diff --git a/libcxx/include/__availability b/libcxx/include/__availability
--- a/libcxx/include/__availability
+++ b/libcxx/include/__availability
@@ -174,6 +174,12 @@
 // #   define _LIBCPP_AVAILABILITY_HAS_NO_PMR
 #   define _LIBCPP_AVAILABILITY_PMR
 
+// 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.
+#   define _LIBCPP_AVAILABILITY_ENABLE_BAD_FUNCTION_CALL_KEY_FUNCTION
+#   define _LIBCPP_AVAILABILITY_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
+
 #elif defined(__APPLE__)
 
     // shared_mutex and shared_timed_mutex
diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -102,10 +102,6 @@
 #    define _LIBCPP_ABI_FIX_UNORDERED_NODE_POINTER_UB
 #    define _LIBCPP_ABI_FORWARD_LIST_REMOVE_NODE_POINTER_UB
 #    define _LIBCPP_ABI_FIX_UNORDERED_CONTAINER_SIZE_TYPE
-// 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.
-#    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
 // 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
@@ -173,24 +169,6 @@
 #    if defined(__FreeBSD__)
 #      define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #    endif
-// For XCOFF linkers, we have problems if we see a weak hidden version of a symbol
-// in user code (like you get with -fvisibility-inlines-hidden) and then a strong def
-// in the library, so we need to always rely on the library version.
-#    if defined(_AIX)
-#      define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
-#    endif
-#  endif
-
-#  if defined(_LIBCPP_BUILDING_LIBRARY) || _LIBCPP_ABI_VERSION >= 2
-// Enable additional explicit instantiations of iostreams components. This
-// reduces the number of weak definitions generated in programs that use
-// iostreams by providing a single strong definition in the shared library.
-#    define _LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
-
-// 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.
-#    define _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
 #  endif
 
 // Changes the iterator type of select containers (see below) to a bounded iterator that keeps track of whether it's
diff --git a/libcxx/include/__functional/function.h b/libcxx/include/__functional/function.h
--- a/libcxx/include/__functional/function.h
+++ b/libcxx/include/__functional/function.h
@@ -60,7 +60,7 @@
 // Note that when a key function is not used, every translation unit that uses
 // bad_function_call will end up containing a weak definition of the vtable and
 // typeinfo.
-#ifdef _LIBCPP_ABI_BAD_FUNCTION_CALL_KEY_FUNCTION
+#ifdef _LIBCPP_AVAILABILITY_ENABLE_BAD_FUNCTION_CALL_KEY_FUNCTION
     ~bad_function_call() _NOEXCEPT override;
 #else
     _LIBCPP_HIDE_FROM_ABI_VIRTUAL ~bad_function_call() _NOEXCEPT override {}
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -1734,7 +1734,7 @@
         this->setstate(ios_base::failbit);
 }
 
-#if defined(_LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
+#if defined(_LIBCPP_AVAILABILITY_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ifstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ofstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_filebuf<char>;
diff --git a/libcxx/include/sstream b/libcxx/include/sstream
--- a/libcxx/include/sstream
+++ b/libcxx/include/sstream
@@ -1013,7 +1013,7 @@
     __x.swap(__y);
 }
 
-#if defined(_LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
+#if defined(_LIBCPP_AVAILABILITY_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringbuf<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostringstream<char>;