diff --git a/.gitmodules b/.gitmodules
index 39288a7ae4907..36017db22b27e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -2,9 +2,6 @@
 	path = src/llvm
 	url = https://github.com/rust-lang/llvm.git
 	branch = master
-[submodule "src/compiler-rt"]
-	path = src/compiler-rt
-	url = https://github.com/rust-lang/compiler-rt.git
 [submodule "src/rt/hoedown"]
 	path = src/rt/hoedown
 	url = https://github.com/rust-lang/hoedown.git
@@ -17,3 +14,7 @@
 [submodule "src/liblibc"]
 	path = src/liblibc
 	url = https://github.com/rust-lang/libc.git
+[submodule "src/libcompiler_builtins"]
+	path = src/libcompiler_builtins
+	url = git://github.com/japaric/rustc-builtins.git
+	branch = upstream
diff --git a/mk/crates.mk b/mk/crates.mk
index efe7a57980186..bde4244fb81c3 100644
--- a/mk/crates.mk
+++ b/mk/crates.mk
@@ -228,3 +228,4 @@ $(foreach crate,$(TOOLS),$(eval $(call RUST_TOOL,$(crate))))
 
 CRATEFILE_libc := $(SREL)src/liblibc/src/lib.rs
 RUSTFLAGS_libc := --cfg stdbuild
+CRATEFILE_compiler_builtins := $(SREL)src/libcompiler_builtins/src/lib.rs
diff --git a/mk/rt.mk b/mk/rt.mk
index a67bded288e20..e20a8d7664410 100644
--- a/mk/rt.mk
+++ b/mk/rt.mk
@@ -319,7 +319,6 @@ COMPRT_OBJS_$(1) += \
   arm/clzsi2.o \
   arm/comparesf2.o \
   arm/divmodsi4.o \
-  arm/divsi3.o \
   arm/modsi3.o \
   arm/switch16.o \
   arm/switch32.o \
@@ -400,13 +399,9 @@ endif
 
 $(foreach intrinsic,absvdi2.o \
   absvsi2.o \
-  adddf3.o \
-  addsf3.o \
   addvdi3.o \
   addvsi3.o \
   apple_versioning.o \
-  ashldi3.o \
-  ashrdi3.o \
   clear_cache.o \
   clzdi2.o \
   clzsi2.o \
@@ -417,12 +412,8 @@ $(foreach intrinsic,absvdi2.o \
   ctzsi2.o \
   divdc3.o \
   divdf3.o \
-  divdi3.o \
-  divmoddi4.o \
-  divmodsi4.o \
   divsc3.o \
   divsf3.o \
-  divsi3.o \
   divxc3.o \
   extendsfdf2.o \
   extendhfsf2.o \
@@ -449,14 +440,8 @@ $(foreach intrinsic,absvdi2.o \
   floatunsidf.o \
   floatunsisf.o \
   int_util.o \
-  lshrdi3.o \
-  moddi3.o \
-  modsi3.o \
   muldc3.o \
   muldf3.o \
-  muldi3.o \
-  mulodi4.o \
-  mulosi4.o \
   muloti4.o \
   mulsc3.o \
   mulsf3.o \
@@ -472,8 +457,6 @@ $(foreach intrinsic,absvdi2.o \
   paritysi2.o \
   popcountdi2.o \
   popcountsi2.o \
-  powidf2.o \
-  powisf2.o \
   powixf2.o \
   subdf3.o \
   subsf3.o \
@@ -482,13 +465,7 @@ $(foreach intrinsic,absvdi2.o \
   truncdfhf2.o \
   truncdfsf2.o \
   truncsfhf2.o \
-  ucmpdi2.o \
-  udivdi3.o \
-  udivmoddi4.o \
-  udivmodsi4.o \
-  udivsi3.o \
-  umoddi3.o \
-  umodsi3.o,
+  ucmpdi2.o,
   $(call ADD_INTRINSIC,$(1),$(intrinsic)))
 
 ifeq ($$(findstring ios,$(1)),)
@@ -585,12 +562,12 @@ endif
 
 COMPRT_OBJS_$(1) := $$(COMPRT_OBJS_$(1):%=$$(COMPRT_BUILD_DIR_$(1))/%)
 
-$$(COMPRT_BUILD_DIR_$(1))/%.o: $(S)src/compiler-rt/lib/builtins/%.c
+$$(COMPRT_BUILD_DIR_$(1))/%.o: $(S)src/libcompiler_builtins/compiler-rt/compiler-rt-cdylib/compiler-rt/lib/builtins/%.c
 	@mkdir -p $$(@D)
 	@$$(call E, compile: $$@)
 	$$(Q)$$(call CFG_COMPILE_C_$(1),$$@,$$<)
 
-$$(COMPRT_BUILD_DIR_$(1))/%.o: $(S)src/compiler-rt/lib/builtins/%.S \
+$$(COMPRT_BUILD_DIR_$(1))/%.o: $(S)src/libcompiler_builtins/compiler-rt/compiler-rt-cdylib/compiler-rt/lib/builtins/%.S \
 	    $$(LLVM_CONFIG_$$(CFG_BUILD))
 	@mkdir -p $$(@D)
 	@$$(call E, compile: $$@)
diff --git a/mk/tests.mk b/mk/tests.mk
index fc1f4b5561a78..37dacce1a0cf1 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -22,8 +22,9 @@ $(eval $(call RUST_CRATE,coretest))
 DEPS_collectionstest :=
 $(eval $(call RUST_CRATE,collectionstest))
 
+# compiler_builtins is tested out of tree
 TEST_TARGET_CRATES = $(filter-out core rustc_unicode alloc_system libc \
-		     		  alloc_jemalloc panic_unwind \
+		     		  alloc_jemalloc panic_unwind compiler_builtins \
 				  panic_abort,$(TARGET_CRATES)) \
 			collectionstest coretest
 TEST_DOC_CRATES = $(DOC_CRATES) arena flate fmt_macros getopts graphviz \
diff --git a/src/Cargo.lock b/src/Cargo.lock
index a32ba02457edf..ac165b577c48c 100644
--- a/src/Cargo.lock
+++ b/src/Cargo.lock
@@ -84,6 +84,7 @@ version = "0.0.0"
 dependencies = [
  "core 0.0.0",
  "gcc 0.3.35 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-cfg 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -285,6 +286,11 @@ dependencies = [
  "syntax_pos 0.0.0",
 ]
 
+[[package]]
+name = "rustc-cfg"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "rustc-main"
 version = "0.0.0"
@@ -743,6 +749,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum matches 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "15305656809ce5a4805b1ff2946892810992197ce1270ff79baded852187942e"
 "checksum md5 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a5539a8dee9b4ae308c9c406a379838b435a8f2c84cf9fedc6d5a576be9888db"
 "checksum num_cpus 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)" = "cee7e88156f3f9e19bdd598f8d6c9db7bf4078f99f8381f43a55b09648d1a6e3"
+"checksum rustc-cfg 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "37937dfed502ccc4e644c3cc272222e31adc2b1f5d215f6f8f8e1a422072e516"
 "checksum rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)" = "6159e4e6e559c81bd706afe9c8fd68f547d3e851ce12e76b1de7914bab61691b"
 "checksum toml 0.1.30 (registry+https://github.com/rust-lang/crates.io-index)" = "0590d72182e50e879c4da3b11c6488dae18fccb1ae0c7a3eda18e16795844796"
 "checksum unicode-bidi 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "c1f7ceb96afdfeedee42bade65a0d585a6a0106f681b6749c8ff4daa8df30b3f"
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 12938b8326e79..0ce51d381c40f 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -578,8 +578,8 @@ impl Build {
                                   .args(&["clean", "-fdx"]));
                 },
                 State::NotInitialized => {
-                    self.run(git_submodule().arg("init").arg(submodule.path));
-                    self.run(git_submodule().arg("update").arg(submodule.path));
+                    self.run(git_submodule().arg("update").arg("--recursive").arg("--init")
+                             .arg(submodule.path));
                 },
                 State::OutOfSync => {
                     // drops submodule commits that weren't reported to the (outer) git repository
diff --git a/src/compiler-rt b/src/compiler-rt
deleted file mode 160000
index f03ba5a4e8bf1..0000000000000
--- a/src/compiler-rt
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit f03ba5a4e8bf16dcf42dd742a4ce255c36321356
diff --git a/src/libcompiler_builtins b/src/libcompiler_builtins
new file mode 160000
index 0000000000000..a163ca7ac3045
--- /dev/null
+++ b/src/libcompiler_builtins
@@ -0,0 +1 @@
+Subproject commit a163ca7ac30451475e568a77caeb53d0b9b1e879
diff --git a/src/libcompiler_builtins/Cargo.toml b/src/libcompiler_builtins/Cargo.toml
deleted file mode 100644
index a52873fc326b8..0000000000000
--- a/src/libcompiler_builtins/Cargo.toml
+++ /dev/null
@@ -1,15 +0,0 @@
-[package]
-authors = ["The Rust Project Developers"]
-build = "build.rs"
-name = "compiler_builtins"
-version = "0.0.0"
-
-[lib]
-name = "compiler_builtins"
-path = "lib.rs"
-
-[dependencies]
-core = { path = "../libcore" }
-
-[build-dependencies]
-gcc = "0.3.27"
diff --git a/src/libcompiler_builtins/build.rs b/src/libcompiler_builtins/build.rs
deleted file mode 100644
index acbd39bb1630c..0000000000000
--- a/src/libcompiler_builtins/build.rs
+++ /dev/null
@@ -1,410 +0,0 @@
-// Copyright 2016 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.
-
-//! Compiles the `compiler-rt` library, or at least the builtins part of it.
-//!
-//! Note that while compiler-rt has a build system associated with it, we
-//! specifically don't use it here. The compiler-rt build system, written in
-//! CMake, is actually *very* difficult to work with in terms of getting it to
-//! compile on all the relevant platforms we want it to compile on. In the end
-//! it became so much pain to work with local patches, work around the oddities
-//! of the build system, etc, that we're just building everything by hand now.
-//!
-//! In general compiler-rt is just a bunch of intrinsics that are in practice
-//! *very* stable. We just need to make sure that all the relevant functions and
-//! such are compiled somewhere and placed in an object file somewhere.
-//! Eventually, these should all be written in Rust!
-//!
-//! So below you'll find a listing of every single file in the compiler-rt repo
-//! that we're compiling. We just reach in and compile with the `gcc` crate
-//! which should have all the relevant flags and such already configured.
-//!
-//! The risk here is that if we update compiler-rt we may need to compile some
-//! new intrinsics, but to be honest we surely don't use all of the intrinsics
-//! listed below today so the likelihood of us actually needing a new intrinsic
-//! is quite low. The failure case is also just that someone reports a link
-//! error (if any) and then we just add it to the list. Overall, that cost is
-//! far far less than working with compiler-rt's build system over time.
-
-extern crate gcc;
-
-use std::collections::BTreeMap;
-use std::env;
-use std::path::Path;
-
-struct Sources {
-    // SYMBOL -> PATH TO SOURCE
-    map: BTreeMap<&'static str, &'static str>,
-}
-
-impl Sources {
-    fn new() -> Sources {
-        Sources { map: BTreeMap::new() }
-    }
-
-    fn extend(&mut self, sources: &[&'static str]) {
-        // NOTE Some intrinsics have both a generic implementation (e.g.
-        // `floatdidf.c`) and an arch optimized implementation
-        // (`x86_64/floatdidf.c`). In those cases, we keep the arch optimized
-        // implementation and discard the generic implementation. If we don't
-        // and keep both implementations, the linker will yell at us about
-        // duplicate symbols!
-        for &src in sources {
-            let symbol = Path::new(src).file_stem().unwrap().to_str().unwrap();
-            if src.contains("/") {
-                // Arch-optimized implementation (preferred)
-                self.map.insert(symbol, src);
-            } else {
-                // Generic implementation
-                if !self.map.contains_key(symbol) {
-                    self.map.insert(symbol, src);
-                }
-            }
-        }
-    }
-}
-
-fn main() {
-    let target = env::var("TARGET").expect("TARGET was not set");
-
-    // Emscripten's runtime includes all the builtins
-    if target.contains("emscripten") {
-        return;
-    }
-
-    let cfg = &mut gcc::Config::new();
-
-    if target.contains("msvc") {
-        // Don't pull in extra libraries on MSVC
-        cfg.flag("/Zl");
-
-        // Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP
-        cfg.define("__func__", Some("__FUNCTION__"));
-    } else {
-        // Turn off various features of gcc and such, mostly copying
-        // compiler-rt's build system already
-        cfg.flag("-fno-builtin");
-        cfg.flag("-fvisibility=hidden");
-        cfg.flag("-fomit-frame-pointer");
-        cfg.flag("-ffreestanding");
-    }
-
-    let mut sources = Sources::new();
-    sources.extend(&["absvdi2.c",
-                     "absvsi2.c",
-                     "adddf3.c",
-                     "addsf3.c",
-                     "addvdi3.c",
-                     "addvsi3.c",
-                     "apple_versioning.c",
-                     "ashldi3.c",
-                     "ashrdi3.c",
-                     "clear_cache.c",
-                     "clzdi2.c",
-                     "clzsi2.c",
-                     "cmpdi2.c",
-                     "comparedf2.c",
-                     "comparesf2.c",
-                     "ctzdi2.c",
-                     "ctzsi2.c",
-                     "divdc3.c",
-                     "divdf3.c",
-                     "divdi3.c",
-                     "divmoddi4.c",
-                     "divmodsi4.c",
-                     "divsc3.c",
-                     "divsf3.c",
-                     "divsi3.c",
-                     "divxc3.c",
-                     "extendsfdf2.c",
-                     "extendhfsf2.c",
-                     "ffsdi2.c",
-                     "fixdfdi.c",
-                     "fixdfsi.c",
-                     "fixsfdi.c",
-                     "fixsfsi.c",
-                     "fixunsdfdi.c",
-                     "fixunsdfsi.c",
-                     "fixunssfdi.c",
-                     "fixunssfsi.c",
-                     "fixunsxfdi.c",
-                     "fixunsxfsi.c",
-                     "fixxfdi.c",
-                     "floatdidf.c",
-                     "floatdisf.c",
-                     "floatdixf.c",
-                     "floatsidf.c",
-                     "floatsisf.c",
-                     "floatundidf.c",
-                     "floatundisf.c",
-                     "floatundixf.c",
-                     "floatunsidf.c",
-                     "floatunsisf.c",
-                     "int_util.c",
-                     "lshrdi3.c",
-                     "moddi3.c",
-                     "modsi3.c",
-                     "muldc3.c",
-                     "muldf3.c",
-                     "muldi3.c",
-                     "mulodi4.c",
-                     "mulosi4.c",
-                     "muloti4.c",
-                     "mulsc3.c",
-                     "mulsf3.c",
-                     "mulvdi3.c",
-                     "mulvsi3.c",
-                     "mulxc3.c",
-                     "negdf2.c",
-                     "negdi2.c",
-                     "negsf2.c",
-                     "negvdi2.c",
-                     "negvsi2.c",
-                     "paritydi2.c",
-                     "paritysi2.c",
-                     "popcountdi2.c",
-                     "popcountsi2.c",
-                     "powidf2.c",
-                     "powisf2.c",
-                     "powixf2.c",
-                     "subdf3.c",
-                     "subsf3.c",
-                     "subvdi3.c",
-                     "subvsi3.c",
-                     "truncdfhf2.c",
-                     "truncdfsf2.c",
-                     "truncsfhf2.c",
-                     "ucmpdi2.c",
-                     "udivdi3.c",
-                     "udivmoddi4.c",
-                     "udivmodsi4.c",
-                     "udivsi3.c",
-                     "umoddi3.c",
-                     "umodsi3.c"]);
-
-    if !target.contains("ios") {
-        sources.extend(&["absvti2.c",
-                         "addtf3.c",
-                         "addvti3.c",
-                         "ashlti3.c",
-                         "ashrti3.c",
-                         "clzti2.c",
-                         "cmpti2.c",
-                         "ctzti2.c",
-                         "divtf3.c",
-                         "divti3.c",
-                         "ffsti2.c",
-                         "fixdfti.c",
-                         "fixsfti.c",
-                         "fixunsdfti.c",
-                         "fixunssfti.c",
-                         "fixunsxfti.c",
-                         "fixxfti.c",
-                         "floattidf.c",
-                         "floattisf.c",
-                         "floattixf.c",
-                         "floatuntidf.c",
-                         "floatuntisf.c",
-                         "floatuntixf.c",
-                         "lshrti3.c",
-                         "modti3.c",
-                         "multf3.c",
-                         "multi3.c",
-                         "mulvti3.c",
-                         "negti2.c",
-                         "negvti2.c",
-                         "parityti2.c",
-                         "popcountti2.c",
-                         "powitf2.c",
-                         "subtf3.c",
-                         "subvti3.c",
-                         "trampoline_setup.c",
-                         "ucmpti2.c",
-                         "udivmodti4.c",
-                         "udivti3.c",
-                         "umodti3.c"]);
-    }
-
-    if target.contains("apple") {
-        sources.extend(&["atomic_flag_clear.c",
-                         "atomic_flag_clear_explicit.c",
-                         "atomic_flag_test_and_set.c",
-                         "atomic_flag_test_and_set_explicit.c",
-                         "atomic_signal_fence.c",
-                         "atomic_thread_fence.c"]);
-    }
-
-    if !target.contains("windows") {
-        sources.extend(&["emutls.c"]);
-    }
-
-    if target.contains("msvc") {
-        if target.contains("x86_64") {
-            sources.extend(&["x86_64/floatdidf.c", "x86_64/floatdisf.c", "x86_64/floatdixf.c"]);
-        }
-    } else {
-        if !target.contains("freebsd") {
-            sources.extend(&["gcc_personality_v0.c"]);
-        }
-
-        if target.contains("x86_64") {
-            sources.extend(&["x86_64/chkstk.S",
-                             "x86_64/chkstk2.S",
-                             "x86_64/floatdidf.c",
-                             "x86_64/floatdisf.c",
-                             "x86_64/floatdixf.c",
-                             "x86_64/floatundidf.S",
-                             "x86_64/floatundisf.S",
-                             "x86_64/floatundixf.S"]);
-        }
-
-        if target.contains("i386") || target.contains("i586") || target.contains("i686") {
-            sources.extend(&["i386/ashldi3.S",
-                             "i386/ashrdi3.S",
-                             "i386/chkstk.S",
-                             "i386/chkstk2.S",
-                             "i386/divdi3.S",
-                             "i386/floatdidf.S",
-                             "i386/floatdisf.S",
-                             "i386/floatdixf.S",
-                             "i386/floatundidf.S",
-                             "i386/floatundisf.S",
-                             "i386/floatundixf.S",
-                             "i386/lshrdi3.S",
-                             "i386/moddi3.S",
-                             "i386/muldi3.S",
-                             "i386/udivdi3.S",
-                             "i386/umoddi3.S"]);
-        }
-    }
-
-    if target.contains("arm") && !target.contains("ios") {
-        sources.extend(&["arm/aeabi_cdcmp.S",
-                         "arm/aeabi_cdcmpeq_check_nan.c",
-                         "arm/aeabi_cfcmp.S",
-                         "arm/aeabi_cfcmpeq_check_nan.c",
-                         "arm/aeabi_dcmp.S",
-                         "arm/aeabi_div0.c",
-                         "arm/aeabi_drsub.c",
-                         "arm/aeabi_fcmp.S",
-                         "arm/aeabi_frsub.c",
-                         "arm/aeabi_idivmod.S",
-                         "arm/aeabi_ldivmod.S",
-                         "arm/aeabi_memcmp.S",
-                         "arm/aeabi_memcpy.S",
-                         "arm/aeabi_memmove.S",
-                         "arm/aeabi_memset.S",
-                         "arm/aeabi_uidivmod.S",
-                         "arm/aeabi_uldivmod.S",
-                         "arm/bswapdi2.S",
-                         "arm/bswapsi2.S",
-                         "arm/clzdi2.S",
-                         "arm/clzsi2.S",
-                         "arm/comparesf2.S",
-                         "arm/divmodsi4.S",
-                         "arm/divsi3.S",
-                         "arm/modsi3.S",
-                         "arm/switch16.S",
-                         "arm/switch32.S",
-                         "arm/switch8.S",
-                         "arm/switchu8.S",
-                         "arm/sync_synchronize.S",
-                         "arm/udivmodsi4.S",
-                         "arm/udivsi3.S",
-                         "arm/umodsi3.S"]);
-    }
-
-    if target.contains("armv7") {
-        sources.extend(&["arm/sync_fetch_and_add_4.S",
-                         "arm/sync_fetch_and_add_8.S",
-                         "arm/sync_fetch_and_and_4.S",
-                         "arm/sync_fetch_and_and_8.S",
-                         "arm/sync_fetch_and_max_4.S",
-                         "arm/sync_fetch_and_max_8.S",
-                         "arm/sync_fetch_and_min_4.S",
-                         "arm/sync_fetch_and_min_8.S",
-                         "arm/sync_fetch_and_nand_4.S",
-                         "arm/sync_fetch_and_nand_8.S",
-                         "arm/sync_fetch_and_or_4.S",
-                         "arm/sync_fetch_and_or_8.S",
-                         "arm/sync_fetch_and_sub_4.S",
-                         "arm/sync_fetch_and_sub_8.S",
-                         "arm/sync_fetch_and_umax_4.S",
-                         "arm/sync_fetch_and_umax_8.S",
-                         "arm/sync_fetch_and_umin_4.S",
-                         "arm/sync_fetch_and_umin_8.S",
-                         "arm/sync_fetch_and_xor_4.S",
-                         "arm/sync_fetch_and_xor_8.S"]);
-    }
-
-    if target.contains("eabihf") {
-        sources.extend(&["arm/adddf3vfp.S",
-                         "arm/addsf3vfp.S",
-                         "arm/divdf3vfp.S",
-                         "arm/divsf3vfp.S",
-                         "arm/eqdf2vfp.S",
-                         "arm/eqsf2vfp.S",
-                         "arm/extendsfdf2vfp.S",
-                         "arm/fixdfsivfp.S",
-                         "arm/fixsfsivfp.S",
-                         "arm/fixunsdfsivfp.S",
-                         "arm/fixunssfsivfp.S",
-                         "arm/floatsidfvfp.S",
-                         "arm/floatsisfvfp.S",
-                         "arm/floatunssidfvfp.S",
-                         "arm/floatunssisfvfp.S",
-                         "arm/gedf2vfp.S",
-                         "arm/gesf2vfp.S",
-                         "arm/gtdf2vfp.S",
-                         "arm/gtsf2vfp.S",
-                         "arm/ledf2vfp.S",
-                         "arm/lesf2vfp.S",
-                         "arm/ltdf2vfp.S",
-                         "arm/ltsf2vfp.S",
-                         "arm/muldf3vfp.S",
-                         "arm/mulsf3vfp.S",
-                         "arm/negdf2vfp.S",
-                         "arm/negsf2vfp.S",
-                         "arm/nedf2vfp.S",
-                         "arm/nesf2vfp.S",
-                         "arm/restore_vfp_d8_d15_regs.S",
-                         "arm/save_vfp_d8_d15_regs.S",
-                         "arm/subdf3vfp.S",
-                         "arm/subsf3vfp.S",
-                         "arm/truncdfsf2vfp.S",
-                         "arm/unorddf2vfp.S",
-                         "arm/unordsf2vfp.S"]);
-    }
-
-    if target.contains("aarch64") {
-        sources.extend(&["comparetf2.c",
-                         "extenddftf2.c",
-                         "extendsftf2.c",
-                         "fixtfdi.c",
-                         "fixtfsi.c",
-                         "fixtfti.c",
-                         "fixunstfdi.c",
-                         "fixunstfsi.c",
-                         "fixunstfti.c",
-                         "floatditf.c",
-                         "floatsitf.c",
-                         "floatunditf.c",
-                         "floatunsitf.c",
-                         "multc3.c",
-                         "trunctfdf2.c",
-                         "trunctfsf2.c"]);
-    }
-
-    for src in sources.map.values() {
-        cfg.file(Path::new("../compiler-rt/lib/builtins").join(src));
-    }
-
-    cfg.compile("libcompiler-rt.a");
-}
diff --git a/src/libcompiler_builtins/lib.rs b/src/libcompiler_builtins/lib.rs
deleted file mode 100644
index 4a703b3da68f6..0000000000000
--- a/src/libcompiler_builtins/lib.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2016 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.
-
-#![feature(compiler_builtins)]
-#![no_std]
-#![compiler_builtins]
-#![unstable(feature = "compiler_builtins_lib",
-            reason = "internal implementation detail of rustc right now",
-            issue = "0")]
-#![crate_name = "compiler_builtins"]
-#![crate_type = "rlib"]
-#![feature(staged_api)]
diff --git a/src/libstd/Cargo.toml b/src/libstd/Cargo.toml
index 21e6acc37f3d5..cc65f1b7a4ebd 100644
--- a/src/libstd/Cargo.toml
+++ b/src/libstd/Cargo.toml
@@ -19,7 +19,7 @@ collections = { path = "../libcollections" }
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
 rand = { path = "../librand" }
-compiler_builtins = { path = "../libcompiler_builtins" }
+compiler_builtins = { path = "../rustc/libcompiler_builtins_shim" }
 rustc_unicode = { path = "../librustc_unicode" }
 unwind = { path = "../libunwind" }
 
diff --git a/src/rustc/libcompiler_builtins_shim/Cargo.toml b/src/rustc/libcompiler_builtins_shim/Cargo.toml
new file mode 100644
index 0000000000000..81c8a1ad742c7
--- /dev/null
+++ b/src/rustc/libcompiler_builtins_shim/Cargo.toml
@@ -0,0 +1,25 @@
+# This is a shim Cargo.toml over the "real Cargo.toml" found in the compiler-builtins
+# repository itself. See ../libc_shim/Cargo.toml for details
+
+[package]
+name = "compiler_builtins"
+version = "0.0.0"
+authors = ["The Rust Project Developers"]
+build = "../../libcompiler_builtins/build.rs"
+
+[lib]
+name = "compiler_builtins"
+path = "../../libcompiler_builtins/src/lib.rs"
+test = false
+
+[build-dependencies]
+gcc = "0.3.27"
+rustc-cfg = "0.2.0"
+
+[dependencies]
+core = { path = "../../libcore" }
+
+[features]
+default = ["c", "rustbuild"]
+c = []
+rustbuild = []