diff --git a/.gitignore b/.gitignore
index 87d02563ed0..aabec0988a9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,6 +48,7 @@ build/
 /dist/
 /unicode-downloads
 /target
+/library/target
 /src/bootstrap/target
 /src/tools/x/target
 # Created by default with `src/ci/docker/run.sh`
diff --git a/Cargo.lock b/Cargo.lock
index 1a7d7e3f5d7..b47a21355db 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,27 +11,11 @@ dependencies = [
  "gimli 0.28.1",
 ]
 
-[[package]]
-name = "addr2line"
-version = "0.22.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6e4503c46a5c0c7844e948c9a4d6acd9f50cccb4de1c48eb9e291ea17470c678"
-dependencies = [
- "compiler_builtins",
- "gimli 0.29.0",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "adler"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "aes"
@@ -66,16 +50,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "alloc"
-version = "0.0.0"
-dependencies = [
- "compiler_builtins",
- "core",
- "rand",
- "rand_xorshift",
-]
-
 [[package]]
 name = "allocator-api2"
 version = "0.2.18"
@@ -256,7 +230,7 @@ version = "0.3.71"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26b05800d2e817c8b3b4b54abd461726265fa9789ae34330622f2db9ee696f9d"
 dependencies = [
- "addr2line 0.21.0",
+ "addr2line",
  "cc",
  "cfg-if",
  "libc",
@@ -455,10 +429,6 @@ name = "cfg-if"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "cfg_aliases"
@@ -737,16 +707,6 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "55b672471b4e9f9e95499ea597ff64941a309b2cdbffcc46f2cc5e2d971fd335"
 
-[[package]]
-name = "compiler_builtins"
-version = "0.1.114"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eb58b199190fcfe0846f55a3b545cd6b07a34bdd5930a476ff856f3ebcc5558a"
-dependencies = [
- "cc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "compiletest"
 version = "0.0.0"
@@ -787,14 +747,6 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
-[[package]]
-name = "core"
-version = "0.0.0"
-dependencies = [
- "rand",
- "rand_xorshift",
-]
-
 [[package]]
 name = "core-foundation-sys"
 version = "0.8.6"
@@ -1134,19 +1086,6 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "59f8e79d1fbf76bdfbde321e902714bf6c49df88a7dda6fc682fc2979226962d"
 
-[[package]]
-name = "dlmalloc"
-version = "0.2.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3264b043b8e977326c1ee9e723da2c1f8d09a99df52cacf00b4dbce5ac54414d"
-dependencies = [
- "cfg-if",
- "compiler_builtins",
- "libc",
- "rustc-std-workspace-core",
- "windows-sys 0.52.0",
-]
-
 [[package]]
 name = "either"
 version = "1.12.0"
@@ -1348,16 +1287,6 @@ dependencies = [
  "percent-encoding",
 ]
 
-[[package]]
-name = "fortanix-sgx-abi"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57cafc2274c10fab234f176b25903ce17e690fca7597090d50880e047a0389c5"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "fs-err"
 version = "2.11.0"
@@ -1504,8 +1433,6 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "14dbbfd5c71d70241ecf9e6f13737f7b5ce823821063188d7e46c41d371eebd5"
 dependencies = [
- "rustc-std-workspace-core",
- "rustc-std-workspace-std",
  "unicode-width",
 ]
 
@@ -1526,25 +1453,11 @@ version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4271d37baee1b8c7e4b708028c57d816cf9d2434acb33a549475f78c181f6253"
 dependencies = [
- "compiler_builtins",
  "fallible-iterator",
  "indexmap",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
  "stable_deref_trait",
 ]
 
-[[package]]
-name = "gimli"
-version = "0.29.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "gimli"
 version = "0.31.0"
@@ -1606,9 +1519,6 @@ checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
 dependencies = [
  "ahash",
  "allocator-api2",
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
  "serde",
 ]
 
@@ -1630,17 +1540,6 @@ version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 
-[[package]]
-name = "hermit-abi"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "hex"
 version = "0.4.3"
@@ -2065,9 +1964,6 @@ name = "libc"
 version = "0.2.155"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
-dependencies = [
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "libdbus-sys"
@@ -2299,10 +2195,6 @@ name = "memchr"
 version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "memmap2"
@@ -2357,9 +2249,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8a240ddb74feaf34a79a7add65a741f3167852fba007066dcac1ca548d89c08"
 dependencies = [
  "adler",
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
 ]
 
 [[package]]
@@ -2549,7 +2438,7 @@ version = "1.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4161fcb6d602d4d2081af7c3a45852d875a03dd337a6bfdd6e06407b61342a43"
 dependencies = [
- "hermit-abi 0.3.9",
+ "hermit-abi",
  "libc",
 ]
 
@@ -2588,14 +2477,11 @@ version = "0.36.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f203fa8daa7bb185f760ae12bd8e097f63d17041dcdcaf675ac54cdf863170e"
 dependencies = [
- "compiler_builtins",
  "crc32fast",
  "flate2",
  "hashbrown",
  "indexmap",
  "memchr",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
  "ruzstd 0.7.0",
  "wasmparser 0.214.0",
 ]
@@ -2719,29 +2605,6 @@ dependencies = [
  "unicode-width",
 ]
 
-[[package]]
-name = "panic_abort"
-version = "0.0.0"
-dependencies = [
- "alloc",
- "cfg-if",
- "compiler_builtins",
- "core",
- "libc",
-]
-
-[[package]]
-name = "panic_unwind"
-version = "0.0.0"
-dependencies = [
- "alloc",
- "cfg-if",
- "compiler_builtins",
- "core",
- "libc",
- "unwind",
-]
-
 [[package]]
 name = "papergrid"
 version = "0.11.0"
@@ -2996,23 +2859,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "proc_macro"
-version = "0.0.0"
-dependencies = [
- "core",
- "std",
-]
-
-[[package]]
-name = "profiler_builtins"
-version = "0.0.0"
-dependencies = [
- "cc",
- "compiler_builtins",
- "core",
-]
-
 [[package]]
 name = "psm"
 version = "0.1.21"
@@ -3090,27 +2936,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "r-efi"
-version = "4.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e9e935efc5854715dfc0a4c9ef18dc69dee0ec3bf9cc3ab740db831c0fdd86a3"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
-
-[[package]]
-name = "r-efi-alloc"
-version = "1.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "31d6f09fe2b6ad044bc3d2c34ce4979796581afd2f1ebc185837e02421e02fd7"
-dependencies = [
- "compiler_builtins",
- "r-efi",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "rand"
 version = "0.8.5"
@@ -3141,15 +2966,6 @@ dependencies = [
  "getrandom",
 ]
 
-[[package]]
-name = "rand_xorshift"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d25bf25ec5ae4a3f1b92f929810509a2f53d7dca2f50b794ff57e3face536c8f"
-dependencies = [
- "rand_core",
-]
-
 [[package]]
 name = "rand_xoshiro"
 version = "0.6.0"
@@ -3361,10 +3177,6 @@ name = "rustc-demangle"
 version = "0.1.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "719b953e2095829ee67db738b3bfa9fa368c94900df327b3f07fe6e794d2fe1f"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "rustc-hash"
@@ -3425,27 +3237,6 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5c9f15eec8235d7cb775ee6f81891db79b98fd54ba1ad8fae565b88ef1ae4e2"
 
-[[package]]
-name = "rustc-std-workspace-alloc"
-version = "1.99.0"
-dependencies = [
- "alloc",
-]
-
-[[package]]
-name = "rustc-std-workspace-core"
-version = "1.99.0"
-dependencies = [
- "core",
-]
-
-[[package]]
-name = "rustc-std-workspace-std"
-version = "1.99.0"
-dependencies = [
- "std",
-]
-
 [[package]]
 name = "rustc_abi"
 version = "0.0.0"
@@ -5231,46 +5022,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
-[[package]]
-name = "std"
-version = "0.0.0"
-dependencies = [
- "addr2line 0.22.0",
- "alloc",
- "cfg-if",
- "compiler_builtins",
- "core",
- "dlmalloc",
- "fortanix-sgx-abi",
- "hashbrown",
- "hermit-abi 0.4.0",
- "libc",
- "miniz_oxide",
- "object 0.36.2",
- "panic_abort",
- "panic_unwind",
- "profiler_builtins",
- "r-efi",
- "r-efi-alloc",
- "rand",
- "rand_xorshift",
- "rustc-demangle",
- "std_detect",
- "unwind",
- "wasi",
-]
-
-[[package]]
-name = "std_detect"
-version = "0.1.5"
-dependencies = [
- "cfg-if",
- "compiler_builtins",
- "libc",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "string_cache"
 version = "0.8.7"
@@ -5377,15 +5128,6 @@ dependencies = [
  "windows",
 ]
 
-[[package]]
-name = "sysroot"
-version = "0.0.0"
-dependencies = [
- "proc_macro",
- "std",
- "test",
-]
-
 [[package]]
 name = "tabled"
 version = "0.15.0"
@@ -5470,16 +5212,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "test"
-version = "0.0.0"
-dependencies = [
- "core",
- "getopts",
- "libc",
- "std",
-]
-
 [[package]]
 name = "test-float-parse"
 version = "0.1.0"
@@ -5978,11 +5710,6 @@ name = "unicode-width"
 version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0336d538f7abc86d282a4189614dfaa90810dfc2c6f6427eaf88e16311dd225d"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-core",
- "rustc-std-workspace-std",
-]
 
 [[package]]
 name = "unicode-xid"
@@ -6007,28 +5734,6 @@ dependencies = [
  "tidy",
 ]
 
-[[package]]
-name = "unwind"
-version = "0.0.0"
-dependencies = [
- "cfg-if",
- "compiler_builtins",
- "core",
- "libc",
- "unwinding",
-]
-
-[[package]]
-name = "unwinding"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "37a19a21a537f635c16c7576f22d0f2f7d63353c1337ad4ce0d8001c7952a25b"
-dependencies = [
- "compiler_builtins",
- "gimli 0.28.1",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "url"
 version = "2.5.2"
@@ -6100,11 +5805,6 @@ name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
 
 [[package]]
 name = "wasm-bindgen"
diff --git a/Cargo.toml b/Cargo.toml
index 178a5ab9408..131feec70ab 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,8 +2,6 @@
 resolver = "1"
 members = [
   "compiler/rustc",
-  "library/std",
-  "library/sysroot",
   "src/etc/test-float-parse",
   "src/rustdoc-json-types",
   "src/tools/build_helper",
@@ -61,23 +59,8 @@ exclude = [
   # not all `Cargo.toml` files are available, so we exclude the `x` binary,
   # so it can be invoked before the current checkout is set up.
   "src/tools/x",
-  # stdarch has its own Cargo workspace
-  "library/stdarch",
 ]
 
-[profile.release.package.compiler_builtins]
-# For compiler-builtins we always use a high number of codegen units.
-# The goal here is to place every single intrinsic into its own object
-# file to avoid symbol clashes with the system libgcc if possible. Note
-# that this number doesn't actually produce this many object files, we
-# just don't create more than this number of object files.
-#
-# It's a bit of a bummer that we have to pass this here, unfortunately.
-# Ideally this would be specified through an env var to Cargo so Cargo
-# knows how many CGUs are for this specific crate, but for now
-# per-crate configuration isn't specifiable in the environment.
-codegen-units = 10000
-
 [profile.release.package.rustc-rayon-core]
 # The rustc fork of Rayon has deadlock detection code which intermittently
 # causes overflows in the CI (see https://github.com/rust-lang/rust/issues/90227)
@@ -85,19 +68,6 @@ codegen-units = 10000
 # FIXME: This workaround should be removed once #90227 is fixed.
 overflow-checks = false
 
-# These dependencies of the standard library implement symbolication for
-# backtraces on most platforms. Their debuginfo causes both linking to be slower
-# (more data to chew through) and binaries to be larger without really all that
-# much benefit. This section turns them all to down to have no debuginfo which
-# helps to improve link times a little bit.
-[profile.release.package]
-addr2line.debug = 0
-adler.debug = 0
-gimli.debug = 0
-miniz_oxide.debug = 0
-object.debug = 0
-rustc-demangle.debug = 0
-
 # These are very thin wrappers around executing lld with the right binary name.
 # Basically nothing within them can go wrong without having been explicitly logged anyway.
 # We ship these in every rustc tarball and even after compression they add up
@@ -120,10 +90,3 @@ codegen-units = 1
 # FIXME: LTO cannot be enabled for binaries in a workspace
 # <https://github.com/rust-lang/cargo/issues/9330>
 # lto = true
-
-[patch.crates-io]
-# See comments in `library/rustc-std-workspace-core/README.md` for what's going on
-# here
-rustc-std-workspace-core = { path = 'library/rustc-std-workspace-core' }
-rustc-std-workspace-alloc = { path = 'library/rustc-std-workspace-alloc' }
-rustc-std-workspace-std = { path = 'library/rustc-std-workspace-std' }
diff --git a/library/Cargo.lock b/library/Cargo.lock
new file mode 100644
index 00000000000..223b61456c2
--- /dev/null
+++ b/library/Cargo.lock
@@ -0,0 +1,489 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "addr2line"
+version = "0.22.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e4503c46a5c0c7844e948c9a4d6acd9f50cccb4de1c48eb9e291ea17470c678"
+dependencies = [
+ "compiler_builtins",
+ "gimli 0.29.0",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "adler"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "alloc"
+version = "0.0.0"
+dependencies = [
+ "compiler_builtins",
+ "core",
+ "rand",
+ "rand_xorshift",
+]
+
+[[package]]
+name = "allocator-api2"
+version = "0.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c6cb57a04249c6480766f7f7cef5467412af1490f8d1e243141daddada3264f"
+
+[[package]]
+name = "cc"
+version = "1.0.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96c51067fd44124faa7f870b4b1c969379ad32b2ba805aa959430ceaa384f695"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "compiler_builtins"
+version = "0.1.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb58b199190fcfe0846f55a3b545cd6b07a34bdd5930a476ff856f3ebcc5558a"
+dependencies = [
+ "cc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "core"
+version = "0.0.0"
+dependencies = [
+ "rand",
+ "rand_xorshift",
+]
+
+[[package]]
+name = "dlmalloc"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3264b043b8e977326c1ee9e723da2c1f8d09a99df52cacf00b4dbce5ac54414d"
+dependencies = [
+ "cfg-if",
+ "compiler_builtins",
+ "libc",
+ "rustc-std-workspace-core",
+ "windows-sys",
+]
+
+[[package]]
+name = "fortanix-sgx-abi"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57cafc2274c10fab234f176b25903ce17e690fca7597090d50880e047a0389c5"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "getopts"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14dbbfd5c71d70241ecf9e6f13737f7b5ce823821063188d7e46c41d371eebd5"
+dependencies = [
+ "rustc-std-workspace-core",
+ "rustc-std-workspace-std",
+ "unicode-width",
+]
+
+[[package]]
+name = "gimli"
+version = "0.28.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4271d37baee1b8c7e4b708028c57d816cf9d2434acb33a549475f78c181f6253"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "gimli"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+dependencies = [
+ "allocator-api2",
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "hermit-abi"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+dependencies = [
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "memchr"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "miniz_oxide"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8a240ddb74feaf34a79a7add65a741f3167852fba007066dcac1ca548d89c08"
+dependencies = [
+ "adler",
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "object"
+version = "0.36.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f203fa8daa7bb185f760ae12bd8e097f63d17041dcdcaf675ac54cdf863170e"
+dependencies = [
+ "compiler_builtins",
+ "memchr",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "panic_abort"
+version = "0.0.0"
+dependencies = [
+ "alloc",
+ "cfg-if",
+ "compiler_builtins",
+ "core",
+ "libc",
+]
+
+[[package]]
+name = "panic_unwind"
+version = "0.0.0"
+dependencies = [
+ "alloc",
+ "cfg-if",
+ "compiler_builtins",
+ "core",
+ "libc",
+ "unwind",
+]
+
+[[package]]
+name = "proc_macro"
+version = "0.0.0"
+dependencies = [
+ "core",
+ "std",
+]
+
+[[package]]
+name = "profiler_builtins"
+version = "0.0.0"
+dependencies = [
+ "cc",
+ "compiler_builtins",
+ "core",
+]
+
+[[package]]
+name = "r-efi"
+version = "4.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e9e935efc5854715dfc0a4c9ef18dc69dee0ec3bf9cc3ab740db831c0fdd86a3"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "r-efi-alloc"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "31d6f09fe2b6ad044bc3d2c34ce4979796581afd2f1ebc185837e02421e02fd7"
+dependencies = [
+ "compiler_builtins",
+ "r-efi",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+
+[[package]]
+name = "rand_xorshift"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d25bf25ec5ae4a3f1b92f929810509a2f53d7dca2f50b794ff57e3face536c8f"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
+name = "rustc-demangle"
+version = "0.1.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "719b953e2095829ee67db738b3bfa9fa368c94900df327b3f07fe6e794d2fe1f"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "rustc-std-workspace-alloc"
+version = "1.99.0"
+dependencies = [
+ "alloc",
+]
+
+[[package]]
+name = "rustc-std-workspace-core"
+version = "1.99.0"
+dependencies = [
+ "core",
+]
+
+[[package]]
+name = "rustc-std-workspace-std"
+version = "1.99.0"
+dependencies = [
+ "std",
+]
+
+[[package]]
+name = "std"
+version = "0.0.0"
+dependencies = [
+ "addr2line",
+ "alloc",
+ "cfg-if",
+ "compiler_builtins",
+ "core",
+ "dlmalloc",
+ "fortanix-sgx-abi",
+ "hashbrown",
+ "hermit-abi",
+ "libc",
+ "miniz_oxide",
+ "object",
+ "panic_abort",
+ "panic_unwind",
+ "profiler_builtins",
+ "r-efi",
+ "r-efi-alloc",
+ "rand",
+ "rand_xorshift",
+ "rustc-demangle",
+ "std_detect",
+ "unwind",
+ "wasi",
+]
+
+[[package]]
+name = "std_detect"
+version = "0.1.5"
+dependencies = [
+ "cfg-if",
+ "compiler_builtins",
+ "libc",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "sysroot"
+version = "0.0.0"
+dependencies = [
+ "proc_macro",
+ "std",
+ "test",
+]
+
+[[package]]
+name = "test"
+version = "0.0.0"
+dependencies = [
+ "core",
+ "getopts",
+ "libc",
+ "std",
+]
+
+[[package]]
+name = "unicode-width"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0336d538f7abc86d282a4189614dfaa90810dfc2c6f6427eaf88e16311dd225d"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+ "rustc-std-workspace-std",
+]
+
+[[package]]
+name = "unwind"
+version = "0.0.0"
+dependencies = [
+ "cfg-if",
+ "compiler_builtins",
+ "core",
+ "libc",
+ "unwinding",
+]
+
+[[package]]
+name = "unwinding"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37a19a21a537f635c16c7576f22d0f2f7d63353c1337ad4ce0d8001c7952a25b"
+dependencies = [
+ "compiler_builtins",
+ "gimli 0.28.1",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f0713a46559409d202e70e28227288446bf7841d3211583a4b53e3f6d96e7eb"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7088eed71e8b8dda258ecc8bac5fb1153c5cffaf2578fc8ff5d61e23578d3263"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9985fd1504e250c615ca5f281c3f7a6da76213ebd5ccc9561496568a2752afb6"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88ba073cf16d5372720ec942a8ccbf61626074c6d4dd2e745299726ce8b89670"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87f4261229030a858f36b459e748ae97545d6f1ec60e5e0d6a3d32e0dc232ee9"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db3c2bf3d13d5b658be73463284eaf12830ac9a26a90c717b7f771dfe97487bf"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e4246f76bdeff09eb48875a0fd3e2af6aada79d409d33011886d3e1581517d9"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "852298e482cd67c356ddd9570386e2862b5673c85bd5f88df9ab6802b334c596"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
diff --git a/library/Cargo.toml b/library/Cargo.toml
new file mode 100644
index 00000000000..c4513b4c127
--- /dev/null
+++ b/library/Cargo.toml
@@ -0,0 +1,44 @@
+[workspace]
+resolver = "1"
+members = [
+  "std",
+  "sysroot",
+]
+
+exclude = [
+  # stdarch has its own Cargo workspace
+  "stdarch",
+]
+
+[profile.release.package.compiler_builtins]
+# For compiler-builtins we always use a high number of codegen units.
+# The goal here is to place every single intrinsic into its own object
+# file to avoid symbol clashes with the system libgcc if possible. Note
+# that this number doesn't actually produce this many object files, we
+# just don't create more than this number of object files.
+#
+# It's a bit of a bummer that we have to pass this here, unfortunately.
+# Ideally this would be specified through an env var to Cargo so Cargo
+# knows how many CGUs are for this specific crate, but for now
+# per-crate configuration isn't specifiable in the environment.
+codegen-units = 10000
+
+# These dependencies of the standard library implement symbolication for
+# backtraces on most platforms. Their debuginfo causes both linking to be slower
+# (more data to chew through) and binaries to be larger without really all that
+# much benefit. This section turns them all to down to have no debuginfo which
+# helps to improve link times a little bit.
+[profile.release.package]
+addr2line.debug = 0
+adler.debug = 0
+gimli.debug = 0
+miniz_oxide.debug = 0
+object.debug = 0
+rustc-demangle.debug = 0
+
+[patch.crates-io]
+# See comments in `library/rustc-std-workspace-core/README.md` for what's going on
+# here
+rustc-std-workspace-core = { path = 'rustc-std-workspace-core' }
+rustc-std-workspace-alloc = { path = 'rustc-std-workspace-alloc' }
+rustc-std-workspace-std = { path = 'rustc-std-workspace-std' }
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index 58f86aa996d..c14709ffb63 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -1034,6 +1034,8 @@ fn run(self, builder: &Builder<'_>) -> GeneratedTarball {
                 .arg("--sync")
                 .arg(builder.src.join("./compiler/rustc_codegen_gcc/Cargo.toml"))
                 .arg("--sync")
+                .arg(builder.src.join("./library/Cargo.toml"))
+                .arg("--sync")
                 .arg(builder.src.join("./src/bootstrap/Cargo.toml"))
                 .arg("--sync")
                 .arg(builder.src.join("./src/tools/opt-dist/Cargo.toml"))
diff --git a/src/bootstrap/src/core/build_steps/vendor.rs b/src/bootstrap/src/core/build_steps/vendor.rs
index 81770036d71..33768465225 100644
--- a/src/bootstrap/src/core/build_steps/vendor.rs
+++ b/src/bootstrap/src/core/build_steps/vendor.rs
@@ -47,6 +47,7 @@ fn run(self, builder: &Builder<'_>) -> Self::Output {
             "src/tools/rust-analyzer/Cargo.toml",
             "compiler/rustc_codegen_cranelift/Cargo.toml",
             "compiler/rustc_codegen_gcc/Cargo.toml",
+            "library/Cargo.toml",
             "src/bootstrap/Cargo.toml",
             "src/tools/rustbook/Cargo.toml",
         ] {
diff --git a/src/bootstrap/src/core/metadata.rs b/src/bootstrap/src/core/metadata.rs
index 9b4c85e6d34..c11230744c3 100644
--- a/src/bootstrap/src/core/metadata.rs
+++ b/src/bootstrap/src/core/metadata.rs
@@ -87,5 +87,8 @@ fn workspace_members(build: &Build) -> Vec<Package> {
     };
 
     // Collects `metadata.packages` from all workspaces.
-    collect_metadata("Cargo.toml")
+    let mut packages = vec![];
+    packages.extend(collect_metadata("Cargo.toml"));
+    packages.extend(collect_metadata("library/Cargo.toml"));
+    packages
 }
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index de59d7d89f9..e23e931b0eb 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -54,6 +54,7 @@
 pub(crate) const WORKSPACES: &[(&str, ExceptionList, Option<(&[&str], &[&str])>, &[&str])] = &[
     // The root workspace has to be first for check_rustfix to work.
     (".", EXCEPTIONS, Some((&["rustc-main"], PERMITTED_RUSTC_DEPENDENCIES)), &[]),
+    ("library", EXCEPTIONS_STDLIB, Some((&["sysroot"], PERMITTED_STDLIB_DEPENDENCIES)), &[]),
     // Outside of the alphabetical section because rustfmt formats it using multiple lines.
     (
         "compiler/rustc_codegen_cranelift",
@@ -90,7 +91,6 @@
     ("colored", "MPL-2.0"),                                  // rustfmt
     ("dissimilar", "Apache-2.0"),                            // rustdoc, rustc_lexer (few tests) via expect-test, (dev deps)
     ("fluent-langneg", "Apache-2.0"),                        // rustc (fluent translations)
-    ("fortanix-sgx-abi", "MPL-2.0"),                         // libstd but only for `sgx` target. FIXME: this dependency violates the documentation comment above.
     ("instant", "BSD-3-Clause"),                             // rustc_driver/tracing-subscriber/parking_lot
     ("mdbook", "MPL-2.0"),                                   // mdbook
     ("option-ext", "MPL-2.0"),                               // cargo-miri (via `directories`)
@@ -108,6 +108,17 @@
     // tidy-alphabetical-end
 ];
 
+/// These are exceptions to Rust's permissive licensing policy, and
+/// should be considered bugs. Exceptions are only allowed in Rust
+/// tooling. It is _crucial_ that no exception crates be dependencies
+/// of the Rust runtime (std/test).
+#[rustfmt::skip]
+const EXCEPTIONS_STDLIB: ExceptionList = &[
+    // tidy-alphabetical-start
+    ("fortanix-sgx-abi", "MPL-2.0"), // libstd but only for `sgx` target. FIXME: this dependency violates the documentation comment above.
+    // tidy-alphabetical-end
+];
+
 // FIXME uncomment once rust-lang/stdarch#1462 lands
 /*
 const EXCEPTIONS_STDARCH: ExceptionList = &[
@@ -228,10 +239,6 @@
     "ring",
 ];
 
-/// These are the root crates that are part of the runtime. The licenses for
-/// these and all their dependencies *must not* be in the exception list.
-const RUNTIME_CRATES: &[&str] = &["std", "core", "alloc", "test", "panic_abort", "panic_unwind"];
-
 const PERMITTED_DEPS_LOCATION: &str = concat!(file!(), ":", line!());
 
 /// Crates rustc is allowed to depend on. Avoid adding to the list if possible.
@@ -240,7 +247,6 @@
 /// rustc. Please check with the compiler team before adding an entry.
 const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     // tidy-alphabetical-start
-    "addr2line",
     "adler",
     "ahash",
     "aho-corasick",
@@ -256,7 +262,6 @@
     "cc",
     "cfg-if",
     "cfg_aliases",
-    "compiler_builtins",
     "cpufeatures",
     "crc32fast",
     "crossbeam-channel",
@@ -276,7 +281,6 @@
     "digest",
     "displaydoc",
     "dissimilar",
-    "dlmalloc",
     "either",
     "elsa",
     "ena",
@@ -291,7 +295,6 @@
     "fluent-langneg",
     "fluent-syntax",
     "fnv",
-    "fortanix-sgx-abi",
     "generic-array",
     "getopts",
     "getrandom",
@@ -354,12 +357,9 @@
     "pulldown-cmark-escape",
     "punycode",
     "quote",
-    "r-efi",
-    "r-efi-alloc",
     "rand",
     "rand_chacha",
     "rand_core",
-    "rand_xorshift",
     "rand_xoshiro",
     "redox_syscall",
     "regex",
@@ -429,7 +429,6 @@
     "unicode-security",
     "unicode-width",
     "unicode-xid",
-    "unwinding",
     "valuable",
     "version_check",
     "wasi",
@@ -463,6 +462,46 @@
     // tidy-alphabetical-end
 ];
 
+const PERMITTED_STDLIB_DEPENDENCIES: &[&str] = &[
+    // tidy-alphabetical-start
+    "addr2line",
+    "adler",
+    "allocator-api2",
+    "cc",
+    "cfg-if",
+    "compiler_builtins",
+    "dlmalloc",
+    "fortanix-sgx-abi",
+    "getopts",
+    "gimli",
+    "hashbrown",
+    "hermit-abi",
+    "libc",
+    "memchr",
+    "miniz_oxide",
+    "object",
+    "r-efi",
+    "r-efi-alloc",
+    "rand",
+    "rand_core",
+    "rand_xorshift",
+    "rustc-demangle",
+    "unicode-width",
+    "unwinding",
+    "wasi",
+    "windows-sys",
+    "windows-targets",
+    "windows_aarch64_gnullvm",
+    "windows_aarch64_msvc",
+    "windows_i686_gnu",
+    "windows_i686_gnullvm",
+    "windows_i686_msvc",
+    "windows_x86_64_gnu",
+    "windows_x86_64_gnullvm",
+    "windows_x86_64_msvc",
+    // tidy-alphabetical-end
+];
+
 const PERMITTED_CRANELIFT_DEPENDENCIES: &[&str] = &[
     // tidy-alphabetical-start
     "ahash",
@@ -556,9 +595,8 @@ pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
             check_permitted_dependencies(&metadata, workspace, permitted_deps, crates, bad);
         }
 
-        if workspace == "." {
-            let runtime_ids = compute_runtime_crates(&metadata);
-            check_runtime_license_exceptions(&metadata, runtime_ids, bad);
+        if workspace == "library" {
+            check_runtime_license_exceptions(&metadata, bad);
             checked_runtime_licenses = true;
         }
     }
@@ -583,16 +621,8 @@ pub fn has_missing_submodule(root: &Path, submodules: &[&str]) -> bool {
 ///
 /// Unlike for tools we don't allow exceptions to the `LICENSES` list for the runtime with the sole
 /// exception of `fortanix-sgx-abi` which is only used on x86_64-fortanix-unknown-sgx.
-fn check_runtime_license_exceptions(
-    metadata: &Metadata,
-    runtime_ids: HashSet<&PackageId>,
-    bad: &mut bool,
-) {
+fn check_runtime_license_exceptions(metadata: &Metadata, bad: &mut bool) {
     for pkg in &metadata.packages {
-        if !runtime_ids.contains(&pkg.id) {
-            // Only checking dependencies of runtime libraries here.
-            continue;
-        }
         if pkg.source.is_none() {
             // No need to check local packages.
             continue;
@@ -613,20 +643,6 @@ fn check_runtime_license_exceptions(
                 continue;
             }
 
-            // This exception is due to the fact that the feature set of the
-            // `object` crate is different between rustc and libstd. In the
-            // standard library only a conservative set of features are enabled
-            // which notably does not include the `wasm` feature which pulls in
-            // this dependency. In the compiler, however, the `wasm` feature is
-            // enabled. This exception is intended to be here so long as the
-            // `EXCEPTIONS` above contains `wasmparser`, but once that goes away
-            // this can be removed.
-            if pkg.name == "wasmparser"
-                && pkg.license.as_deref() == Some("Apache-2.0 WITH LLVM-exception")
-            {
-                continue;
-            }
-
             tidy_error!(bad, "invalid license `{}` in `{}`", license, pkg.id);
         }
     }
@@ -758,16 +774,6 @@ fn pkg_from_id<'a>(metadata: &'a Metadata, id: &PackageId) -> &'a Package {
     metadata.packages.iter().find(|p| &p.id == id).unwrap()
 }
 
-/// Finds all the packages that are in the rust runtime.
-fn compute_runtime_crates<'a>(metadata: &'a Metadata) -> HashSet<&'a PackageId> {
-    let mut result = HashSet::new();
-    for name in RUNTIME_CRATES {
-        let id = &pkg_from_name(metadata, name).id;
-        deps_of(metadata, id, &mut result);
-    }
-    result
-}
-
 /// Recursively find all dependencies.
 fn deps_of<'a>(metadata: &'a Metadata, pkg_id: &'a PackageId, result: &mut HashSet<&'a PackageId>) {
     if !result.insert(pkg_id) {