimes;
         }
 
@@ -1240,7 +1166,7 @@ impl Step for CrtBeginEnd {
     fn run(self, builder: &Builder<'_>) -> Self::Output {
         let out_dir = builder.native_dir(self.target).join("crt");
 
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return out_dir;
         }
 
@@ -1304,7 +1230,7 @@ impl Step for Libunwind {
 
     /// Build linunwind.a
     fn run(self, builder: &Builder<'_>) -> Self::Output {
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return PathBuf::new();
         }
 
diff --git a/src/bootstrap/run.rs b/src/bootstrap/run.rs
index 511872903..05de51f8c 100644
--- a/src/bootstrap/run.rs
+++ b/src/bootstrap/run.rs
@@ -1,8 +1,13 @@
+use std::path::PathBuf;
+use std::process::Command;
+
 use crate::builder::{Builder, RunConfig, ShouldRun, Step};
+use crate::config::TargetSelection;
 use crate::dist::distdir;
-use crate::tool::Tool;
+use crate::test;
+use crate::tool::{self, SourceType, Tool};
 use crate::util::output;
-use std::process::Command;
+use crate::Mode;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct ExpandYamlAnchors;
@@ -125,3 +130,125 @@ impl Step for ReplaceVersionPlaceholder {
         builder.run(&mut cmd);
     }
 }
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct Miri {
+    stage: u32,
+    host: TargetSelection,
+    target: TargetSelection,
+}
+
+impl Step for Miri {
+    type Output = ();
+    const ONLY_HOSTS: bool = false;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/miri")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(Miri {
+            stage: run.builder.top_stage,
+            host: run.build_triple(),
+            target: run.target,
+        });
+    }
+
+    fn run(self, builder: &Builder<'_>) {
+        let stage = self.stage;
+        let host = self.host;
+        let target = self.target;
+        let compiler = builder.compiler(stage, host);
+
+        let miri = builder
+            .ensure(tool::Miri { compiler, target: self.host, extra_features: Vec::new() })
+            .expect("in-tree tool");
+        let miri_sysroot = test::Miri::build_miri_sysroot(builder, compiler, &miri, target);
+
+        // # Run miri.
+        // Running it via `cargo run` as that figures out the right dylib path.
+        // add_rustc_lib_path does not add the path that contains librustc_driver-<...>.so.
+        let mut miri = tool::prepare_tool_cargo(
+            builder,
+            compiler,
+            Mode::ToolRustc,
+            host,
+            "run",
+            "src/tools/miri",
+            SourceType::InTree,
+            &[],
+        );
+        miri.add_rustc_lib_path(builder, compiler);
+        // Forward arguments.
+        miri.arg("--").arg("--target").arg(target.rustc_target_arg());
+        miri.args(builder.config.cmd.args());
+
+        // miri tests need to know about the stage sysroot
+        miri.env("MIRI_SYSROOT", &miri_sysroot);
+
+        let mut miri = Command::from(miri);
+        builder.run(&mut miri);
+    }
+}
+
+#[derive(Debug, PartialOrd, Ord, Copy, Clone, Hash, PartialEq, Eq)]
+pub struct CollectLicenseMetadata;
+
+impl Step for CollectLicenseMetadata {
+    type Output = PathBuf;
+    const ONLY_HOSTS: bool = true;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/collect-license-metadata")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(CollectLicenseMetadata);
+    }
+
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
+        let Some(reuse) = &builder.config.reuse else {
+            panic!("REUSE is required to collect the license metadata");
+        };
+
+        // Temporary location, it will be moved to src/etc once it's accurate.
+        let dest = builder.out.join("license-metadata.json");
+
+        let mut cmd = builder.tool_cmd(Tool::CollectLicenseMetadata);
+        cmd.env("REUSE_EXE", reuse);
+        cmd.env("DEST", &dest);
+        builder.run(&mut cmd);
+
+        dest
+    }
+}
+
+#[derive(Debug, PartialOrd, Ord, Copy, Clone, Hash, PartialEq, Eq)]
+pub struct GenerateCopyright;
+
+impl Step for GenerateCopyright {
+    type Output = PathBuf;
+    const ONLY_HOSTS: bool = true;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/generate-copyright")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(GenerateCopyright);
+    }
+
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
+        let license_metadata = builder.ensure(CollectLicenseMetadata);
+
+        // Temporary location, it will be moved to the proper one once it's accurate.
+        let dest = builder.out.join("COPYRIGHT.md");
+
+        let mut cmd = builder.tool_cmd(Tool::GenerateCopyright);
+        cmd.env("LICENSE_METADATA", &license_metadata);
+        cmd.env("DEST", &dest);
+        builder.run(&mut cmd);
+
+        dest
+    }
+}
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index e90551725..8a40b0f64 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -74,7 +74,7 @@ pub fn check(build: &mut Build) {
     let mut cmd_finder = Finder::new();
     // If we've got a git directory we're gonna need git to update
     // submodules and learn about various other aspects.
-    if build.rust_info.is_managed_git_subrepository() {
+    if build.rust_info().is_managed_git_subrepository() {
         cmd_finder.must_have("git");
     }
 
@@ -140,6 +140,13 @@ than building it.
         .map(|p| cmd_finder.must_have(p))
         .or_else(|| cmd_finder.maybe_have("gdb"));
 
+    build.config.reuse = build
+        .config
+        .reuse
+        .take()
+        .map(|p| cmd_finder.must_have(p))
+        .or_else(|| cmd_finder.maybe_have("reuse"));
+
     // We're gonna build some custom C code here and there, host triples
     // also build some C++ shims for LLVM so we need a C++ compiler.
     for target in &build.targets {
@@ -155,7 +162,15 @@ than building it.
             continue;
         }
 
-        if !build.config.dry_run {
+        // Some environments don't want or need these tools, such as when testing Miri.
+        // FIXME: it would be better to refactor this code to split necessary setup from pure sanity
+        // checks, and have a regular flag for skipping the latter. Also see
+        // <https://github.com/rust-lang/rust/pull/103569#discussion_r1008741742>.
+        if env::var_os("BOOTSTRAP_SKIP_TARGET_SANITY").is_some() {
+            continue;
+        }
+
+        if !build.config.dry_run() {
             cmd_finder.must_have(build.cc(*target));
             if let Some(ar) = build.ar(*target) {
                 cmd_finder.must_have(ar);
@@ -164,7 +179,7 @@ than building it.
     }
 
     for host in &build.hosts {
-        if !build.config.dry_run {
+        if !build.config.dry_run() {
             cmd_finder.must_have(build.cxx(*host).unwrap());
         }
     }
@@ -212,6 +227,14 @@ than building it.
             }
         }
 
+        // Some environments don't want or need these tools, such as when testing Miri.
+        // FIXME: it would be better to refactor this code to split necessary setup from pure sanity
+        // checks, and have a regular flag for skipping the latter. Also see
+        // <https://github.com/rust-lang/rust/pull/103569#discussion_r1008741742>.
+        if env::var_os("BOOTSTRAP_SKIP_TARGET_SANITY").is_some() {
+            continue;
+        }
+
         if need_cmake && target.contains("msvc") {
             // There are three builds of cmake on windows: MSVC, MinGW, and
             // Cygwin. The Cygwin build does not have generators for Visual
diff --git a/src/bootstrap/setup.rs b/src/bootstrap/setup.rs
index eb7da1bda..c7f98a7d0 100644
--- a/src/bootstrap/setup.rs
+++ b/src/bootstrap/setup.rs
@@ -1,15 +1,13 @@
+use crate::Config;
 use crate::{t, VERSION};
-use crate::{Config, TargetSelection};
 use std::env::consts::EXE_SUFFIX;
 use std::fmt::Write as _;
 use std::fs::File;
+use std::io::Write;
 use std::path::{Path, PathBuf, MAIN_SEPARATOR};
 use std::process::Command;
 use std::str::FromStr;
-use std::{
-    env, fmt, fs,
-    io::{self, Write},
-};
+use std::{fmt, fs, io};
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum Profile {
@@ -81,38 +79,10 @@ impl fmt::Display for Profile {
     }
 }
 
-pub fn setup(config: &Config, profile: Profile) {
-    let path = &config.config;
-
-    if path.exists() {
-        eprintln!(
-            "error: you asked `x.py` to setup a new config file, but one already exists at `{}`",
-            path.display()
-        );
-        eprintln!("help: try adding `profile = \"{}\"` at the top of {}", profile, path.display());
-        eprintln!(
-            "note: this will use the configuration in {}",
-            profile.include_path(&config.src).display()
-        );
-        crate::detail_exit(1);
-    }
-
-    let settings = format!(
-        "# Includes one of the default files in src/bootstrap/defaults\n\
-    profile = \"{}\"\n\
-    changelog-seen = {}\n",
-        profile, VERSION
-    );
-    t!(fs::write(path, settings));
-
-    let include_path = profile.include_path(&config.src);
-    println!("`x.py` will now use the configuration at {}", include_path.display());
-
-    let build = TargetSelection::from_user(&env!("BUILD_TRIPLE"));
+pub fn setup(config: &Config, profile: Option<Profile>) {
+    let profile = profile.unwrap_or_else(|| t!(interactive_path()));
     let stage_path =
-        ["build", build.rustc_target_arg(), "stage1"].join(&MAIN_SEPARATOR.to_string());
-
-    println!();
+        ["build", config.build.rustc_target_arg(), "stage1"].join(&MAIN_SEPARATOR.to_string());
 
     if !rustup_installed() && profile != Profile::User {
         eprintln!("`rustup` is not installed; cannot link `stage1` toolchain");
@@ -134,8 +104,6 @@ pub fn setup(config: &Config, profile: Profile) {
         Profile::User => &["dist", "build"],
     };
 
-    println!();
-
     t!(install_git_hook_maybe(&config));
 
     println!();
@@ -150,6 +118,36 @@ pub fn setup(config: &Config, profile: Profile) {
             "For more suggestions, see https://rustc-dev-guide.rust-lang.org/building/suggested.html"
         );
     }
+
+    let path = &config.config.clone().unwrap_or(PathBuf::from("config.toml"));
+    setup_config_toml(path, profile, config);
+}
+
+fn setup_config_toml(path: &PathBuf, profile: Profile, config: &Config) {
+    if path.exists() {
+        eprintln!();
+        eprintln!(
+            "error: you asked `x.py` to setup a new config file, but one already exists at `{}`",
+            path.display()
+        );
+        eprintln!("help: try adding `profile = \"{}\"` at the top of {}", profile, path.display());
+        eprintln!(
+            "note: this will use the configuration in {}",
+            profile.include_path(&config.src).display()
+        );
+        crate::detail_exit(1);
+    }
+
+    let settings = format!(
+        "# Includes one of the default files in src/bootstrap/defaults\n\
+    profile = \"{}\"\n\
+    changelog-seen = {}\n",
+        profile, VERSION
+    );
+    t!(fs::write(path, settings));
+
+    let include_path = profile.include_path(&config.src);
+    println!("`x.py` will now use the configuration at {}", include_path.display());
 }
 
 fn rustup_installed() -> bool {
@@ -303,7 +301,18 @@ pub fn interactive_path() -> io::Result<Profile> {
 
 // install a git hook to automatically run tidy --bless, if they want
 fn install_git_hook_maybe(config: &Config) -> io::Result<()> {
+    let git = t!(config.git().args(&["rev-parse", "--git-common-dir"]).output().map(|output| {
+        assert!(output.status.success(), "failed to run `git`");
+        PathBuf::from(t!(String::from_utf8(output.stdout)).trim())
+    }));
+    let dst = git.join("hooks").join("pre-push");
+    if dst.exists() {
+        // The git hook has already been set up, or the user already has a custom hook.
+        return Ok(());
+    }
+
     let mut input = String::new();
+    println!();
     println!(
         "Rust's CI will automatically fail if it doesn't pass `tidy`, the internal tool for ensuring code quality.
 If you'd like, x.py can install a git hook for you that will automatically run `tidy --bless` before
@@ -329,12 +338,6 @@ undesirable, simply delete the `pre-push` file from .git/hooks."
 
     if should_install {
         let src = config.src.join("src").join("etc").join("pre-push.sh");
-        let git =
-            t!(config.git().args(&["rev-parse", "--git-common-dir"]).output().map(|output| {
-                assert!(output.status.success(), "failed to run `git`");
-                PathBuf::from(t!(String::from_utf8(output.stdout)).trim())
-            }));
-        let dst = git.join("hooks").join("pre-push");
         match fs::hard_link(src, &dst) {
             Err(e) => eprintln!(
                 "error: could not create hook {}: do you already have the git hook installed?\n{}",
diff --git a/src/bootstrap/tarball.rs b/src/bootstrap/tarball.rs
index d999b6c15..fc850a22b 100644
--- a/src/bootstrap/tarball.rs
+++ b/src/bootstrap/tarball.rs
@@ -298,7 +298,7 @@ impl<'a> Tarball<'a> {
     fn run(self, build_cli: impl FnOnce(&Tarball<'a>, &mut Command)) -> GeneratedTarball {
         t!(std::fs::create_dir_all(&self.overlay_dir));
         self.builder.create(&self.overlay_dir.join("version"), &self.overlay.version(self.builder));
-        if let Some(info) = self.builder.rust_info.info() {
+        if let Some(info) = self.builder.rust_info().info() {
             channel::write_commit_hash_file(&self.overlay_dir, &info.sha);
             channel::write_commit_info_file(&self.overlay_dir, info);
         }
@@ -323,7 +323,7 @@ impl<'a> Tarball<'a> {
         // Ensure there are no symbolic links in the tarball. In particular,
         // rustup-toolchain-install-master and most versions of Windows can't handle symbolic links.
         let decompressed_output = self.temp_dir.join(&package_name);
-        if !self.builder.config.dry_run && !self.permit_symlinks {
+        if !self.builder.config.dry_run() && !self.permit_symlinks {
             for entry in walkdir::WalkDir::new(&decompressed_output) {
                 let entry = t!(entry);
                 if entry.path_is_symlink() {
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 791c35c36..39cedfdac 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -16,6 +16,7 @@ use crate::cache::Interned;
 use crate::compile;
 use crate::config::TargetSelection;
 use crate::dist;
+use crate::doc::DocumentationFormat;
 use crate::flags::Subcommand;
 use crate::native;
 use crate::tool::{self, SourceType, Tool};
@@ -90,6 +91,42 @@ fn try_run_quiet(builder: &Builder<'_>, cmd: &mut Command) -> bool {
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct CrateJsonDocLint {
+    host: TargetSelection,
+}
+
+impl Step for CrateJsonDocLint {
+    type Output = ();
+    const ONLY_HOSTS: bool = true;
+    const DEFAULT: bool = true;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/jsondoclint")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(CrateJsonDocLint { host: run.target });
+    }
+
+    fn run(self, builder: &Builder<'_>) {
+        let bootstrap_host = builder.config.build;
+        let compiler = builder.compiler(0, bootstrap_host);
+
+        let cargo = tool::prepare_tool_cargo(
+            builder,
+            compiler,
+            Mode::ToolBootstrap,
+            bootstrap_host,
+            "test",
+            "src/tools/jsondoclint",
+            SourceType::InTree,
+            &[],
+        );
+        try_run(builder, &mut cargo.into());
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Linkcheck {
     host: TargetSelection,
 }
@@ -464,52 +501,23 @@ pub struct Miri {
     target: TargetSelection,
 }
 
-impl Step for Miri {
-    type Output = ();
-    const ONLY_HOSTS: bool = false;
-
-    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.path("src/tools/miri")
-    }
-
-    fn make_run(run: RunConfig<'_>) {
-        run.builder.ensure(Miri {
-            stage: run.builder.top_stage,
-            host: run.build_triple(),
-            target: run.target,
-        });
-    }
-
-    /// Runs `cargo test` for miri.
-    fn run(self, builder: &Builder<'_>) {
-        let stage = self.stage;
-        let host = self.host;
-        let target = self.target;
-        let compiler = builder.compiler(stage, host);
-        // We need the stdlib for the *next* stage, as it was built with this compiler that also built Miri.
-        // Except if we are at stage 2, the bootstrap loop is complete and we can stick with our current stage.
-        let compiler_std = builder.compiler(if stage < 2 { stage + 1 } else { stage }, host);
-
-        let miri = builder
-            .ensure(tool::Miri { compiler, target: self.host, extra_features: Vec::new() })
-            .expect("in-tree tool");
-        let _cargo_miri = builder
-            .ensure(tool::CargoMiri { compiler, target: self.host, extra_features: Vec::new() })
-            .expect("in-tree tool");
-        // The stdlib we need might be at a different stage. And just asking for the
-        // sysroot does not seem to populate it, so we do that first.
-        builder.ensure(compile::Std::new(compiler_std, host));
-        let sysroot = builder.sysroot(compiler_std);
-
-        // # Run `cargo miri setup` for the given target.
+impl Miri {
+    /// Run `cargo miri setup` for the given target, return where the Miri sysroot was put.
+    pub fn build_miri_sysroot(
+        builder: &Builder<'_>,
+        compiler: Compiler,
+        miri: &Path,
+        target: TargetSelection,
+    ) -> String {
+        let miri_sysroot = builder.out.join(compiler.host.triple).join("miri-sysroot");
         let mut cargo = tool::prepare_tool_cargo(
             builder,
             compiler,
             Mode::ToolRustc,
-            host,
+            compiler.host,
             "run",
             "src/tools/miri/cargo-miri",
-            SourceType::Submodule,
+            SourceType::InTree,
             &[],
         );
         cargo.add_rustc_lib_path(builder, compiler);
@@ -520,6 +528,8 @@ impl Step for Miri {
         cargo.env("MIRI_LIB_SRC", builder.src.join("library"));
         // Tell it where to find Miri.
         cargo.env("MIRI", &miri);
+        // Tell it where to put the sysroot.
+        cargo.env("MIRI_SYSROOT", &miri_sysroot);
         // Debug things.
         cargo.env("RUST_BACKTRACE", "1");
 
@@ -534,7 +544,7 @@ impl Step for Miri {
         cargo.arg("--print-sysroot");
 
         // FIXME: Is there a way in which we can re-use the usual `run` helpers?
-        let miri_sysroot = if builder.config.dry_run {
+        if builder.config.dry_run() {
             String::new()
         } else {
             builder.verbose(&format!("running: {:?}", cargo));
@@ -547,7 +557,48 @@ impl Step for Miri {
             let sysroot = stdout.trim_end();
             builder.verbose(&format!("`cargo miri setup --print-sysroot` said: {:?}", sysroot));
             sysroot.to_owned()
-        };
+        }
+    }
+}
+
+impl Step for Miri {
+    type Output = ();
+    const ONLY_HOSTS: bool = false;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("src/tools/miri")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(Miri {
+            stage: run.builder.top_stage,
+            host: run.build_triple(),
+            target: run.target,
+        });
+    }
+
+    /// Runs `cargo test` for miri.
+    fn run(self, builder: &Builder<'_>) {
+        let stage = self.stage;
+        let host = self.host;
+        let target = self.target;
+        let compiler = builder.compiler(stage, host);
+        // We need the stdlib for the *next* stage, as it was built with this compiler that also built Miri.
+        // Except if we are at stage 2, the bootstrap loop is complete and we can stick with our current stage.
+        let compiler_std = builder.compiler(if stage < 2 { stage + 1 } else { stage }, host);
+
+        let miri = builder
+            .ensure(tool::Miri { compiler, target: self.host, extra_features: Vec::new() })
+            .expect("in-tree tool");
+        let _cargo_miri = builder
+            .ensure(tool::CargoMiri { compiler, target: self.host, extra_features: Vec::new() })
+            .expect("in-tree tool");
+        // The stdlib we need might be at a different stage. And just asking for the
+        // sysroot does not seem to populate it, so we do that first.
+        builder.ensure(compile::Std::new(compiler_std, host));
+        let sysroot = builder.sysroot(compiler_std);
+        // We also need a Miri sysroot.
+        let miri_sysroot = Miri::build_miri_sysroot(builder, compiler, &miri, target);
 
         // # Run `cargo test`.
         let mut cargo = tool::prepare_tool_cargo(
@@ -557,7 +608,7 @@ impl Step for Miri {
             host,
             "test",
             "src/tools/miri",
-            SourceType::Submodule,
+            SourceType::InTree,
             &[],
         );
         cargo.add_rustc_lib_path(builder, compiler);
@@ -565,7 +616,6 @@ impl Step for Miri {
         // miri tests need to know about the stage sysroot
         cargo.env("MIRI_SYSROOT", &miri_sysroot);
         cargo.env("MIRI_HOST_SYSROOT", sysroot);
-        cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(compiler));
         cargo.env("MIRI", &miri);
         // propagate --bless
         if builder.config.cmd.bless() {
@@ -606,7 +656,6 @@ impl Step for Miri {
         // Tell `cargo miri` where to find things.
         cargo.env("MIRI_SYSROOT", &miri_sysroot);
         cargo.env("MIRI_HOST_SYSROOT", sysroot);
-        cargo.env("RUSTC_LIB_PATH", builder.rustc_libdir(compiler));
         cargo.env("MIRI", &miri);
         // Debug things.
         cargo.env("RUST_BACKTRACE", "1");
@@ -771,7 +820,10 @@ impl Step for RustdocTheme {
             cmd.env("RUSTDOC_LINKER", linker);
         }
         if builder.is_fuse_ld_lld(self.compiler.host) {
-            cmd.env("RUSTDOC_FUSE_LD_LLD", "1");
+            cmd.env(
+                "RUSTDOC_LLD_NO_THREADS",
+                util::lld_flag_no_threads(self.compiler.host.contains("windows")),
+            );
         }
         try_run(builder, &mut cmd);
     }
@@ -819,7 +871,11 @@ impl Step for RustdocJSStd {
                     command.arg("--test-file").arg(path);
                 }
             }
-            builder.ensure(crate::doc::Std { target: self.target, stage: builder.top_stage });
+            builder.ensure(crate::doc::Std {
+                target: self.target,
+                stage: builder.top_stage,
+                format: DocumentationFormat::HTML,
+            });
             builder.run(&mut command);
         } else {
             builder.info("No nodejs found, skipping \"src/test/rustdoc-js-std\" tests");
@@ -991,6 +1047,8 @@ impl Step for RustdocGUI {
                 //        instead of hard-coding this test
                 if entry.file_name() == "link_to_definition" {
                     cargo.env("RUSTDOCFLAGS", "-Zunstable-options --generate-link-to-definition");
+                } else if entry.file_name() == "scrape_examples" {
+                    cargo.arg("-Zrustdoc-scrape-examples=examples");
                 }
                 builder.run(&mut cargo);
             }
@@ -1049,6 +1107,9 @@ impl Step for Tidy {
         if builder.is_verbose() {
             cmd.arg("--verbose");
         }
+        if builder.config.cmd.bless() {
+            cmd.arg("--bless");
+        }
 
         builder.info("tidy check");
         try_run(builder, &mut cmd);
@@ -1378,6 +1439,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
 
         cmd.arg("--src-base").arg(builder.src.join("src/test").join(suite));
         cmd.arg("--build-base").arg(testdir(builder, compiler.host).join(suite));
+        cmd.arg("--sysroot-base").arg(builder.sysroot(compiler));
         cmd.arg("--stage-id").arg(format!("stage{}-{}", compiler.stage, target));
         cmd.arg("--suite").arg(suite);
         cmd.arg("--mode").arg(mode);
@@ -1514,7 +1576,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
         let mut copts_passed = false;
         if builder.config.llvm_enabled() {
             let llvm_config = builder.ensure(native::Llvm { target: builder.config.build });
-            if !builder.config.dry_run {
+            if !builder.config.dry_run() {
                 let llvm_version = output(Command::new(&llvm_config).arg("--version"));
                 let llvm_components = output(Command::new(&llvm_config).arg("--components"));
                 // Remove trailing newline from llvm-config output.
@@ -1532,14 +1594,14 @@ note: if you're sure you want to do this, please open an issue as to why. In the
             // requirement, but the `-L` library path is not propagated across
             // separate compilations. We can add LLVM's library path to the
             // platform-specific environment variable as a workaround.
-            if !builder.config.dry_run && suite.ends_with("fulldeps") {
+            if !builder.config.dry_run() && suite.ends_with("fulldeps") {
                 let llvm_libdir = output(Command::new(&llvm_config).arg("--libdir"));
                 add_link_lib_path(vec![llvm_libdir.trim().into()], &mut cmd);
             }
 
             // Only pass correct values for these flags for the `run-make` suite as it
             // requires that a C++ compiler was configured which isn't always the case.
-            if !builder.config.dry_run && matches!(suite, "run-make" | "run-make-fulldeps") {
+            if !builder.config.dry_run() && matches!(suite, "run-make" | "run-make-fulldeps") {
                 // The llvm/bin directory contains many useful cross-platform
                 // tools. Pass the path to run-make tests so they can use them.
                 let llvm_bin_path = llvm_config
@@ -1567,7 +1629,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
 
         // Only pass correct values for these flags for the `run-make` suite as it
         // requires that a C++ compiler was configured which isn't always the case.
-        if !builder.config.dry_run && matches!(suite, "run-make" | "run-make-fulldeps") {
+        if !builder.config.dry_run() && matches!(suite, "run-make" | "run-make-fulldeps") {
             cmd.arg("--cc")
                 .arg(builder.cc(target))
                 .arg("--cxx")
@@ -1647,6 +1709,10 @@ note: if you're sure you want to do this, please open an issue as to why. In the
 
         cmd.arg("--channel").arg(&builder.config.channel);
 
+        if let Some(commit) = builder.config.download_rustc_commit() {
+            cmd.env("FAKE_DOWNLOAD_RUSTC_PREFIX", format!("/rustc/{commit}"));
+        }
+
         builder.ci_env.force_coloring_in_ci(&mut cmd);
 
         builder.info(&format!(
diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs
index eec74b267..e0be4c432 100644
--- a/src/bootstrap/tool.rs
+++ b/src/bootstrap/tool.rs
@@ -380,6 +380,8 @@ bootstrap_tool!(
     HtmlChecker, "src/tools/html-checker", "html-checker";
     BumpStage0, "src/tools/bump-stage0", "bump-stage0";
     ReplaceVersionPlaceholder, "src/tools/replace-version-placeholder", "replace-version-placeholder";
+    CollectLicenseMetadata, "src/tools/collect-license-metadata", "collect-license-metadata";
+    GenerateCopyright, "src/tools/generate-copyright", "generate-copyright";
 );
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
@@ -522,7 +524,7 @@ impl Step for Rustdoc {
         builder.ensure(compile::Rustc::new(build_compiler, target_compiler.host));
         // NOTE: this implies that `download-rustc` is pretty useless when compiling with the stage0
         // compiler, since you do just as much work.
-        if !builder.config.dry_run && builder.download_rustc() && build_compiler.stage == 0 {
+        if !builder.config.dry_run() && builder.download_rustc() && build_compiler.stage == 0 {
             println!(
                 "warning: `download-rustc` does nothing when building stage1 tools; consider using `--stage 2` instead"
             );
@@ -794,10 +796,9 @@ macro_rules! tool_extended {
        $($name:ident,
        $path:expr,
        $tool_name:expr,
-       stable = $stable:expr,
-       $(in_tree = $in_tree:expr,)?
-       $(tool_std = $tool_std:literal,)?
-       $extra_deps:block;)+) => {
+       stable = $stable:expr
+       $(,tool_std = $tool_std:literal)?
+       ;)+) => {
         $(
             #[derive(Debug, Clone, Hash, PartialEq, Eq)]
         pub struct $name {
@@ -839,7 +840,6 @@ macro_rules! tool_extended {
 
             #[allow(unused_mut)]
             fn run(mut $sel, $builder: &Builder<'_>) -> Option<PathBuf> {
-                $extra_deps
                 $builder.ensure(ToolBuild {
                     compiler: $sel.compiler,
                     target: $sel.target,
@@ -848,11 +848,7 @@ macro_rules! tool_extended {
                     path: $path,
                     extra_features: $sel.extra_features,
                     is_optional_tool: true,
-                    source_type: if false $(|| $in_tree)* {
-                        SourceType::InTree
-                    } else {
-                        SourceType::Submodule
-                    },
+                    source_type: SourceType::InTree,
                 })
             }
         }
@@ -865,17 +861,17 @@ macro_rules! tool_extended {
 // Note: Most submodule updates for tools are handled by bootstrap.py, since they're needed just to
 // invoke Cargo to build bootstrap. See the comment there for more details.
 tool_extended!((self, builder),
-    Cargofmt, "src/tools/rustfmt", "cargo-fmt", stable=true, in_tree=true, {};
-    CargoClippy, "src/tools/clippy", "cargo-clippy", stable=true, in_tree=true, {};
-    Clippy, "src/tools/clippy", "clippy-driver", stable=true, in_tree=true, {};
-    Miri, "src/tools/miri", "miri", stable=false, in_tree=true, {};
-    CargoMiri, "src/tools/miri/cargo-miri", "cargo-miri", stable=false, in_tree=true, {};
+    Cargofmt, "src/tools/rustfmt", "cargo-fmt", stable=true;
+    CargoClippy, "src/tools/clippy", "cargo-clippy", stable=true;
+    Clippy, "src/tools/clippy", "clippy-driver", stable=true;
+    Miri, "src/tools/miri", "miri", stable=false;
+    CargoMiri, "src/tools/miri/cargo-miri", "cargo-miri", stable=true;
     // FIXME: tool_std is not quite right, we shouldn't allow nightly features.
     // But `builder.cargo` doesn't know how to handle ToolBootstrap in stages other than 0,
     // and this is close enough for now.
-    Rls, "src/tools/rls", "rls", stable=true, in_tree=true, tool_std=true, {};
-    RustDemangler, "src/tools/rust-demangler", "rust-demangler", stable=false, in_tree=true, tool_std=true, {};
-    Rustfmt, "src/tools/rustfmt", "rustfmt", stable=true, in_tree=true, {};
+    Rls, "src/tools/rls", "rls", stable=true, tool_std=true;
+    RustDemangler, "src/tools/rust-demangler", "rust-demangler", stable=false, tool_std=true;
+    Rustfmt, "src/tools/rustfmt", "rustfmt", stable=true;
 );
 
 impl<'a> Builder<'a> {
diff --git a/src/bootstrap/toolstate.rs b/src/bootstrap/toolstate.rs
index 1a1774432..1969e0b6f 100644
--- a/src/bootstrap/toolstate.rs
+++ b/src/bootstrap/toolstate.rs
@@ -158,7 +158,7 @@ impl Step for ToolStateCheck {
     ///   stable tool. That is, the status is not allowed to get worse
     ///   (test-pass to test-fail or build-fail).
     fn run(self, builder: &Builder<'_>) {
-        if builder.config.dry_run {
+        if builder.config.dry_run() {
             return;
         }
 
@@ -265,7 +265,7 @@ impl Builder<'_> {
         // If we're in a dry run setting we don't want to save toolstates as
         // that means if we e.g. panic down the line it'll look like we tested
         // everything (but we actually haven't).
-        if self.config.dry_run {
+        if self.config.dry_run() {
             return;
         }
         // Toolstate isn't tracked for clippy or rustfmt, but since most tools do, we avoid checking
diff --git a/src/bootstrap/util.rs b/src/bootstrap/util.rs
index 0ebabbd5c..582207832 100644
--- a/src/bootstrap/util.rs
+++ b/src/bootstrap/util.rs
@@ -13,6 +13,7 @@ use std::time::{Instant, SystemTime, UNIX_EPOCH};
 
 use crate::builder::Builder;
 use crate::config::{Config, TargetSelection};
+use crate::OnceCell;
 
 /// A helper macro to `unwrap` a result except also print out details like:
 ///
@@ -43,7 +44,13 @@ pub use t;
 /// Given an executable called `name`, return the filename for the
 /// executable for a particular target.
 pub fn exe(name: &str, target: TargetSelection) -> String {
-    if target.contains("windows") { format!("{}.exe", name) } else { name.to_string() }
+    if target.contains("windows") {
+        format!("{}.exe", name)
+    } else if target.contains("uefi") {
+        format!("{}.efi", name)
+    } else {
+        name.to_string()
+    }
 }
 
 /// Returns `true` if the file name given looks like a dynamic library.
@@ -104,7 +111,7 @@ pub struct TimeIt(bool, Instant);
 
 /// Returns an RAII structure that prints out how long it took to drop.
 pub fn timeit(builder: &Builder<'_>) -> TimeIt {
-    TimeIt(builder.config.dry_run, Instant::now())
+    TimeIt(builder.config.dry_run(), Instant::now())
 }
 
 impl Drop for TimeIt {
@@ -127,7 +134,7 @@ pub(crate) fn program_out_of_date(stamp: &Path, key: &str) -> bool {
 /// Symlinks two directories, using junctions on Windows and normal symlinks on
 /// Unix.
 pub fn symlink_dir(config: &Config, src: &Path, dest: &Path) -> io::Result<()> {
-    if config.dry_run {
+    if config.dry_run() {
         return Ok(());
     }
     let _ = fs::remove_dir(dest);
@@ -607,3 +614,16 @@ pub fn get_clang_cl_resource_dir(clang_cl_path: &str) -> PathBuf {
     let clang_rt_dir = clang_rt_builtins.parent().expect("The clang lib folder should exist");
     clang_rt_dir.to_path_buf()
 }
+
+pub fn lld_flag_no_threads(is_windows: bool) -> &'static str {
+    static LLD_NO_THREADS: OnceCell<(&'static str, &'static str)> = OnceCell::new();
+    let (windows, other) = LLD_NO_THREADS.get_or_init(|| {
+        let out = output(Command::new("lld").arg("-flavor").arg("ld").arg("--version"));
+        let newer = match (out.find(char::is_numeric), out.find('.')) {
+            (Some(b), Some(e)) => out.as_str()[b..e].parse::<i32>().ok().unwrap_or(14) > 10,
+            _ => true,
+        };
+        if newer { ("/threads:1", "--threads=1") } else { ("/no-threads", "--no-threads") }
+    });
+    if is_windows { windows } else { other }
+}