diff --git a/libcxx/test/support/msvc_stdlib_force_include.h b/libcxx/test/support/msvc_stdlib_force_include.h
--- a/libcxx/test/support/msvc_stdlib_force_include.h
+++ b/libcxx/test/support/msvc_stdlib_force_include.h
@@ -104,4 +104,8 @@
     __pragma(warning(pop))
 #endif // __clang__
 
+#if defined(_MSVC_EXECUTION_CHARACTER_SET) && _MSVC_EXECUTION_CHARACTER_SET != 65001
+#define _LIBCPP_HAS_NO_UNICODE 1
+#endif // defined(_MSVC_EXECUTION_CHARACTER_SET) && _MSVC_EXECUTION_CHARACTER_SET != 65001
+
 #endif // SUPPORT_MSVC_STDLIB_FORCE_INCLUDE_H