diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 751903070051..f3a4d5833649 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -29,6 +29,7 @@ check_cxx_compiler_flag(-ftls-model=initial-exec COMPILER_RT_HAS_FTLS_MODEL_INIT
 check_cxx_compiler_flag(-fno-lto             COMPILER_RT_HAS_FNO_LTO_FLAG)
 check_cxx_compiler_flag(-msse3               COMPILER_RT_HAS_MSSE3_FLAG)
 check_cxx_compiler_flag(-std=c99             COMPILER_RT_HAS_STD_C99_FLAG)
+check_cxx_compiler_flag(--sysroot=.          COMPILER_RT_HAS_SYSROOT_FLAG)
 
 if(NOT WIN32 AND NOT CYGWIN)
   # MinGW warns if -fvisibility-inlines-hidden is used.
diff --git a/compiler-rt/lib/tsan/CMakeLists.txt b/compiler-rt/lib/tsan/CMakeLists.txt
index 34f6e30dee6c..5e480d9abbde 100644
--- a/compiler-rt/lib/tsan/CMakeLists.txt
+++ b/compiler-rt/lib/tsan/CMakeLists.txt
@@ -21,7 +21,6 @@ append_list_if(SANITIZER_LIMIT_FRAME_SIZE -Wframe-larger-than=512
                TSAN_RTL_CFLAGS)
 append_list_if(COMPILER_RT_HAS_WGLOBAL_CONSTRUCTORS_FLAG -Wglobal-constructors
                TSAN_RTL_CFLAGS)
-# FIXME: Add support for --sysroot=. compile flag:
 
 set(TSAN_SOURCES
   rtl/tsan_clock.cc
@@ -187,6 +186,18 @@ endif()
 
 add_dependencies(compiler-rt tsan)
 
+# Make sure that non-platform-specific files don't include any system headers.
+if(COMPILER_RT_HAS_SYSROOT_FLAG)
+  file(GLOB _tsan_generic_sources rtl/tsan*)
+  file(GLOB _tsan_platform_sources rtl/tsan*posix* rtl/tsan*mac*
+                                   rtl/tsan*linux*)
+  list(REMOVE_ITEM _tsan_generic_sources ${_tsan_platform_sources})
+  message(STATUS "platform: ${_tsan_platform_sources}")
+  message(STATUS "generic: ${_tsan_generic_sources}")
+  set_source_files_properties(${_tsan_generic_sources}
+    PROPERTIES COMPILE_FLAGS "--sysroot=.")
+endif()
+
 # Build libcxx instrumented with TSan.
 if(COMPILER_RT_HAS_LIBCXX_SOURCES AND
    COMPILER_RT_TEST_COMPILER_ID STREQUAL "Clang")