diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -96,7 +96,9 @@
 // Define a key function for `bad_function_call` in the library, to centralize
 // its vtable and typeinfo to libc++ rather than having all other libraries
 // using that class define their own copies.
+# if defined(_AIX) & defined(_LIBCPP_BUILDING_LIBRARY)
 #    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+# endif
 // Override the default return value of exception::what() for
 // bad_function_call::what() with a string that is specific to
 // bad_function_call (see http://wg21.link/LWG2233). This is an ABI break
@@ -166,8 +168,11 @@
 // Define a key function for `bad_function_call` in the library, to centralize
 // its vtable and typeinfo to libc++ rather than having all other libraries
 // using that class define their own copies.
+#  if defined(_AIX) & defined(_LIBCPP_BUILDING_LIBRARY)
 #    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
 #  endif
+#  endif
+
 
 #  define _LIBCPP_TOSTRING2(x) #x
 #  define _LIBCPP_TOSTRING(x) _LIBCPP_TOSTRING2(x)