diff --git a/.gitmodules b/.gitmodules
index 3fc6e45..70164d4 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -5,9 +5,6 @@
 [submodule "src/rust-installer"]
 	path = src/tools/rust-installer
 	url = https://github.com/rust-lang/rust-installer.git
-[submodule "src/liblibc"]
-	path = src/liblibc
-	url = https://github.com/rust-lang/libc.git
 [submodule "src/doc/nomicon"]
 	path = src/doc/nomicon
 	url = https://github.com/rust-lang-nursery/nomicon.git
@@ -23,9 +20,6 @@
 [submodule "src/tools/rls"]
 	path = src/tools/rls
 	url = https://github.com/rust-lang-nursery/rls.git
-[submodule "src/libcompiler_builtins"]
-	path = src/libcompiler_builtins
-	url = https://github.com/rust-lang-nursery/compiler-builtins.git
 [submodule "src/tools/clippy"]
 	path = src/tools/clippy
 	url = https://github.com/rust-lang-nursery/rust-clippy.git
@@ -35,9 +29,6 @@
 [submodule "src/tools/miri"]
 	path = src/tools/miri
 	url = https://github.com/solson/miri.git
-[submodule "src/dlmalloc"]
-	path = src/dlmalloc
-	url = https://github.com/alexcrichton/dlmalloc-rs.git
 [submodule "src/doc/rust-by-example"]
 	path = src/doc/rust-by-example
 	url = https://github.com/rust-lang/rust-by-example.git
@@ -67,6 +58,3 @@
 [submodule "src/doc/edition-guide"]
 	path = src/doc/edition-guide
 	url = https://github.com/rust-lang-nursery/edition-guide
-[submodule "src/rust-sgx"]
-	path = src/rust-sgx
-	url = https://github.com/fortanix/rust-sgx
diff --git a/Cargo.lock b/Cargo.lock
index c3c8812..d22a910 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -15,9 +15,9 @@
 name = "alloc"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
- "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -407,10 +407,11 @@
 
 [[package]]
 name = "compiler_builtins"
-version = "0.0.0"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "core 0.0.0",
+ "rustc-std-workspace-core 1.0.0",
 ]
 
 [[package]]
@@ -456,7 +457,7 @@
 name = "core"
 version = "0.0.0"
 dependencies = [
- "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -658,10 +659,12 @@
 
 [[package]]
 name = "dlmalloc"
-version = "0.0.0"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "compiler_builtins 0.0.0",
- "core 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-std-workspace-core 1.0.0",
 ]
 
 [[package]]
@@ -814,10 +817,11 @@
 
 [[package]]
 name = "fortanix-sgx-abi"
-version = "0.0.0"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "compiler_builtins 0.0.0",
- "core 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-std-workspace-core 1.0.0",
 ]
 
 [[package]]
@@ -1140,16 +1144,11 @@
 
 [[package]]
 name = "libc"
-version = "0.0.0"
-dependencies = [
- "compiler_builtins 0.0.0",
- "core 0.0.0",
-]
-
-[[package]]
-name = "libc"
 version = "0.2.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rustc-std-workspace-core 1.0.0",
+]
 
 [[package]]
 name = "libgit2-sys"
@@ -1520,9 +1519,9 @@
 name = "panic_abort"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
- "libc 0.0.0",
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1530,9 +1529,9 @@
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
- "libc 0.0.0",
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "unwind 0.0.0",
 ]
 
@@ -1683,7 +1682,7 @@
 version = "0.0.0"
 dependencies = [
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -1814,7 +1813,7 @@
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1836,7 +1835,7 @@
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1861,7 +1860,7 @@
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2243,6 +2242,13 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "rustc-std-workspace-core"
+version = "1.0.0"
+dependencies = [
+ "core 0.0.0",
+]
+
+[[package]]
 name = "rustc-workspace-hack"
 version = "1.0.0"
 dependencies = [
@@ -2284,7 +2290,7 @@
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2479,7 +2485,7 @@
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2531,7 +2537,7 @@
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2644,7 +2650,7 @@
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
 ]
 
@@ -2877,15 +2883,15 @@
  "alloc 0.0.0",
  "build_helper 0.1.0",
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
- "dlmalloc 0.0.0",
- "fortanix-sgx-abi 0.0.0",
- "libc 0.0.0",
+ "dlmalloc 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fortanix-sgx-abi 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
  "panic_abort 0.0.0",
  "panic_unwind 0.0.0",
  "profiler_builtins 0.0.0",
- "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_asan 0.0.0",
  "rustc_lsan 0.0.0",
  "rustc_msan 0.0.0",
@@ -3217,9 +3223,9 @@
 name = "unwind"
 version = "0.0.0"
 dependencies = [
- "compiler_builtins 0.0.0",
+ "compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "core 0.0.0",
- "libc 0.0.0",
+ "libc 0.2.45 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -3397,6 +3403,7 @@
 "checksum colored 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b0aa3473e85a3161b59845d6096b289bb577874cafeaf75ea1b1beaa6572c7fc"
 "checksum commoncrypto 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d056a8586ba25a1e4d61cb090900e495952c7886786fc55f909ab2f819b69007"
 "checksum commoncrypto-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1fed34f46747aa73dfaa578069fd8279d2818ade2b55f38f22a9401c7f4083e2"
+"checksum compiler_builtins 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "8ad611263b9f31bdb66e66227d3b781600fd1e68d5deee29b23f5e2ac9cb4892"
 "checksum compiletest_rs 0.3.17 (registry+https://github.com/rust-lang/crates.io-index)" = "89747fe073b7838343bd2c2445e7a7c2e0d415598f8925f0fa9205b9cdfc48cb"
 "checksum core-foundation 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4e2640d6d0bf22e82bed1b73c6aef8d5dd31e5abe6666c57e6d45e2649f4f887"
 "checksum core-foundation-sys 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "e7ca8a5221364ef15ce201e8ed2f609fc312682a8f4e0e3d4aa5879764e0fa3b"
@@ -3418,6 +3425,7 @@
 "checksum diff 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "3c2b69f912779fbb121ceb775d74d51e915af17aaebc38d28a592843a2dd0a3a"
 "checksum difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "524cbf6897b527295dff137cec09ecf3a05f4fddffd7dfcd1585403449e74198"
 "checksum directories 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "72d337a64190607d4fcca2cb78982c5dd57f4916e19696b48a575fa746b6cb0f"
+"checksum dlmalloc 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4c46c65de42b063004b31c67a98abe071089b289ff0919c660ed7ff4f59317f8"
 "checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
 "checksum elasticlunr-rs 2.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "a99a310cd1f9770e7bf8e48810c7bcbb0e078c8fb23a8c7bcf0da4c2bf61a455"
 "checksum ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f56c93cc076508c549d9bb747f79aa9b4eb098be7b8cad8830c3137ef52d1e00"
@@ -3434,6 +3442,7 @@
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f6f339eb8adc052cd2ca78910fda869aefa38d22d5cb648e6485e4d3fc06f3b1"
 "checksum foreign-types-shared 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "00b0228411908ca8685dba7fc2cdd70ec9990a6e753e89b6ac91a84c40fbaf4b"
+"checksum fortanix-sgx-abi 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "26105e20b4c3f7a319db1376b54ac9a46e5761e949405553375095d05a0cee4d"
 "checksum fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9564fc758e15025b46aa6643b1b77d047d1a56a1aea6e01002ac0c7026876213"
 "checksum fs_extra 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5f2a4a2034423744d2cc7ca2068453168dcdb82c438419e639a26bd87839c674"
 "checksum fst 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d94485a00b1827b861dd9d1a2cc9764f9044d4c535514c0760a5a2012ef3399f"
diff --git a/Cargo.toml b/Cargo.toml
index b763caa..667c557 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -65,6 +65,10 @@
 # here
 rustc-workspace-hack = { path = 'src/tools/rustc-workspace-hack' }
 
+# See comments in `tools/rustc-std-workspace-core/README.md` for what's going on
+# here
+rustc-std-workspace-core = { path = 'src/tools/rustc-std-workspace-core' }
+
 [patch."https://github.com/rust-lang/rust-clippy"]
 clippy_lints = { path = "src/tools/clippy/clippy_lints" }
 rustc_tools_util = { path = "src/tools/clippy/rustc_tools_util" }
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 2e792b6..c84abe42 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -152,11 +152,10 @@
 
     if builder.no_std(target) == Some(true) {
         // for no-std targets we only compile a few no_std crates
-        cargo.arg("--features").arg("c mem")
+        cargo
             .args(&["-p", "alloc"])
-            .args(&["-p", "compiler_builtins"])
             .arg("--manifest-path")
-            .arg(builder.src.join("src/rustc/compiler_builtins_shim/Cargo.toml"));
+            .arg(builder.src.join("src/liballoc/Cargo.toml"));
     } else {
         let features = builder.std_features();
 
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 1ae494b..f03eefb 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -857,12 +857,9 @@
         // (essentially libstd and all of its path dependencies)
         let std_src_dirs = [
             "src/build_helper",
-            "src/dlmalloc",
             "src/liballoc",
             "src/libbacktrace",
-            "src/libcompiler_builtins",
             "src/libcore",
-            "src/liblibc",
             "src/libpanic_abort",
             "src/libpanic_unwind",
             "src/librustc_asan",
@@ -871,21 +868,15 @@
             "src/librustc_tsan",
             "src/libstd",
             "src/libunwind",
-            "src/rustc/compiler_builtins_shim",
-            "src/rustc/libc_shim",
-            "src/rustc/dlmalloc_shim",
-            "src/rustc/fortanix-sgx-abi_shim",
             "src/libtest",
             "src/libterm",
             "src/libprofiler_builtins",
             "src/stdsimd",
             "src/libproc_macro",
-        ];
-        let std_src_dirs_exclude = [
-            "src/libcompiler_builtins/compiler-rt/test",
+            "src/tools/rustc-std-workspace-core",
         ];
 
-        copy_src_dirs(builder, &std_src_dirs[..], &std_src_dirs_exclude[..], &dst_src);
+        copy_src_dirs(builder, &std_src_dirs[..], &[], &dst_src);
         for file in src_files.iter() {
             builder.copy(&builder.src.join(file), &dst_src.join(file));
         }
@@ -909,7 +900,7 @@
     }
 }
 
-const CARGO_VENDOR_VERSION: &str = "0.1.19";
+const CARGO_VENDOR_VERSION: &str = "0.1.22";
 
 #[derive(Debug, PartialOrd, Ord, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct PlainSourceTarball;
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index c31db48..c879291 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -1134,10 +1134,10 @@
             let krate = &self.crates[&krate];
             if krate.is_local(self) {
                 ret.push(krate);
-                for dep in &krate.deps {
-                    if visited.insert(dep) && dep != "build_helper" {
-                        list.push(*dep);
-                    }
+            }
+            for dep in &krate.deps {
+                if visited.insert(dep) && dep != "build_helper" {
+                    list.push(*dep);
                 }
             }
         }
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index ca9894f..dc061fe 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1558,10 +1558,7 @@
         let builder = run.builder;
         run = run.krate("test");
         for krate in run.builder.in_tree_crates("std") {
-            if krate.is_local(&run.builder)
-                && !(krate.name.starts_with("rustc_") && krate.name.ends_with("san"))
-                && krate.name != "dlmalloc"
-            {
+            if !(krate.name.starts_with("rustc_") && krate.name.ends_with("san")) {
                 run = run.path(krate.local_path(&builder).to_str().unwrap());
             }
         }
diff --git a/src/build_helper/lib.rs b/src/build_helper/lib.rs
index 0cbb080..a580a87 100644
--- a/src/build_helper/lib.rs
+++ b/src/build_helper/lib.rs
@@ -224,14 +224,12 @@
 // Timestamps are created automatically when the result of `native_lib_boilerplate` goes out
 // of scope, so all the build actions should be completed until then.
 pub fn native_lib_boilerplate(
-    src_name: &str,
+    src_dir: &Path,
     out_name: &str,
     link_name: &str,
     search_subdir: &str,
 ) -> Result<NativeLibBoilerplate, ()> {
-    let current_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
-    let src_dir = current_dir.join("..").join(src_name);
-    rerun_if_changed_anything_in_dir(&src_dir);
+    rerun_if_changed_anything_in_dir(src_dir);
 
     let out_dir = env::var_os("RUSTBUILD_NATIVE_DIR").unwrap_or_else(||
         env::var_os("OUT_DIR").unwrap());
@@ -248,9 +246,9 @@
     );
 
     let timestamp = out_dir.join("rustbuild.timestamp");
-    if !up_to_date(Path::new("build.rs"), &timestamp) || !up_to_date(&src_dir, &timestamp) {
+    if !up_to_date(Path::new("build.rs"), &timestamp) || !up_to_date(src_dir, &timestamp) {
         Ok(NativeLibBoilerplate {
-            src_dir: src_dir,
+            src_dir: src_dir.to_path_buf(),
             out_dir: out_dir,
         })
     } else {
@@ -279,8 +277,11 @@
     } else {
         format!("static={}", link_name)
     };
+    // The source for `compiler-rt` comes from the `compiler-builtins` crate, so
+    // load our env var set by cargo to find the source code.
+    let dir = env::var_os("DEP_COMPILER_RT_COMPILER_RT").unwrap();
     let lib = native_lib_boilerplate(
-        "libcompiler_builtins/compiler-rt",
+        dir.as_ref(),
         sanitizer_name,
         &to_link,
         search_path,
diff --git a/src/dlmalloc b/src/dlmalloc
deleted file mode 160000
index de99f4b..0000000
--- a/src/dlmalloc
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit de99f4b0c886f5916cd1a146464276d65bef61b8
diff --git a/src/liballoc/Cargo.toml b/src/liballoc/Cargo.toml
index 642a43d..b7faee1 100644
--- a/src/liballoc/Cargo.toml
+++ b/src/liballoc/Cargo.toml
@@ -11,10 +11,10 @@
 
 [dependencies]
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = { version = "0.1.0", features = ['rustc-dep-of-std'] }
 
 [dev-dependencies]
-rand = "0.5"
+rand = "0.6"
 
 [[test]]
 name = "collectionstests"
diff --git a/src/liballoc/tests/binary_heap.rs b/src/liballoc/tests/binary_heap.rs
index b0d8fa6..536291d 100644
--- a/src/liballoc/tests/binary_heap.rs
+++ b/src/liballoc/tests/binary_heap.rs
@@ -14,7 +14,7 @@
 use std::panic::{self, AssertUnwindSafe};
 use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT, Ordering};
 
-use rand::{thread_rng, Rng};
+use rand::{thread_rng, seq::SliceRandom};
 
 #[test]
 fn test_iterator() {
@@ -332,7 +332,7 @@
             let panic_item = PanicOrd(i, true);
 
             // heapify the sane items
-            rng.shuffle(&mut panic_ords);
+            panic_ords.shuffle(&mut rng);
             let mut heap = BinaryHeap::from(panic_ords);
             let inner_data;
 
diff --git a/src/liballoc/tests/slice.rs b/src/liballoc/tests/slice.rs
index 787e495..6f31e6c 100644
--- a/src/liballoc/tests/slice.rs
+++ b/src/liballoc/tests/slice.rs
@@ -18,7 +18,7 @@
 use std::sync::atomic::{ATOMIC_USIZE_INIT, AtomicUsize};
 use std::thread;
 
-use rand::{Rng, RngCore, thread_rng};
+use rand::{Rng, RngCore, thread_rng, seq::SliceRandom};
 use rand::distributions::Standard;
 
 fn square(n: usize) -> usize {
@@ -459,7 +459,7 @@
     for i in 0..v.len() {
         v[i] = i as i32;
     }
-    v.sort_by(|_, _| *rng.choose(&[Less, Equal, Greater]).unwrap());
+    v.sort_by(|_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
     v.sort();
     for i in 0..v.len() {
         assert_eq!(v[i], i as i32);
diff --git a/src/libcompiler_builtins b/src/libcompiler_builtins
deleted file mode 160000
index 10f4f35..0000000
--- a/src/libcompiler_builtins
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 10f4f35f9670bb29715a8c1ec01284852d47ed35
diff --git a/src/libcore/Cargo.toml b/src/libcore/Cargo.toml
index 7fd61f0..fa2ab11 100644
--- a/src/libcore/Cargo.toml
+++ b/src/libcore/Cargo.toml
@@ -20,7 +20,7 @@
 path = "../libcore/benches/lib.rs"
 
 [dev-dependencies]
-rand = "0.5"
+rand = "0.6"
 
 [features]
 # Make panics and failed asserts immediately abort without formatting any message
diff --git a/src/libcore/tests/num/flt2dec/random.rs b/src/libcore/tests/num/flt2dec/random.rs
index 95dfcb5..21a7c9f 100644
--- a/src/libcore/tests/num/flt2dec/random.rs
+++ b/src/libcore/tests/num/flt2dec/random.rs
@@ -18,7 +18,8 @@
 use core::num::flt2dec::strategy::grisu::format_shortest_opt;
 use core::num::flt2dec::{decode, DecodableFloat, FullDecoded, Decoded};
 
-use rand::{FromEntropy, XorShiftRng};
+use rand::FromEntropy;
+use rand::rngs::SmallRng;
 use rand::distributions::{Distribution, Uniform};
 
 pub fn decode_finite<T: DecodableFloat>(v: T) -> Decoded {
@@ -71,7 +72,10 @@
 pub fn f32_random_equivalence_test<F, G>(f: F, g: G, k: usize, n: usize)
         where F: FnMut(&Decoded, &mut [u8]) -> Option<(usize, i16)>,
               G: FnMut(&Decoded, &mut [u8]) -> (usize, i16) {
-    let mut rng = XorShiftRng::from_entropy();
+    if cfg!(target_os = "emscripten") {
+        return // using rng pulls in i128 support, which doesn't work
+    }
+    let mut rng = SmallRng::from_entropy();
     let f32_range = Uniform::new(0x0000_0001u32, 0x7f80_0000);
     iterate("f32_random_equivalence_test", k, n, f, g, |_| {
         let x = f32::from_bits(f32_range.sample(&mut rng));
@@ -82,7 +86,10 @@
 pub fn f64_random_equivalence_test<F, G>(f: F, g: G, k: usize, n: usize)
         where F: FnMut(&Decoded, &mut [u8]) -> Option<(usize, i16)>,
               G: FnMut(&Decoded, &mut [u8]) -> (usize, i16) {
-    let mut rng = XorShiftRng::from_entropy();
+    if cfg!(target_os = "emscripten") {
+        return // using rng pulls in i128 support, which doesn't work
+    }
+    let mut rng = SmallRng::from_entropy();
     let f64_range = Uniform::new(0x0000_0000_0000_0001u64, 0x7ff0_0000_0000_0000);
     iterate("f64_random_equivalence_test", k, n, f, g, |_| {
         let x = f64::from_bits(f64_range.sample(&mut rng));
diff --git a/src/libcore/tests/slice.rs b/src/libcore/tests/slice.rs
index dba5a43..4f00ebe 100644
--- a/src/libcore/tests/slice.rs
+++ b/src/libcore/tests/slice.rs
@@ -1024,11 +1024,11 @@
 fn sort_unstable() {
     use core::cmp::Ordering::{Equal, Greater, Less};
     use core::slice::heapsort;
-    use rand::{FromEntropy, Rng, XorShiftRng};
+    use rand::{FromEntropy, Rng, rngs::SmallRng, seq::SliceRandom};
 
     let mut v = [0; 600];
     let mut tmp = [0; 600];
-    let mut rng = XorShiftRng::from_entropy();
+    let mut rng = SmallRng::from_entropy();
 
     for len in (2..25).chain(500..510) {
         let v = &mut v[0..len];
@@ -1073,7 +1073,7 @@
     for i in 0..v.len() {
         v[i] = i as i32;
     }
-    v.sort_unstable_by(|_, _| *rng.choose(&[Less, Equal, Greater]).unwrap());
+    v.sort_unstable_by(|_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
     v.sort_unstable();
     for i in 0..v.len() {
         assert_eq!(v[i], i as i32);
diff --git a/src/liblibc b/src/liblibc
deleted file mode 160000
index 5b40375..0000000
--- a/src/liblibc
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 5b403753da9ec8ff501adf34cb6d63b319b4a3ae
diff --git a/src/libpanic_abort/Cargo.toml b/src/libpanic_abort/Cargo.toml
index 633d273..e304e61 100644
--- a/src/libpanic_abort/Cargo.toml
+++ b/src/libpanic_abort/Cargo.toml
@@ -11,5 +11,5 @@
 
 [dependencies]
 core = { path = "../libcore" }
-libc = { path = "../rustc/libc_shim" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+libc = { version = "0.2", default-features = false }
+compiler_builtins = "0.1.0"
diff --git a/src/libpanic_unwind/Cargo.toml b/src/libpanic_unwind/Cargo.toml
index 74aaa4d..c9fce62 100644
--- a/src/libpanic_unwind/Cargo.toml
+++ b/src/libpanic_unwind/Cargo.toml
@@ -12,6 +12,6 @@
 [dependencies]
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
-libc = { path = "../rustc/libc_shim" }
+libc = { version = "0.2", default-features = false }
 unwind = { path = "../libunwind" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = "0.1.0"
diff --git a/src/libprofiler_builtins/Cargo.toml b/src/libprofiler_builtins/Cargo.toml
index 79192fb..7c95cf0 100644
--- a/src/libprofiler_builtins/Cargo.toml
+++ b/src/libprofiler_builtins/Cargo.toml
@@ -13,7 +13,7 @@
 
 [dependencies]
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = { version = "0.1.0", features = ['rustc-dep-of-std'] }
 
 [build-dependencies]
 cc = "1.0.1"
diff --git a/src/libprofiler_builtins/build.rs b/src/libprofiler_builtins/build.rs
index 8d6c7d6..db72ce7 100644
--- a/src/libprofiler_builtins/build.rs
+++ b/src/libprofiler_builtins/build.rs
@@ -56,9 +56,15 @@
         cfg.define("COMPILER_RT_HAS_UNAME", Some("1"));
     }
 
+    // The source for `compiler-rt` comes from the `compiler-builtins` crate, so
+    // load our env var set by cargo to find the source code.
+    let root = env::var_os("DEP_COMPILER_RT_COMPILER_RT").unwrap();
+    let root = Path::new(&root);
+
     for src in profile_sources {
-        cfg.file(Path::new("../libcompiler_builtins/compiler-rt/lib/profile").join(src));
+        cfg.file(root.join("lib").join("profile").join(src));
     }
 
+    cfg.warnings(false);
     cfg.compile("profiler-rt");
 }
diff --git a/src/librustc_asan/Cargo.toml b/src/librustc_asan/Cargo.toml
index 734564c..836caf2 100644
--- a/src/librustc_asan/Cargo.toml
+++ b/src/librustc_asan/Cargo.toml
@@ -16,4 +16,4 @@
 [dependencies]
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = "0.1.0"
diff --git a/src/librustc_lsan/Cargo.toml b/src/librustc_lsan/Cargo.toml
index 2573825..a8e11df 100644
--- a/src/librustc_lsan/Cargo.toml
+++ b/src/librustc_lsan/Cargo.toml
@@ -16,4 +16,4 @@
 [dependencies]
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = "0.1.0"
diff --git a/src/librustc_msan/Cargo.toml b/src/librustc_msan/Cargo.toml
index 2916567..78c39d0 100644
--- a/src/librustc_msan/Cargo.toml
+++ b/src/librustc_msan/Cargo.toml
@@ -16,4 +16,4 @@
 [dependencies]
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = "0.1.0"
diff --git a/src/librustc_resolve/diagnostics.rs b/src/librustc_resolve/diagnostics.rs
index 2681295..7730239 100644
--- a/src/librustc_resolve/diagnostics.rs
+++ b/src/librustc_resolve/diagnostics.rs
@@ -295,9 +295,8 @@
 Erroneous code example:
 
 ```compile_fail,E0259
-# #![feature(libc)]
 extern crate core;
-extern crate libc as core;
+extern crate std as core;
 
 fn main() {}
 ```
@@ -308,9 +307,8 @@
 Correct example:
 
 ```
-# #![feature(libc)]
 extern crate core;
-extern crate libc as other_name;
+extern crate std as other_name;
 
 fn main() {}
 ```
diff --git a/src/librustc_tsan/Cargo.toml b/src/librustc_tsan/Cargo.toml
index baadb64..f061827 100644
--- a/src/librustc_tsan/Cargo.toml
+++ b/src/librustc_tsan/Cargo.toml
@@ -16,4 +16,4 @@
 [dependencies]
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+compiler_builtins = "0.1.0"
diff --git a/src/libstd/Cargo.toml b/src/libstd/Cargo.toml
index 274d5be..41e778b 100644
--- a/src/libstd/Cargo.toml
+++ b/src/libstd/Cargo.toml
@@ -17,13 +17,13 @@
 panic_unwind = { path = "../libpanic_unwind", optional = true }
 panic_abort = { path = "../libpanic_abort" }
 core = { path = "../libcore" }
-libc = { path = "../rustc/libc_shim" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+libc = { version = "0.2.44", default-features = false, features = ['rustc-dep-of-std'] }
+compiler_builtins = { version = "0.1.1" }
 profiler_builtins = { path = "../libprofiler_builtins", optional = true }
 unwind = { path = "../libunwind" }
 
 [dev-dependencies]
-rand = "0.5"
+rand = "0.6.1"
 
 [target.x86_64-apple-darwin.dependencies]
 rustc_asan = { path = "../librustc_asan" }
@@ -36,10 +36,10 @@
 rustc_tsan = { path = "../librustc_tsan" }
 
 [target.'cfg(any(all(target_arch = "wasm32", not(target_os = "emscripten")), target_env = "sgx"))'.dependencies]
-dlmalloc = { path = '../rustc/dlmalloc_shim' }
+dlmalloc = { version = "0.1", features = ['rustc-dep-of-std'] }
 
 [target.x86_64-fortanix-unknown-sgx.dependencies]
-fortanix-sgx-abi = { path = "../rustc/fortanix-sgx-abi_shim" }
+fortanix-sgx-abi = { version = "0.3.1", features = ['rustc-dep-of-std'] }
 
 [build-dependencies]
 cc = "1.0"
diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 9d6e8c4..2386f13 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -82,7 +82,12 @@
 }
 
 fn build_libbacktrace(target: &str) -> Result<(), ()> {
-    let native = native_lib_boilerplate("libbacktrace", "libbacktrace", "backtrace", "")?;
+    let native = native_lib_boilerplate(
+        "../libbacktrace".as_ref(),
+        "libbacktrace",
+        "backtrace",
+        "",
+    )?;
 
     let mut build = cc::Build::new();
     build
diff --git a/src/libstd/fs.rs b/src/libstd/fs.rs
index b6a0ce6..d581ba1 100644
--- a/src/libstd/fs.rs
+++ b/src/libstd/fs.rs
@@ -2089,7 +2089,7 @@
     use fs::{self, File, OpenOptions};
     use io::{ErrorKind, SeekFrom};
     use path::Path;
-    use rand::{StdRng, FromEntropy, RngCore};
+    use rand::{rngs::StdRng, FromEntropy, RngCore};
     use str;
     use sys_common::io::test::{TempDir, tmpdir};
     use thread;
diff --git a/src/libstd/primitive_docs.rs b/src/libstd/primitive_docs.rs
index 3b2366a..7c1654f 100644
--- a/src/libstd/primitive_docs.rs
+++ b/src/libstd/primitive_docs.rs
@@ -426,7 +426,7 @@
 /// ## 3. Get it from C.
 ///
 /// ```
-/// # #![feature(libc)]
+/// # #![feature(rustc_private)]
 /// extern crate libc;
 ///
 /// use std::mem;
diff --git a/src/libstd/sys/unix/ext/fs.rs b/src/libstd/sys/unix/ext/fs.rs
index 7e65bbd..af2f199 100644
--- a/src/libstd/sys/unix/ext/fs.rs
+++ b/src/libstd/sys/unix/ext/fs.rs
@@ -348,7 +348,7 @@
     /// # Examples
     ///
     /// ```no_run
-    /// # #![feature(libc)]
+    /// # #![feature(rustc_private)]
     /// extern crate libc;
     /// use std::fs::OpenOptions;
     /// use std::os::unix::fs::OpenOptionsExt;
diff --git a/src/libunwind/Cargo.toml b/src/libunwind/Cargo.toml
index 4760461..2577d6d 100644
--- a/src/libunwind/Cargo.toml
+++ b/src/libunwind/Cargo.toml
@@ -13,5 +13,5 @@
 
 [dependencies]
 core = { path = "../libcore" }
-libc = { path = "../rustc/libc_shim" }
-compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
+libc = { version = "0.2.43", features = ['rustc-dep-of-std'], default-features = false }
+compiler_builtins = "0.1.0"
diff --git a/src/rust-sgx b/src/rust-sgx
deleted file mode 160000
index 9656260..0000000
--- a/src/rust-sgx
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 9656260888095f44830641ca7bb3da609a793451
diff --git a/src/rustc/compiler_builtins_shim/Cargo.toml b/src/rustc/compiler_builtins_shim/Cargo.toml
deleted file mode 100644
index 9804177..0000000
--- a/src/rustc/compiler_builtins_shim/Cargo.toml
+++ /dev/null
@@ -1,40 +0,0 @@
-[package]
-name = "compiler_builtins"
-authors = ["The Rust Project Developers"]
-version = "0.0.0"
-build = "../../libcompiler_builtins/build.rs"
-
-[lib]
-path = "../../libcompiler_builtins/src/lib.rs"
-test = false
-doctest = false
-
-[dependencies]
-# Specify the path to libcore; at the time of writing, removing this shim in
-# favor of using compiler-builtins from git results in a compilation failure:
-#
-# Building stage0 std artifacts (x86_64-apple-darwin -> x86_64-apple-darwin)
-#    Compiling compiler_builtins v0.1.0 (https://github.com/rust-lang-nursery/compiler-builtins.git#23f14d3f)
-# error[E0463]: can't find crate for `core`
-#
-# error: aborting due to previous error
-#
-# error: Could not compile `compiler_builtins`.
-#
-# Caused by:
-#   process didn't exit successfully: `/Users/tamird/src/rust/build/bootstrap/debug/rustc --crate-name compiler_builtins /Users/tamird/.cargo/git/checkouts/compiler-builtins-ec094dc45a0179c8/23f14d3/src/lib.rs --error-format json --crate-type lib --emit=dep-info,link -C opt-level=2 --cfg feature="c" --cfg feature="compiler-builtins" --cfg feature="default" --cfg feature="gcc" -C metadata=876d429e8d7eae1f -C extra-filename=-876d429e8d7eae1f --out-dir /Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/x86_64-apple-darwin/release/deps --target x86_64-apple-darwin -L dependency=/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/x86_64-apple-darwin/release/deps -L dependency=/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/release/deps --cap-lints allow -L native=/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/x86_64-apple-darwin/release/build/compiler_builtins-f18fab55928102ad/out -l static=compiler-rt` (exit code: 101)
-# thread 'main' panicked at 'command did not execute successfully: "/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0/bin/cargo" "build" "-j" "4" "--target" "x86_64-apple-darwin" "--release" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/Users/tamird/src/rust/src/libstd/Cargo.toml" "--message-format" "json"
-# expected success, got: exit code: 101', src/bootstrap/compile.rs:883:8
-#
-# See https://github.com/rust-lang/rfcs/pull/1133.
-core = { path = "../../libcore" }
-
-[build-dependencies]
-cc = "1.0.1"
-
-[features]
-c = []
-default = ["rustbuild", "compiler-builtins"]
-mem = []
-rustbuild = []
-compiler-builtins = []
diff --git a/src/rustc/compiler_builtins_shim/build.rs b/src/rustc/compiler_builtins_shim/build.rs
deleted file mode 100644
index b37543e..0000000
--- a/src/rustc/compiler_builtins_shim/build.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// This file is left intentionally empty (and not removed) to avoid an issue
-// where this crate is always considered dirty due to compiler-builtins'
-// `cargo:rerun-if-changed=build.rs` directive; since the path is relative, it
-// refers to this file when this shim crate is being built, and the absence of
-// this file is considered by cargo to be equivalent to it having changed.
diff --git a/src/rustc/dlmalloc_shim/Cargo.toml b/src/rustc/dlmalloc_shim/Cargo.toml
deleted file mode 100644
index b6f8550..0000000
--- a/src/rustc/dlmalloc_shim/Cargo.toml
+++ /dev/null
@@ -1,14 +0,0 @@
-[package]
-name = "dlmalloc"
-version = "0.0.0"
-authors = ["The Rust Project Developers"]
-
-[lib]
-path = "../../dlmalloc/src/lib.rs"
-test = false
-bench = false
-doc = false
-
-[dependencies]
-core = { path = "../../libcore" }
-compiler_builtins = { path = "../../rustc/compiler_builtins_shim" }
diff --git a/src/rustc/fortanix-sgx-abi_shim/Cargo.toml b/src/rustc/fortanix-sgx-abi_shim/Cargo.toml
deleted file mode 100644
index fd81d3d..0000000
--- a/src/rustc/fortanix-sgx-abi_shim/Cargo.toml
+++ /dev/null
@@ -1,14 +0,0 @@
-[package]
-name = "fortanix-sgx-abi"
-version = "0.0.0"
-authors = ["The Rust Project Developers"]
-
-[lib]
-path = "../../rust-sgx/fortanix-sgx-abi/src/lib.rs"
-test = false
-bench = false
-doc = false
-
-[dependencies]
-core = { path = "../../libcore" }
-compiler_builtins = { path = "../../rustc/compiler_builtins_shim" }
diff --git a/src/rustc/libc_shim/Cargo.toml b/src/rustc/libc_shim/Cargo.toml
deleted file mode 100644
index ee037ac..0000000
--- a/src/rustc/libc_shim/Cargo.toml
+++ /dev/null
@@ -1,40 +0,0 @@
-[package]
-name = "libc"
-version = "0.0.0"
-authors = ["The Rust Project Developers"]
-
-[lib]
-name = "libc"
-path = "../../liblibc/src/lib.rs"
-test = false
-bench = false
-doc = false
-
-[dependencies]
-# Specify the path to libcore; at the time of writing, removing this shim in
-# favor of using libc from git results in a compilation failure:
-#
-# Building stage0 std artifacts (x86_64-apple-darwin -> x86_64-apple-darwin)
-#    Compiling libc v0.0.0 (file:///Users/tamird/src/rust/src/rustc/libc_shim)
-# error[E0463]: can't find crate for `core`
-#
-# error: aborting due to previous error
-#
-# error: Could not compile `libc`.
-#
-# Caused by:
-#   process didn't exit successfully: `/Users/tamird/src/rust/build/bootstrap/debug/rustc --crate-name libc src/rustc/libc_shim/../../liblibc/src/lib.rs --error-format json --crate-type lib --emit=dep-info,link -C opt-level=2 --cfg feature="default" --cfg feature="no_std" --cfg feature="stdbuild" -C metadata=d758f87058112d7d -C extra-filename=-d758f87058112d7d --out-dir /Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/x86_64-apple-darwin/release/deps --target x86_64-apple-darwin -L dependency=/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/x86_64-apple-darwin/release/deps -L dependency=/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0-std/release/deps` (exit code: 101)
-# thread 'main' panicked at 'command did not execute successfully: "/Users/tamird/src/rust/build/x86_64-apple-darwin/stage0/bin/cargo" "build" "-j" "4" "--target" "x86_64-apple-darwin" "--release" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/Users/tamird/src/rust/src/libstd/Cargo.toml" "--message-format" "json"
-# expected success, got: exit code: 101', src/bootstrap/compile.rs:883:8
-#
-# See https://github.com/rust-lang/rfcs/pull/1133.
-core = { path = "../../libcore" }
-compiler_builtins = { path = "../compiler_builtins_shim" }
-
-
-[features]
-# Certain parts of libc are conditionally compiled differently than when used
-# outside rustc. See https://github.com/rust-lang/libc/search?l=Rust&q=stdbuild&type=&utf8=%E2%9C%93.
-stdbuild = []
-default = ["stdbuild", "align"]
-align = []
diff --git a/src/stage0.txt b/src/stage0.txt
index 9326e22..8369413 100644
--- a/src/stage0.txt
+++ b/src/stage0.txt
@@ -12,7 +12,7 @@
 # source tarball for a stable release you'll likely see `1.x.0` for rustc and
 # `0.x.0` for Cargo where they were released on `date`.
 
-date: 2018-10-30
+date: 2018-11-21
 rustc: beta
 cargo: beta
 
diff --git a/src/test/incremental/foreign.rs b/src/test/incremental/foreign.rs
index dbdebef..648e89b 100644
--- a/src/test/incremental/foreign.rs
+++ b/src/test/incremental/foreign.rs
@@ -13,7 +13,7 @@
 
 // revisions: rpass1
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/checkrust.rs b/src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/checkrust.rs
index 90ad601..0254c7c 100644
--- a/src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/checkrust.rs
+++ b/src/test/run-make-fulldeps/c-link-to-rust-va-list-fn/checkrust.rs
@@ -10,7 +10,7 @@
 
 #![crate_type = "staticlib"]
 #![feature(c_variadic)]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-make-fulldeps/issue-25581/test.rs b/src/test/run-make-fulldeps/issue-25581/test.rs
index 6717d16..b084092 100644
--- a/src/test/run-make-fulldeps/issue-25581/test.rs
+++ b/src/test/run-make-fulldeps/issue-25581/test.rs
@@ -8,14 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(libc)]
-
-extern crate libc;
-
 #[link(name = "test", kind = "static")]
 extern {
-    fn slice_len(s: &[u8]) -> libc::size_t;
-    fn slice_elem(s: &[u8], idx: libc::size_t) -> u8;
+    fn slice_len(s: &[u8]) -> usize;
+    fn slice_elem(s: &[u8], idx: usize) -> u8;
 }
 
 fn main() {
diff --git a/src/test/run-make-fulldeps/issue-26006/in/time/lib.rs b/src/test/run-make-fulldeps/issue-26006/in/time/lib.rs
index b1d07d5..1427250 100644
--- a/src/test/run-make-fulldeps/issue-26006/in/time/lib.rs
+++ b/src/test/run-make-fulldeps/issue-26006/in/time/lib.rs
@@ -7,7 +7,7 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
-#![feature(libc)]
+#![feature(rustc_private)]
 extern crate libc;
 
 fn main(){}
diff --git a/src/test/run-make-fulldeps/link-path-order/main.rs b/src/test/run-make-fulldeps/link-path-order/main.rs
index f3502e8..4d38dc8 100644
--- a/src/test/run-make-fulldeps/link-path-order/main.rs
+++ b/src/test/run-make-fulldeps/link-path-order/main.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass-valgrind/osx-frameworks.rs b/src/test/run-pass-valgrind/osx-frameworks.rs
index 468a20d..afa9374 100644
--- a/src/test/run-pass-valgrind/osx-frameworks.rs
+++ b/src/test/run-pass-valgrind/osx-frameworks.rs
@@ -11,7 +11,7 @@
 // no-prefer-dynamic
 // pretty-expanded FIXME #23616
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/anon-extern-mod.rs b/src/test/run-pass/anon-extern-mod.rs
index 16ca7bc..daa2bd6 100644
--- a/src/test/run-pass/anon-extern-mod.rs
+++ b/src/test/run-pass/anon-extern-mod.rs
@@ -11,7 +11,7 @@
 // pretty-expanded FIXME #23616
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/array-slice-vec/vec-macro-no-std.rs b/src/test/run-pass/array-slice-vec/vec-macro-no-std.rs
index 5091674..7a90a02 100644
--- a/src/test/run-pass/array-slice-vec/vec-macro-no-std.rs
+++ b/src/test/run-pass/array-slice-vec/vec-macro-no-std.rs
@@ -12,7 +12,7 @@
 
 // ignore-emscripten no no_std executables
 
-#![feature(lang_items, start, libc, alloc)]
+#![feature(lang_items, start, rustc_private, alloc)]
 #![no_std]
 
 extern crate std as other;
diff --git a/src/test/run-pass/auxiliary/anon-extern-mod-cross-crate-1.rs b/src/test/run-pass/auxiliary/anon-extern-mod-cross-crate-1.rs
index 741ce35..6b464c5 100644
--- a/src/test/run-pass/auxiliary/anon-extern-mod-cross-crate-1.rs
+++ b/src/test/run-pass/auxiliary/anon-extern-mod-cross-crate-1.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 #![crate_name="anonexternmod"]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/auxiliary/check_static_recursion_foreign_helper.rs b/src/test/run-pass/auxiliary/check_static_recursion_foreign_helper.rs
index cd36a8e..4d1acf3 100644
--- a/src/test/run-pass/auxiliary/check_static_recursion_foreign_helper.rs
+++ b/src/test/run-pass/auxiliary/check_static_recursion_foreign_helper.rs
@@ -10,7 +10,7 @@
 
 // Helper definition for test/run-pass/check-static-recursion-foreign.rs.
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 #![crate_name = "check_static_recursion_foreign_helper"]
 #![crate_type = "lib"]
diff --git a/src/test/run-pass/auxiliary/foreign_lib.rs b/src/test/run-pass/auxiliary/foreign_lib.rs
index cef3627..465feb8 100644
--- a/src/test/run-pass/auxiliary/foreign_lib.rs
+++ b/src/test/run-pass/auxiliary/foreign_lib.rs
@@ -10,7 +10,7 @@
 
 #![crate_name="foreign_lib"]
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 pub mod rustrt {
     extern crate libc;
diff --git a/src/test/run-pass/c-stack-as-value.rs b/src/test/run-pass/c-stack-as-value.rs
index df4989d..1f29a52 100644
--- a/src/test/run-pass/c-stack-as-value.rs
+++ b/src/test/run-pass/c-stack-as-value.rs
@@ -11,7 +11,7 @@
 // pretty-expanded FIXME #23616
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 mod rustrt {
     extern crate libc;
diff --git a/src/test/run-pass/c-stack-returning-int64.rs b/src/test/run-pass/c-stack-returning-int64.rs
index 56a0437..7dd3b9a 100644
--- a/src/test/run-pass/c-stack-returning-int64.rs
+++ b/src/test/run-pass/c-stack-returning-int64.rs
@@ -10,7 +10,7 @@
 
 // ignore-wasm32-bare no libc to test with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/check-static-recursion-foreign.rs b/src/test/run-pass/check-static-recursion-foreign.rs
index a95870c..15f509a 100644
--- a/src/test/run-pass/check-static-recursion-foreign.rs
+++ b/src/test/run-pass/check-static-recursion-foreign.rs
@@ -16,7 +16,7 @@
 
 // pretty-expanded FIXME #23616
 
-#![feature(custom_attribute, libc)]
+#![feature(custom_attribute, rustc_private)]
 
 extern crate check_static_recursion_foreign_helper;
 extern crate libc;
diff --git a/src/test/run-pass/command-before-exec.rs b/src/test/run-pass/command-before-exec.rs
index 5d8bc31..b78fa84 100644
--- a/src/test/run-pass/command-before-exec.rs
+++ b/src/test/run-pass/command-before-exec.rs
@@ -13,7 +13,7 @@
 // ignore-cloudabi no processes
 // ignore-emscripten no processes
 
-#![feature(process_exec, libc)]
+#![feature(process_exec, rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/consts/auxiliary/anon-extern-mod-cross-crate-1.rs b/src/test/run-pass/consts/auxiliary/anon-extern-mod-cross-crate-1.rs
index 741ce35..6b464c5 100644
--- a/src/test/run-pass/consts/auxiliary/anon-extern-mod-cross-crate-1.rs
+++ b/src/test/run-pass/consts/auxiliary/anon-extern-mod-cross-crate-1.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 #![crate_name="anonexternmod"]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/core-run-destroy.rs b/src/test/run-pass/core-run-destroy.rs
index 51e26ff..9023326 100644
--- a/src/test/run-pass/core-run-destroy.rs
+++ b/src/test/run-pass/core-run-destroy.rs
@@ -20,7 +20,7 @@
 // memory, which makes for some *confusing* logs. That's why these are here
 // instead of in std.
 
-#![feature(libc, duration)]
+#![feature(rustc_private, duration)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/cross-crate/auxiliary/anon-extern-mod-cross-crate-1.rs b/src/test/run-pass/cross-crate/auxiliary/anon-extern-mod-cross-crate-1.rs
index 741ce35..6b464c5 100644
--- a/src/test/run-pass/cross-crate/auxiliary/anon-extern-mod-cross-crate-1.rs
+++ b/src/test/run-pass/cross-crate/auxiliary/anon-extern-mod-cross-crate-1.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 #![crate_name="anonexternmod"]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/env-funky-keys.rs b/src/test/run-pass/env-funky-keys.rs
index 12e1cbe..7e7899c 100644
--- a/src/test/run-pass/env-funky-keys.rs
+++ b/src/test/run-pass/env-funky-keys.rs
@@ -16,7 +16,7 @@
 // ignore-emscripten no execve
 // no-prefer-dynamic
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/env-null-vars.rs b/src/test/run-pass/env-null-vars.rs
index 9a46199..cdbecf1 100644
--- a/src/test/run-pass/env-null-vars.rs
+++ b/src/test/run-pass/env-null-vars.rs
@@ -15,7 +15,7 @@
 
 // issue-53200
 
-#![feature(libc)]
+#![feature(rustc_private)]
 extern crate libc;
 
 use std::env;
diff --git a/src/test/run-pass/extern/auxiliary/extern-crosscrate-source.rs b/src/test/run-pass/extern/auxiliary/extern-crosscrate-source.rs
index 150dffe..d20d9db 100644
--- a/src/test/run-pass/extern/auxiliary/extern-crosscrate-source.rs
+++ b/src/test/run-pass/extern/auxiliary/extern-crosscrate-source.rs
@@ -10,7 +10,7 @@
 
 #![crate_name="externcallback"]
 #![crate_type = "lib"]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/extern/extern-call-deep.rs b/src/test/run-pass/extern/extern-call-deep.rs
index 6e8d94b..f6eff60 100644
--- a/src/test/run-pass/extern/extern-call-deep.rs
+++ b/src/test/run-pass/extern/extern-call-deep.rs
@@ -11,7 +11,7 @@
 // run-pass
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/extern/extern-call-deep2.rs b/src/test/run-pass/extern/extern-call-deep2.rs
index 28157c5..8cb0477 100644
--- a/src/test/run-pass/extern/extern-call-deep2.rs
+++ b/src/test/run-pass/extern/extern-call-deep2.rs
@@ -12,7 +12,7 @@
 #![allow(unused_must_use)]
 // ignore-emscripten no threads support
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 use std::thread;
diff --git a/src/test/run-pass/extern/extern-call-indirect.rs b/src/test/run-pass/extern/extern-call-indirect.rs
index 1badb10..d20721f 100644
--- a/src/test/run-pass/extern/extern-call-indirect.rs
+++ b/src/test/run-pass/extern/extern-call-indirect.rs
@@ -11,7 +11,7 @@
 // run-pass
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/extern/extern-call-scrub.rs b/src/test/run-pass/extern/extern-call-scrub.rs
index ea18069..5e158c2 100644
--- a/src/test/run-pass/extern/extern-call-scrub.rs
+++ b/src/test/run-pass/extern/extern-call-scrub.rs
@@ -16,7 +16,7 @@
 
 // ignore-emscripten no threads support
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 use std::thread;
diff --git a/src/test/run-pass/extern/extern-crosscrate.rs b/src/test/run-pass/extern/extern-crosscrate.rs
index c6fccbe..b99e27a 100644
--- a/src/test/run-pass/extern/extern-crosscrate.rs
+++ b/src/test/run-pass/extern/extern-crosscrate.rs
@@ -12,7 +12,7 @@
 // aux-build:extern-crosscrate-source.rs
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate externcallback;
 extern crate libc;
diff --git a/src/test/run-pass/fds-are-cloexec.rs b/src/test/run-pass/fds-are-cloexec.rs
index a5ae0ae..33e64d8 100644
--- a/src/test/run-pass/fds-are-cloexec.rs
+++ b/src/test/run-pass/fds-are-cloexec.rs
@@ -14,7 +14,7 @@
 // ignore-emscripten no processes
 // ignore-haiku
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/foreign/auxiliary/foreign_lib.rs b/src/test/run-pass/foreign/auxiliary/foreign_lib.rs
index cef3627..465feb8 100644
--- a/src/test/run-pass/foreign/auxiliary/foreign_lib.rs
+++ b/src/test/run-pass/foreign/auxiliary/foreign_lib.rs
@@ -10,7 +10,7 @@
 
 #![crate_name="foreign_lib"]
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 pub mod rustrt {
     extern crate libc;
diff --git a/src/test/run-pass/foreign/foreign-call-no-runtime.rs b/src/test/run-pass/foreign/foreign-call-no-runtime.rs
index 4837f78..e35ec88 100644
--- a/src/test/run-pass/foreign/foreign-call-no-runtime.rs
+++ b/src/test/run-pass/foreign/foreign-call-no-runtime.rs
@@ -11,7 +11,7 @@
 // run-pass
 // ignore-emscripten no threads support
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/foreign/foreign-fn-linkname.rs b/src/test/run-pass/foreign/foreign-fn-linkname.rs
index 7587660..8fe90b7 100644
--- a/src/test/run-pass/foreign/foreign-fn-linkname.rs
+++ b/src/test/run-pass/foreign/foreign-fn-linkname.rs
@@ -11,7 +11,7 @@
 // run-pass
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 use std::ffi::CString;
diff --git a/src/test/run-pass/foreign/foreign-no-abi.rs b/src/test/run-pass/foreign/foreign-no-abi.rs
index 1d35f08..49ddd09 100644
--- a/src/test/run-pass/foreign/foreign-no-abi.rs
+++ b/src/test/run-pass/foreign/foreign-no-abi.rs
@@ -14,7 +14,7 @@
 // ignore-wasm32-bare no libc to test ffi with
 // pretty-expanded FIXME #23616
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 mod rustrt {
     extern crate libc;
diff --git a/src/test/run-pass/foreign/foreign2.rs b/src/test/run-pass/foreign/foreign2.rs
index bd6c8e6..f8942bc 100644
--- a/src/test/run-pass/foreign/foreign2.rs
+++ b/src/test/run-pass/foreign/foreign2.rs
@@ -13,7 +13,7 @@
 // ignore-wasm32-bare no libc to test ffi with
 // pretty-expanded FIXME #23616
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/invalid_const_promotion.rs b/src/test/run-pass/invalid_const_promotion.rs
index 0f354e1..3b8a265 100644
--- a/src/test/run-pass/invalid_const_promotion.rs
+++ b/src/test/run-pass/invalid_const_promotion.rs
@@ -15,7 +15,7 @@
 // compile-flags: -C debug_assertions=yes
 
 #![stable(feature = "rustc", since = "1.0.0")]
-#![feature(const_fn, libc, staged_api, rustc_attrs)]
+#![feature(const_fn, rustc_private, staged_api, rustc_attrs)]
 #![allow(const_err)]
 
 extern crate libc;
diff --git a/src/test/run-pass/issues/issue-13259-windows-tcb-trash.rs b/src/test/run-pass/issues/issue-13259-windows-tcb-trash.rs
index de18e09..9c983ea 100644
--- a/src/test/run-pass/issues/issue-13259-windows-tcb-trash.rs
+++ b/src/test/run-pass/issues/issue-13259-windows-tcb-trash.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // run-pass
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/issues/issue-2214.rs b/src/test/run-pass/issues/issue-2214.rs
index 8329847..f3795c2 100644
--- a/src/test/run-pass/issues/issue-2214.rs
+++ b/src/test/run-pass/issues/issue-2214.rs
@@ -11,7 +11,7 @@
 // run-pass
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/issues/issue-30490.rs b/src/test/run-pass/issues/issue-30490.rs
index 500999c..47f60fb 100644
--- a/src/test/run-pass/issues/issue-30490.rs
+++ b/src/test/run-pass/issues/issue-30490.rs
@@ -18,7 +18,7 @@
 // where the descriptors to inherit were already stdio descriptors.
 // This test checks to avoid that regression.
 
-#![cfg_attr(unix, feature(libc))]
+#![cfg_attr(unix, feature(rustc_private))]
 #![cfg_attr(windows, allow(unused_imports))]
 
 #[cfg(unix)]
diff --git a/src/test/run-pass/issues/issue-3656.rs b/src/test/run-pass/issues/issue-3656.rs
index 63b2740..99a7244 100644
--- a/src/test/run-pass/issues/issue-3656.rs
+++ b/src/test/run-pass/issues/issue-3656.rs
@@ -19,7 +19,7 @@
 // pretty-expanded FIXME #23616
 // ignore-wasm32-bare no libc to test with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 use libc::{c_uint, uint32_t, c_void};
diff --git a/src/test/run-pass/no-stdio.rs b/src/test/run-pass/no-stdio.rs
index d342417..2f5bfbb 100644
--- a/src/test/run-pass/no-stdio.rs
+++ b/src/test/run-pass/no-stdio.rs
@@ -12,7 +12,7 @@
 // ignore-cloudabi no processes
 // ignore-emscripten no processes
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/out-of-stack.rs b/src/test/run-pass/out-of-stack.rs
index cd0f7cd..1c714e7 100644
--- a/src/test/run-pass/out-of-stack.rs
+++ b/src/test/run-pass/out-of-stack.rs
@@ -16,7 +16,7 @@
 // ignore-emscripten no processes
 
 #![feature(asm)]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 #[cfg(unix)]
 extern crate libc;
diff --git a/src/test/run-pass/rfcs/rfc-1014-2.rs b/src/test/run-pass/rfcs/rfc-1014-2.rs
index 7fbc0d1..257c7f5 100644
--- a/src/test/run-pass/rfcs/rfc-1014-2.rs
+++ b/src/test/run-pass/rfcs/rfc-1014-2.rs
@@ -11,7 +11,7 @@
 // run-pass
 #![allow(dead_code)]
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/rfcs/rfc-1014.rs b/src/test/run-pass/rfcs/rfc-1014.rs
index d101c3c..578a7f4 100644
--- a/src/test/run-pass/rfcs/rfc-1014.rs
+++ b/src/test/run-pass/rfcs/rfc-1014.rs
@@ -13,7 +13,7 @@
 // ignore-cloudabi stdout does not map to file descriptor 1 by default
 // ignore-wasm32-bare no libc
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/segfault-no-out-of-stack.rs b/src/test/run-pass/segfault-no-out-of-stack.rs
index a85fe67..961b802 100644
--- a/src/test/run-pass/segfault-no-out-of-stack.rs
+++ b/src/test/run-pass/segfault-no-out-of-stack.rs
@@ -12,7 +12,7 @@
 // ignore-cloudabi can't run commands
 // ignore-emscripten can't run commands
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/signal-alternate-stack-cleanup.rs b/src/test/run-pass/signal-alternate-stack-cleanup.rs
index ad099f8..a79ab20 100644
--- a/src/test/run-pass/signal-alternate-stack-cleanup.rs
+++ b/src/test/run-pass/signal-alternate-stack-cleanup.rs
@@ -16,7 +16,7 @@
 // ignore-wasm32-bare no libc
 // ignore-windows
 
-#![feature(libc)]
+#![feature(rustc_private)]
 extern crate libc;
 
 use libc::*;
diff --git a/src/test/run-pass/statics/static-mut-foreign.rs b/src/test/run-pass/statics/static-mut-foreign.rs
index d9e43dd..460d66a 100644
--- a/src/test/run-pass/statics/static-mut-foreign.rs
+++ b/src/test/run-pass/statics/static-mut-foreign.rs
@@ -15,7 +15,7 @@
 
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/run-pass/wait-forked-but-failed-child.rs b/src/test/run-pass/wait-forked-but-failed-child.rs
index dc47108..d822b67 100644
--- a/src/test/run-pass/wait-forked-but-failed-child.rs
+++ b/src/test/run-pass/wait-forked-but-failed-child.rs
@@ -11,7 +11,7 @@
 // ignore-cloudabi no processes
 // ignore-emscripten no processes
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/ui/error-codes/E0259.rs b/src/test/ui/error-codes/E0259.rs
index 5a47541..b3e633a 100644
--- a/src/test/ui/error-codes/E0259.rs
+++ b/src/test/ui/error-codes/E0259.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(alloc, libc)]
+#![feature(alloc, rustc_private)]
 #![allow(unused_extern_crates)]
 
 extern crate alloc;
diff --git a/src/test/ui/extern/extern-const.fixed b/src/test/ui/extern/extern-const.fixed
index dca5698..fb17934 100644
--- a/src/test/ui/extern/extern-const.fixed
+++ b/src/test/ui/extern/extern-const.fixed
@@ -7,7 +7,7 @@
 // run-rustfix
 // ignore-wasm32 no external library to link to.
 // compile-flags: -g -Z continue-parse-after-error
-#![feature(libc)]
+#![feature(rustc_private)]
 extern crate libc;
 
 #[link(name = "rust_test_helpers", kind = "static")]
diff --git a/src/test/ui/extern/extern-const.rs b/src/test/ui/extern/extern-const.rs
index 07dbe54..f2585f5 100644
--- a/src/test/ui/extern/extern-const.rs
+++ b/src/test/ui/extern/extern-const.rs
@@ -7,7 +7,7 @@
 // run-rustfix
 // ignore-wasm32 no external library to link to.
 // compile-flags: -g -Z continue-parse-after-error
-#![feature(libc)]
+#![feature(rustc_private)]
 extern crate libc;
 
 #[link(name = "rust_test_helpers", kind = "static")]
diff --git a/src/test/ui/issues/issue-1251.rs b/src/test/ui/issues/issue-1251.rs
index b42404c..125f6e1 100644
--- a/src/test/ui/issues/issue-1251.rs
+++ b/src/test/ui/issues/issue-1251.rs
@@ -14,7 +14,7 @@
 // pretty-expanded FIXME #23616
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 #![crate_id="rust_get_test_int"]
 
diff --git a/src/test/ui/issues/issue-22034.rs b/src/test/ui/issues/issue-22034.rs
index 2708de2..bee324f 100644
--- a/src/test/ui/issues/issue-22034.rs
+++ b/src/test/ui/issues/issue-22034.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/ui/issues/issue-37887.stderr b/src/test/ui/issues/issue-37887.stderr
index 48fb6c2..7a5a5cd 100644
--- a/src/test/ui/issues/issue-37887.stderr
+++ b/src/test/ui/issues/issue-37887.stderr
@@ -4,13 +4,13 @@
 LL |     use libc::*; //~ ERROR unresolved import
    |         ^^^^ maybe a missing `extern crate libc;`?
 
-error[E0658]: use of unstable library feature 'libc': use `libc` from crates.io (see issue #27783)
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead? (see issue #27812)
   --> $DIR/issue-37887.rs:12:5
    |
 LL |     extern crate libc; //~ ERROR use of unstable
    |     ^^^^^^^^^^^^^^^^^^
    |
-   = help: add #![feature(libc)] to the crate attributes to enable
+   = help: add #![feature(rustc_private)] to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/lint/lint-ctypes.rs b/src/test/ui/lint/lint-ctypes.rs
index e09aaba..4c9f1f9 100644
--- a/src/test/ui/lint/lint-ctypes.rs
+++ b/src/test/ui/lint/lint-ctypes.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 #![deny(improper_ctypes)]
-#![feature(libc)]
+#![feature(rustc_private)]
 
 #![allow(private_in_public)]
 
diff --git a/src/test/ui/non-copyable-void.rs b/src/test/ui/non-copyable-void.rs
index 63e5f96..3599190 100644
--- a/src/test/ui/non-copyable-void.rs
+++ b/src/test/ui/non-copyable-void.rs
@@ -10,7 +10,7 @@
 
 // ignore-wasm32-bare no libc to test ffi with
 
-#![feature(libc)]
+#![feature(rustc_private)]
 
 extern crate libc;
 
diff --git a/src/test/ui/unnecessary-extern-crate.rs b/src/test/ui/unnecessary-extern-crate.rs
index 110cfef..4eb3c3d 100644
--- a/src/test/ui/unnecessary-extern-crate.rs
+++ b/src/test/ui/unnecessary-extern-crate.rs
@@ -11,7 +11,7 @@
 // edition:2018
 
 #![deny(unused_extern_crates)]
-#![feature(alloc, test, libc, crate_visibility_modifier)]
+#![feature(alloc, test, rustc_private, crate_visibility_modifier)]
 
 extern crate libc;
 //~^ ERROR unused extern crate
diff --git a/src/tools/rustc-std-workspace-core/Cargo.toml b/src/tools/rustc-std-workspace-core/Cargo.toml
new file mode 100644
index 0000000..f000d63
--- /dev/null
+++ b/src/tools/rustc-std-workspace-core/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "rustc-std-workspace-core"
+version = "1.0.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+license = 'MIT/Apache-2.0'
+description = """
+Hack for the compiler's own build system
+"""
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+core = { path = "../../libcore" }
diff --git a/src/tools/rustc-std-workspace-core/README.md b/src/tools/rustc-std-workspace-core/README.md
new file mode 100644
index 0000000..9c2b1fa
--- /dev/null
+++ b/src/tools/rustc-std-workspace-core/README.md
@@ -0,0 +1,29 @@
+# The `rustc-std-workspace-core` crate
+
+This crate is a shim and empty crate which simply depends on `libcore` and
+reexports all of its contents. The crate is the crux of empowering the standard
+library to depend on crates from crates.io
+
+Crates on crates.io that the standard library depend on the
+`rustc-std-workspace-core` crate from crates.io. On crates.io, however, this
+crate is empty. We use `[patch]` to override it to this crate in this
+repository. As a result, crates on crates.io will draw a dependency edge to
+`libcore`, the version defined in this repository. That should draw all the
+dependency edges to ensure Cargo builds crates successfully!
+
+Note that crates on crates.io need to depend on this crate with the name `core`
+for everything to work correctly. To do that they can use:
+
+```toml
+core = { version = "1.0.0", optional = true, package = 'rustc-std-workspace-core' }
+```
+
+Through the use of the `package` key the crate is renamed to `core`, meaning
+it'll look like
+
+```
+--extern core=.../librustc_std_workspace_core-XXXXXXX.rlib
+```
+
+when Cargo invokes the compiler, satisfying the implicit `extern crate core`
+directive injected by the compiler.
diff --git a/src/tools/rustc-std-workspace-core/lib.rs b/src/tools/rustc-std-workspace-core/lib.rs
new file mode 100644
index 0000000..e2946fe
--- /dev/null
+++ b/src/tools/rustc-std-workspace-core/lib.rs
@@ -0,0 +1,6 @@
+#![feature(no_core)]
+#![no_core]
+
+extern crate core;
+
+pub use core::*;
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index e275892..2b5cff6 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -53,6 +53,7 @@
     "bytesize",           // Apache-2.0, cargo
     "im-rc",              // MPL-2.0+, cargo
     "adler32",            // BSD-3-Clause AND Zlib, cargo dep that isn't used
+    "fortanix-sgx-abi",   // MPL-2.0+, libstd but only for sgx target
 ];
 
 /// Which crates to check against the whitelist?
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 53db589..614d205 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -56,15 +56,11 @@
 
 fn filter_dirs(path: &Path) -> bool {
     let skip = [
-        "src/dlmalloc",
         "src/llvm",
         "src/llvm-emscripten",
         "src/libbacktrace",
-        "src/libcompiler_builtins",
         "src/librustc_data_structures/owning_ref",
-        "src/compiler-rt",
-        "src/liblibc",
-        "src/rt/hoedown",
+        "src/vendor",
         "src/tools/cargo",
         "src/tools/clang",
         "src/tools/rls",
diff --git a/src/tools/tidy/src/pal.rs b/src/tools/tidy/src/pal.rs
index 822db25..acf7202 100644
--- a/src/tools/tidy/src/pal.rs
+++ b/src/tools/tidy/src/pal.rs
@@ -26,7 +26,6 @@
 //! exceptions:
 //!
 //! - core may not have platform-specific code
-//! - libcompiler_builtins may have platform-specific code
 //! - libpanic_abort may have platform-specific code
 //! - libpanic_unwind may have platform-specific code
 //! - libunwind may have platform-specific code
@@ -50,8 +49,6 @@
 // Paths that may contain platform-specific code
 const EXCEPTION_PATHS: &[&str] = &[
     // std crates
-    "src/libcompiler_builtins",
-    "src/liblibc",
     "src/libpanic_abort",
     "src/libpanic_unwind",
     "src/libunwind",