Index: lib/scudo/standalone/CMakeLists.txt
===================================================================
--- lib/scudo/standalone/CMakeLists.txt
+++ lib/scudo/standalone/CMakeLists.txt
@@ -6,9 +6,14 @@
 
 list(APPEND SCUDO_CFLAGS
   -Wall
-  -Werror
   -nostdinc++)
 
+# Do not error out on spurious flags. They can be passed via CMAKE_CXX_FLAGS
+# for example, so we have very little control on those.
+if(COMPILER_RT_ENABLE_WERROR)
+  append_string_if(COMPILER_RT_HAS_WERROR_FLAG -Wno-unused-command-line-argument SCUDO_CFLAGS)
+endif()
+
 append_list_if(COMPILER_RT_HAS_FFREESTANDING_FLAG -ffreestanding SCUDO_CFLAGS)
 
 append_list_if(COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG -fvisibility=hidden SCUDO_CFLAGS)