diff --git a/include/__config b/include/__config
index 10de952e7..3853916a0 100644
--- a/include/__config
+++ b/include/__config
@@ -1012,10 +1012,16 @@ _LIBCPP_FUNC_VIS extern "C" void __sanitizer_annotate_contiguous_container(
 #define _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
 #endif
 
-#if (defined(_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS) && defined(__clang__) \
-      && __has_attribute(acquire_capability))
+#if defined(_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS)
+#if defined(__clang__) && __has_attribute(acquire_capability)
+// Work around the attribute handling in clang.  When both __declspec and
+// __attribute__ are present, the processing goes awry preventing the definition
+// of the types.
+#if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
 #define _LIBCPP_HAS_THREAD_SAFETY_ANNOTATIONS
 #endif
+#endif
+#endif
 
 #if __has_attribute(require_constant_initialization)
 #define _LIBCPP_SAFE_STATIC __attribute__((__require_constant_initialization__))