Index: include/functional
===================================================================
--- include/functional
+++ include/functional
@@ -1006,7 +1006,7 @@
 {
     _Predicate __pred_;
 public:
-    _LIBCPP_INLINE_VISIBILITY explicit _LIBCPP_CONSTEXPR_AFTER_CXX11 
+    _LIBCPP_INLINE_VISIBILITY explicit _LIBCPP_CONSTEXPR_AFTER_CXX11
     binary_negate(const _Predicate& __pred) : __pred_(__pred) {}
 
     _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
@@ -1793,7 +1793,7 @@
         typedef __function::__func<_Fp, _Alloc, _Rp(_ArgTypes...)> _FF;
         typedef typename __rebind_alloc_helper<__alloc_traits, _FF>::type _Ap;
         _Ap __a(__a0);
-        if (sizeof(_FF) <= sizeof(__buf_) && 
+        if (sizeof(_FF) <= sizeof(__buf_) &&
             is_nothrow_copy_constructible<_Fp>::value && is_nothrow_copy_constructible<_Ap>::value)
         {
             __f_ = ::new((void*)&__buf_) _FF(_VSTD::move(__f), _Alloc(__a));
@@ -2254,7 +2254,11 @@
 
     template <class ..._Args>
         _LIBCPP_INLINE_VISIBILITY
+#ifndef __cpp_decltype_auto
         typename __bind_return<_Fd, _Td, tuple<_Args&&...> >::type
+#else
+        decltype(auto)
+#endif
         operator()(_Args&& ...__args)
         {
             return __apply_functor(__f_, __bound_args_, __indices(),
@@ -2263,7 +2267,11 @@
 
     template <class ..._Args>
         _LIBCPP_INLINE_VISIBILITY
+#ifndef __cpp_decltype_auto
         typename __bind_return<const _Fd, const _Td, tuple<_Args&&...> >::type
+#else
+        decltype(auto)
+#endif
         operator()(_Args&& ...__args) const
         {
             return __apply_functor(__f_, __bound_args_, __indices(),