Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -176,6 +176,8 @@
 # always respect the optimization flags set by CMAKE_BUILD_TYPE instead.
 if(NOT COMPILER_RT_DEBUG AND NOT MSVC)
   list(APPEND SANITIZER_COMMON_CFLAGS -O3)
+else()
+  list(APPEND SANITIZER_COMMON_CFLAGS -O0)
 endif()
 
 # Determine if we should restrict stack frame sizes.