diff --git a/libcxx/include/__locale b/libcxx/include/__locale
--- a/libcxx/include/__locale
+++ b/libcxx/include/__locale
@@ -44,6 +44,8 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_runtime_error(const char*);
+
 #if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
 struct __libcpp_locale_guard {
   _LIBCPP_INLINE_VISIBILITY
@@ -1229,8 +1231,6 @@
 _LIBCPP_EXTERN_TEMPLATE2(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char, mbstate_t>)
 _LIBCPP_EXTERN_TEMPLATE2(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char32_t, char, mbstate_t>)
 
-_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_runtime_error(const char*);
-
 template <size_t _Np>
 struct __narrow_to_utf8
 {
diff --git a/libcxx/include/stdexcept b/libcxx/include/stdexcept
--- a/libcxx/include/stdexcept
+++ b/libcxx/include/stdexcept
@@ -181,9 +181,6 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-// in the dylib
-_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_runtime_error(const char*);
-
 _LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
 void __throw_logic_error(const char*__msg)
 {