Index: libcxx/trunk/include/__config
===================================================================
--- libcxx/trunk/include/__config
+++ libcxx/trunk/include/__config
@@ -917,7 +917,7 @@
 #define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
 #endif
 
-// Thread-unsafe functions such as strtok(), mbtowc() and localtime()
+// Thread-unsafe functions such as strtok() and localtime()
 // are not available.
 #ifdef __CloudABI__
 #define _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
Index: libcxx/trunk/include/cstdlib
===================================================================
--- libcxx/trunk/include/cstdlib
+++ libcxx/trunk/include/cstdlib
@@ -144,11 +144,9 @@
 #ifndef _LIBCPP_HAS_NO_LONG_LONG
 using ::lldiv;
 #endif // _LIBCPP_HAS_NO_LONG_LONG
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
 using ::mblen;
 using ::mbtowc;
 using ::wctomb;
-#endif
 using ::mbstowcs;
 using ::wcstombs;
 #ifdef _LIBCPP_HAS_QUICK_EXIT
Index: libcxx/trunk/test/std/depr/depr.c.headers/stdlib_h.pass.cpp
===================================================================
--- libcxx/trunk/test/std/depr/depr.c.headers/stdlib_h.pass.cpp
+++ libcxx/trunk/test/std/depr/depr.c.headers/stdlib_h.pass.cpp
@@ -104,11 +104,9 @@
     wchar_t* pw = 0;
     const wchar_t* pwc = 0;
     char* pc = 0;
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
     static_assert((std::is_same<decltype(mblen("",0)), int>::value), "");
     static_assert((std::is_same<decltype(mbtowc(pw,"",0)), int>::value), "");
     static_assert((std::is_same<decltype(wctomb(pc,L' ')), int>::value), "");
-#endif
     static_assert((std::is_same<decltype(mbstowcs(pw,"",0)), size_t>::value), "");
     static_assert((std::is_same<decltype(wcstombs(pc,pwc,0)), size_t>::value), "");
 }
Index: libcxx/trunk/test/std/language.support/support.runtime/cstdlib.pass.cpp
===================================================================
--- libcxx/trunk/test/std/language.support/support.runtime/cstdlib.pass.cpp
+++ libcxx/trunk/test/std/language.support/support.runtime/cstdlib.pass.cpp
@@ -96,11 +96,9 @@
     wchar_t* pw = 0;
     const wchar_t* pwc = 0;
     char* pc = 0;
-#ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
     static_assert((std::is_same<decltype(std::mblen("",0)), int>::value), "");
     static_assert((std::is_same<decltype(std::mbtowc(pw,"",0)), int>::value), "");
     static_assert((std::is_same<decltype(std::wctomb(pc,L' ')), int>::value), "");
-#endif
     static_assert((std::is_same<decltype(std::mbstowcs(pw,"",0)), std::size_t>::value), "");
     static_assert((std::is_same<decltype(std::wcstombs(pc,pwc,0)), std::size_t>::value), "");
 }