Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -29,6 +29,7 @@
 check_cxx_compiler_flag(-ftls-model=initial-exec COMPILER_RT_HAS_FTLS_MODEL_INITIAL_EXEC)
 check_cxx_compiler_flag(-fno-lto             COMPILER_RT_HAS_FNO_LTO_FLAG)
 check_cxx_compiler_flag("-Werror -msse3" COMPILER_RT_HAS_MSSE3_FLAG)
+check_cxx_compiler_flag("-Werror -msse4.2"   COMPILER_RT_HAS_MSSE4_2_FLAG)
 check_cxx_compiler_flag(--sysroot=.          COMPILER_RT_HAS_SYSROOT_FLAG)
 
 if(NOT WIN32 AND NOT CYGWIN)
Index: lib/scudo/CMakeLists.txt
===================================================================
--- lib/scudo/CMakeLists.txt
+++ lib/scudo/CMakeLists.txt
@@ -3,16 +3,23 @@
 include_directories(..)
 
 set(SCUDO_CFLAGS ${SANITIZER_COMMON_CFLAGS})
+# SANITIZER_COMMON_CFLAGS include -fno-builtin, but we actually want builtins!
+list(APPEND SCUDO_CFLAGS -fbuiltin)
 append_rtti_flag(OFF SCUDO_CFLAGS)
 
 set(SCUDO_SOURCES
   scudo_allocator.cpp
   scudo_flags.cpp
+  scudo_crc32.cpp
   scudo_interceptors.cpp
   scudo_new_delete.cpp
   scudo_termination.cpp
   scudo_utils.cpp)
 
+if (COMPILER_RT_HAS_MSSE4_2_FLAG)
+  set_source_files_properties(scudo_crc32.cpp PROPERTIES COMPILE_FLAGS -msse4.2)
+endif()
+
 if(COMPILER_RT_HAS_SCUDO)
   foreach(arch ${SCUDO_SUPPORTED_ARCH})
     add_compiler_rt_runtime(clang_rt.scudo
Index: lib/scudo/scudo_allocator.cpp
===================================================================
--- lib/scudo/scudo_allocator.cpp
+++ lib/scudo/scudo_allocator.cpp
@@ -15,6 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "scudo_allocator.h"
+#include "scudo_crc32.h"
 #include "scudo_utils.h"
 
 #include "sanitizer_common/sanitizer_allocator_interface.h"
@@ -25,22 +26,6 @@
 
 #include <cstring>
 
-// Hardware CRC32 is supported at compilation via the following:
-// - for i386 & x86_64: -msse4.2
-// - for ARM & AArch64: -march=armv8-a+crc
-// An additional check must be performed at runtime as well to make sure the
-// emitted instructions are valid on the target host.
-#if defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
-# ifdef __SSE4_2__
-#  include <smmintrin.h>
-#  define HW_CRC32 FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64)
-# endif
-# ifdef __ARM_FEATURE_CRC32
-#  include <arm_acle.h>
-#  define HW_CRC32 FIRST_32_SECOND_64(__crc32cw, __crc32cd)
-# endif
-#endif
-
 namespace __scudo {
 
 #if SANITIZER_CAN_USE_ALLOCATOR64
@@ -84,10 +69,6 @@
 // Global static cookie, initialized at start-up.
 static uptr Cookie;
 
-enum : u8 {
-  CRC32Software = 0,
-  CRC32Hardware = 1,
-};
 // We default to software CRC32 if the alternatives are not supported, either
 // at compilation or at runtime.
 static atomic_uint8_t HashAlgorithm = { CRC32Software };
@@ -97,17 +78,9 @@
 // the checksumming function if available.
 INLINE u32 hashUptrs(uptr Pointer, uptr *Array, uptr ArraySize, u8 HashType) {
   u32 Crc;
-#if defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
-  if (HashType == CRC32Hardware) {
-    Crc = HW_CRC32(Cookie, Pointer);
-    for (uptr i = 0; i < ArraySize; i++)
-      Crc = HW_CRC32(Crc, Array[i]);
-    return Crc;
-  }
-#endif
-  Crc = computeCRC32(Cookie, Pointer);
+  Crc = computeCRC32(Cookie, Pointer, HashType);
   for (uptr i = 0; i < ArraySize; i++)
-    Crc = computeCRC32(Crc, Array[i]);
+    Crc = computeCRC32(Crc, Array[i], HashType);
   return Crc;
 }
 
Index: lib/scudo/scudo_crc32.h
===================================================================
--- /dev/null
+++ lib/scudo/scudo_crc32.h
@@ -0,0 +1,30 @@
+//===-- scudo_crc32.h -------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// Header for scudo_crc32.cpp.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef SCUDO_CRC32_H_
+#define SCUDO_CRC32_H_
+
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
+namespace __scudo {
+
+enum : u8 {
+  CRC32Software = 0,
+  CRC32Hardware = 1,
+};
+
+u32 computeCRC32(u32 Crc, uptr Data, u8 HashType);
+
+}  // namespace __scudo
+
+#endif  // SCUDO_CRC32_H_
Index: lib/scudo/scudo_crc32.cpp
===================================================================
--- /dev/null
+++ lib/scudo/scudo_crc32.cpp
@@ -0,0 +1,53 @@
+//===-- scudo_crc32.cpp -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// CRC32 function leveraging hardware specific instructions. This has to be
+/// kept separated to restrict the use of compiler specific flags to this file.
+///
+//===----------------------------------------------------------------------===//
+
+// Hardware CRC32 is supported at compilation via the following:
+// - for i386 & x86_64: -msse4.2
+// - for ARM & AArch64: -march=armv8-a+crc or -mcrc
+// An additional check must be performed at runtime as well to make sure the
+// emitted instructions are valid on the target host.
+#include "scudo_crc32.h"
+#include "scudo_utils.h"
+
+#if defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
+# ifdef __SSE4_2__
+#  include <smmintrin.h>
+#  define CRC32_INTRINSIC FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64)
+# endif
+# ifdef __ARM_FEATURE_CRC32
+#  include <arm_acle.h>
+#  define CRC32_INTRINSIC FIRST_32_SECOND_64(__crc32cw, __crc32cd)
+# endif
+#endif  // defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
+
+namespace __scudo {
+
+#if defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
+INLINE u32 computeHardwareCRC32(u32 Crc, uptr Data) {
+  return CRC32_INTRINSIC(Crc, Data);
+}
+
+u32 computeCRC32(u32 Crc, uptr Data, u8 HashType) {
+  if (HashType == CRC32Hardware) {
+    return computeHardwareCRC32(Crc, Data);
+  }
+  return computeSoftwareCRC32(Crc, Data);
+}
+#else
+u32 computeCRC32(u32 Crc, uptr Data, u8 HashType) {
+  return computeSoftwareCRC32(Crc, Data);
+}
+#endif  // defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
+
+}  // namespace __scudo
Index: lib/scudo/scudo_utils.h
===================================================================
--- lib/scudo/scudo_utils.h
+++ lib/scudo/scudo_utils.h
@@ -53,8 +53,8 @@
   u64 State[2];
 };
 
-// Software CRC32 functions, to be used when SSE 4.2 support is not detected.
-u32 computeCRC32(u32 Crc, uptr Data);
+// Software CRC32 functions, to be used when hardware support is not detected.
+u32 computeSoftwareCRC32(u32 Crc, uptr Data);
 
 }  // namespace __scudo
 
Index: lib/scudo/scudo_utils.cpp
===================================================================
--- lib/scudo/scudo_utils.cpp
+++ lib/scudo/scudo_utils.cpp
@@ -185,8 +185,7 @@
   0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
 };
 
-u32 computeCRC32(u32 Crc, uptr Data)
-{
+u32 computeSoftwareCRC32(u32 Crc, uptr Data) {
   for (uptr i = 0; i < sizeof(Data); i++) {
     Crc = CRC32Table[(Crc ^ Data) & 0xff] ^ (Crc >> 8);
     Data >>= 8;