Index: cmake/config-ix.cmake
===================================================================
--- cmake/config-ix.cmake
+++ cmake/config-ix.cmake
@@ -28,8 +28,6 @@
 check_cxx_compiler_flag(-std=c++11           COMPILER_RT_HAS_STD_CXX11_FLAG)
 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
@@ -4,7 +4,6 @@
 
 set(SCUDO_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF SCUDO_CFLAGS)
-append_list_if(COMPILER_RT_HAS_MSSE4_2_FLAG -msse4.2 SCUDO_CFLAGS)
 
 set(SCUDO_SOURCES
   scudo_allocator.cpp
Index: lib/tsan/CMakeLists.txt
===================================================================
--- lib/tsan/CMakeLists.txt
+++ lib/tsan/CMakeLists.txt
@@ -16,7 +16,6 @@
 endif()
 
 set(TSAN_RTL_CFLAGS ${TSAN_CFLAGS})
-append_list_if(COMPILER_RT_HAS_MSSE3_FLAG -msse3 TSAN_RTL_CFLAGS)
 append_list_if(SANITIZER_LIMIT_FRAME_SIZE -Wframe-larger-than=530
                TSAN_RTL_CFLAGS)
 append_list_if(COMPILER_RT_HAS_WGLOBAL_CONSTRUCTORS_FLAG -Wglobal-constructors