diff --git a/libcxx/include/__functional/bind.h b/libcxx/include/__functional/bind.h
--- a/libcxx/include/__functional/bind.h
+++ b/libcxx/include/__functional/bind.h
@@ -97,7 +97,7 @@
 
 template <class _Ti, class ..._Uj>
 inline _LIBCPP_INLINE_VISIBILITY
-typename _EnableIf
+typename __enable_if_t
 <
     is_bind_expression<_Ti>::value,
     __invoke_of<_Ti&, _Uj...>
diff --git a/libcxx/include/__functional/reference_wrapper.h b/libcxx/include/__functional/reference_wrapper.h
--- a/libcxx/include/__functional/reference_wrapper.h
+++ b/libcxx/include/__functional/reference_wrapper.h
@@ -46,7 +46,7 @@
     reference_wrapper(type& __f) _NOEXCEPT
         : __f_(_VSTD::addressof(__f)) {}
 #else
-    template <class _Up, class = _EnableIf<!__is_same_uncvref<_Up, reference_wrapper>::value, decltype(__fun(declval<_Up>())) >>
+    template <class _Up, class = __enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, decltype(__fun(declval<_Up>())) >>
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     reference_wrapper(_Up&& __u) _NOEXCEPT_(noexcept(__fun(declval<_Up>()))) {
         type& __f = static_cast<_Up&&>(__u);
diff --git a/libcxx/include/__iterator/advance.h b/libcxx/include/__iterator/advance.h
--- a/libcxx/include/__iterator/advance.h
+++ b/libcxx/include/__iterator/advance.h
@@ -55,7 +55,7 @@
 template <
     class _InputIter, class _Distance,
     class _IntegralDistance = decltype(_VSTD::__convert_to_integral(declval<_Distance>())),
-    class = _EnableIf<is_integral<_IntegralDistance>::value> >
+    class = __enable_if_t<is_integral<_IntegralDistance>::value> >
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX14
 void advance(_InputIter& __i, _Distance __orig_n) {
   typedef typename iterator_traits<_InputIter>::difference_type _Difference;
diff --git a/libcxx/include/__iterator/iterator_traits.h b/libcxx/include/__iterator/iterator_traits.h
--- a/libcxx/include/__iterator/iterator_traits.h
+++ b/libcxx/include/__iterator/iterator_traits.h
@@ -76,7 +76,7 @@
 };
 struct __iter_concept_random_fallback {
   template <class _Iter>
-  using _Apply = _EnableIf<
+  using _Apply = __enable_if_t<
                           __is_primary_template<iterator_traits<_Iter> >::value,
                           random_access_iterator_tag
                         >;
diff --git a/libcxx/include/__iterator/move_iterator.h b/libcxx/include/__iterator/move_iterator.h
--- a/libcxx/include/__iterator/move_iterator.h
+++ b/libcxx/include/__iterator/move_iterator.h
@@ -54,13 +54,13 @@
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
     explicit move_iterator(_Iter __x) : __i(__x) {}
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value && is_convertible<_Up const&, _Iter>::value
     > >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
     move_iterator(const move_iterator<_Up>& __u) : __i(__u.base()) {}
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value &&
         is_convertible<_Up const&, _Iter>::value &&
         is_assignable<_Iter&, _Up const&>::value
diff --git a/libcxx/include/__iterator/reverse_iterator.h b/libcxx/include/__iterator/reverse_iterator.h
--- a/libcxx/include/__iterator/reverse_iterator.h
+++ b/libcxx/include/__iterator/reverse_iterator.h
@@ -75,7 +75,7 @@
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
     explicit reverse_iterator(_Iter __x) : __t(__x), current(__x) {}
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value && is_convertible<_Up const&, _Iter>::value
     > >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
@@ -83,7 +83,7 @@
         : __t(__u.base()), current(__u.base())
     { }
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value &&
         is_convertible<_Up const&, _Iter>::value &&
         is_assignable<_Up const&, _Iter>::value
@@ -100,7 +100,7 @@
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
     explicit reverse_iterator(_Iter __x) : current(__x) {}
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value && is_convertible<_Up const&, _Iter>::value
     > >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
@@ -108,7 +108,7 @@
         : current(__u.base())
     { }
 
-    template <class _Up, class = _EnableIf<
+    template <class _Up, class = __enable_if_t<
         !is_same<_Up, _Iter>::value &&
         is_convertible<_Up const&, _Iter>::value &&
         is_assignable<_Up const&, _Iter>::value
diff --git a/libcxx/include/__memory/allocator_traits.h b/libcxx/include/__memory/allocator_traits.h
--- a/libcxx/include/__memory/allocator_traits.h
+++ b/libcxx/include/__memory/allocator_traits.h
@@ -263,7 +263,7 @@
     }
 
     template <class _Ap = _Alloc, class =
-        _EnableIf<__has_allocate_hint<_Ap, size_type, const_void_pointer>::value> >
+        __enable_if_t<__has_allocate_hint<_Ap, size_type, const_void_pointer>::value> >
     _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer __hint) {
         _LIBCPP_SUPPRESS_DEPRECATED_PUSH
@@ -271,7 +271,7 @@
         _LIBCPP_SUPPRESS_DEPRECATED_POP
     }
     template <class _Ap = _Alloc, class = void, class =
-        _EnableIf<!__has_allocate_hint<_Ap, size_type, const_void_pointer>::value> >
+        __enable_if_t<!__has_allocate_hint<_Ap, size_type, const_void_pointer>::value> >
     _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static pointer allocate(allocator_type& __a, size_type __n, const_void_pointer) {
         return __a.allocate(__n);
@@ -283,7 +283,7 @@
     }
 
     template <class _Tp, class... _Args, class =
-        _EnableIf<__has_construct<allocator_type, _Tp*, _Args...>::value> >
+        __enable_if_t<__has_construct<allocator_type, _Tp*, _Args...>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static void construct(allocator_type& __a, _Tp* __p, _Args&&... __args) {
         _LIBCPP_SUPPRESS_DEPRECATED_PUSH
@@ -291,7 +291,7 @@
         _LIBCPP_SUPPRESS_DEPRECATED_POP
     }
     template <class _Tp, class... _Args, class = void, class =
-        _EnableIf<!__has_construct<allocator_type, _Tp*, _Args...>::value> >
+        __enable_if_t<!__has_construct<allocator_type, _Tp*, _Args...>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static void construct(allocator_type&, _Tp* __p, _Args&&... __args) {
 #if _LIBCPP_STD_VER > 17
@@ -302,7 +302,7 @@
     }
 
     template <class _Tp, class =
-        _EnableIf<__has_destroy<allocator_type, _Tp*>::value> >
+        __enable_if_t<__has_destroy<allocator_type, _Tp*>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static void destroy(allocator_type& __a, _Tp* __p) {
         _LIBCPP_SUPPRESS_DEPRECATED_PUSH
@@ -310,7 +310,7 @@
         _LIBCPP_SUPPRESS_DEPRECATED_POP
     }
     template <class _Tp, class = void, class =
-        _EnableIf<!__has_destroy<allocator_type, _Tp*>::value> >
+        __enable_if_t<!__has_destroy<allocator_type, _Tp*>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static void destroy(allocator_type&, _Tp* __p) {
 #if _LIBCPP_STD_VER > 17
@@ -321,7 +321,7 @@
     }
 
     template <class _Ap = _Alloc, class =
-        _EnableIf<__has_max_size<const _Ap>::value> >
+        __enable_if_t<__has_max_size<const _Ap>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static size_type max_size(const allocator_type& __a) _NOEXCEPT {
         _LIBCPP_SUPPRESS_DEPRECATED_PUSH
@@ -329,20 +329,20 @@
         _LIBCPP_SUPPRESS_DEPRECATED_POP
     }
     template <class _Ap = _Alloc, class = void, class =
-        _EnableIf<!__has_max_size<const _Ap>::value> >
+        __enable_if_t<!__has_max_size<const _Ap>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static size_type max_size(const allocator_type&) _NOEXCEPT {
         return numeric_limits<size_type>::max() / sizeof(value_type);
     }
 
     template <class _Ap = _Alloc, class =
-        _EnableIf<__has_select_on_container_copy_construction<const _Ap>::value> >
+        __enable_if_t<__has_select_on_container_copy_construction<const _Ap>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static allocator_type select_on_container_copy_construction(const allocator_type& __a) {
         return __a.select_on_container_copy_construction();
     }
     template <class _Ap = _Alloc, class = void, class =
-        _EnableIf<!__has_select_on_container_copy_construction<const _Ap>::value> >
+        __enable_if_t<!__has_select_on_container_copy_construction<const _Ap>::value> >
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     static allocator_type select_on_container_copy_construction(const allocator_type& __a) {
         return __a;
@@ -374,7 +374,7 @@
 { };
 
 template <class _Alloc>
-struct __is_cpp17_move_insertable<_Alloc, _EnableIf<
+struct __is_cpp17_move_insertable<_Alloc, __enable_if_t<
     !__is_default_allocator<_Alloc>::value &&
     __has_construct<_Alloc, typename _Alloc::value_type*, typename _Alloc::value_type&&>::value
 > > : true_type { };
@@ -389,7 +389,7 @@
 { };
 
 template <class _Alloc>
-struct __is_cpp17_copy_insertable<_Alloc, _EnableIf<
+struct __is_cpp17_copy_insertable<_Alloc, __enable_if_t<
     !__is_default_allocator<_Alloc>::value &&
     __has_construct<_Alloc, typename _Alloc::value_type*, const typename _Alloc::value_type&>::value
 > >
diff --git a/libcxx/include/__memory/pointer_traits.h b/libcxx/include/__memory/pointer_traits.h
--- a/libcxx/include/__memory/pointer_traits.h
+++ b/libcxx/include/__memory/pointer_traits.h
@@ -173,7 +173,7 @@
 }
 
 // enable_if is needed here to avoid instantiating checks for fancy pointers on raw pointers
-template <class _Pointer, class = _EnableIf<
+template <class _Pointer, class = __enable_if_t<
     !is_pointer<_Pointer>::value && !is_array<_Pointer>::value && !is_function<_Pointer>::value
 > >
 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
diff --git a/libcxx/include/__memory/shared_ptr.h b/libcxx/include/__memory/shared_ptr.h
--- a/libcxx/include/__memory/shared_ptr.h
+++ b/libcxx/include/__memory/shared_ptr.h
@@ -437,7 +437,7 @@
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR shared_ptr(nullptr_t) _NOEXCEPT;
 
-    template<class _Yp, class = _EnableIf<
+    template<class _Yp, class = __enable_if_t<
         _And<
             __compatible_with<_Yp, _Tp>
             // In C++03 we get errors when trying to do SFINAE with the
@@ -1093,7 +1093,7 @@
 //
 // std::allocate_shared and std::make_shared
 //
-template<class _Tp, class _Alloc, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
+template<class _Tp, class _Alloc, class ..._Args, class = __enable_if_t<!is_array<_Tp>::value> >
 _LIBCPP_HIDE_FROM_ABI
 shared_ptr<_Tp> allocate_shared(const _Alloc& __a, _Args&& ...__args)
 {
@@ -1105,7 +1105,7 @@
     return shared_ptr<_Tp>::__create_with_control_block((*__control_block).__get_elem(), _VSTD::addressof(*__control_block));
 }
 
-template<class _Tp, class ..._Args, class = _EnableIf<!is_array<_Tp>::value> >
+template<class _Tp, class ..._Args, class = __enable_if_t<!is_array<_Tp>::value> >
 _LIBCPP_HIDE_FROM_ABI
 shared_ptr<_Tp> make_shared(_Args&& ...__args)
 {
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -679,7 +679,7 @@
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR bitset() _NOEXCEPT {}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
         bitset(unsigned long long __v) _NOEXCEPT : base(__v) {}
-    template<class _CharT, class = _EnableIf<_IsCharLikeType<_CharT>::value> >
+    template<class _CharT, class = __enable_if_t<_IsCharLikeType<_CharT>::value> >
         explicit bitset(const _CharT* __str,
                         typename basic_string<_CharT>::size_type __n = basic_string<_CharT>::npos,
                         _CharT __zero = _CharT('0'), _CharT __one = _CharT('1'));
diff --git a/libcxx/include/math.h b/libcxx/include/math.h
--- a/libcxx/include/math.h
+++ b/libcxx/include/math.h
@@ -831,7 +831,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -926,7 +926,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1004,7 +1004,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1158,7 +1158,7 @@
 _LIBCPP_CONSTEXPR
 #endif
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1185,7 +1185,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1242,7 +1242,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1277,7 +1277,7 @@
 
 template <class _A1, class _A2, class _A3>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value &&
@@ -1304,7 +1304,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1325,7 +1325,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1346,7 +1346,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1553,7 +1553,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1584,7 +1584,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1605,7 +1605,7 @@
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::_EnableIf
+typename std::__enable_if_t
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
diff --git a/libcxx/include/queue b/libcxx/include/queue
--- a/libcxx/include/queue
+++ b/libcxx/include/queue
@@ -279,28 +279,28 @@
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         explicit queue(const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         queue(const queue& __q, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__q.c, __a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         queue(const container_type& __c, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__c, __a) {}
 #ifndef _LIBCPP_CXX03_LANG
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         queue(container_type&& __c, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(_VSTD::move(__c), __a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         queue(queue&& __q, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(_VSTD::move(__q.c), __a) {}
 
 #endif // _LIBCPP_CXX03_LANG
@@ -424,7 +424,7 @@
 
 template <class _Tp, class _Container>
 inline _LIBCPP_INLINE_VISIBILITY
-_EnableIf<__is_swappable<_Container>::value, void>
+__enable_if_t<__is_swappable<_Container>::value, void>
 swap(queue<_Tp, _Container>& __x, queue<_Tp, _Container>& __y)
     _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
 {
@@ -491,16 +491,16 @@
     _LIBCPP_INLINE_VISIBILITY
     priority_queue(const value_compare& __comp, container_type&& __c);
 #endif
-    template <class _InputIter, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp = value_compare());
-    template <class _InputIter, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp, const container_type& __c);
 #ifndef _LIBCPP_CXX03_LANG
-    template <class _InputIter, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp, container_type&& __c);
@@ -508,55 +508,55 @@
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         explicit priority_queue(const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(const value_compare& __comp, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(const value_compare& __comp, const container_type& __c,
                        const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(const priority_queue& __q, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 #ifndef _LIBCPP_CXX03_LANG
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(const value_compare& __comp, container_type&& __c,
                        const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(priority_queue&& __q, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 #endif // _LIBCPP_CXX03_LANG
 
-    template <class _InputIter, class _Alloc, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class _Alloc, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 
-    template <class _InputIter, class _Alloc, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class _Alloc, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 
-    template <class _InputIter, class _Alloc, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class _Alloc, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp, const container_type& __c, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 
 #ifndef _LIBCPP_CXX03_LANG
-    template <class _InputIter, class _Alloc, class = _EnableIf<__is_cpp17_input_iterator<_InputIter>::value> >
+    template <class _InputIter, class _Alloc, class = __enable_if_t<__is_cpp17_input_iterator<_InputIter>::value> >
         _LIBCPP_INLINE_VISIBILITY
         priority_queue(_InputIter __f, _InputIter __l,
                        const value_compare& __comp, container_type&& __c, const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0);
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0);
 #endif  // _LIBCPP_CXX03_LANG
 
     _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
@@ -710,7 +710,7 @@
 template <class _Alloc>
 inline
 priority_queue<_Tp, _Container, _Compare>::priority_queue(const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__a)
 {
 }
@@ -720,7 +720,7 @@
 inline
 priority_queue<_Tp, _Container, _Compare>::priority_queue(const value_compare& __comp,
                                                           const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__a),
       comp(__comp)
 {
@@ -732,7 +732,7 @@
 priority_queue<_Tp, _Container, _Compare>::priority_queue(const value_compare& __comp,
                                                           const container_type& __c,
                                                           const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__c, __a),
       comp(__comp)
 {
@@ -744,7 +744,7 @@
 inline
 priority_queue<_Tp, _Container, _Compare>::priority_queue(const priority_queue& __q,
                                                           const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__q.c, __a),
       comp(__q.comp)
 {
@@ -758,7 +758,7 @@
 priority_queue<_Tp, _Container, _Compare>::priority_queue(const value_compare& __comp,
                                                           container_type&& __c,
                                                           const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(_VSTD::move(__c), __a),
       comp(__comp)
 {
@@ -770,7 +770,7 @@
 inline
 priority_queue<_Tp, _Container, _Compare>::priority_queue(priority_queue&& __q,
                                                           const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(_VSTD::move(__q.c), __a),
       comp(_VSTD::move(__q.comp))
 {
@@ -783,7 +783,7 @@
 inline
 priority_queue<_Tp, _Container, _Compare>::priority_queue(
         _InputIter __f, _InputIter __l, const _Alloc& __a,
-        _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+        __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__f, __l, __a),
       comp()
 {
@@ -796,7 +796,7 @@
 priority_queue<_Tp, _Container, _Compare>::priority_queue(
         _InputIter __f, _InputIter __l,
         const value_compare& __comp, const _Alloc& __a,
-        _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+        __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__f, __l, __a),
       comp(__comp)
 {
@@ -809,7 +809,7 @@
 priority_queue<_Tp, _Container, _Compare>::priority_queue(
         _InputIter __f, _InputIter __l,
         const value_compare& __comp, const container_type& __c, const _Alloc& __a,
-        _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+        __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(__c, __a),
       comp(__comp)
 {
@@ -824,7 +824,7 @@
 priority_queue<_Tp, _Container, _Compare>::priority_queue(
         _InputIter __f, _InputIter __l, const value_compare& __comp,
         container_type&& __c, const _Alloc& __a,
-        _EnableIf<uses_allocator<container_type, _Alloc>::value>*)
+        __enable_if_t<uses_allocator<container_type, _Alloc>::value>*)
     : c(_VSTD::move(__c), __a),
       comp(__comp)
 {
@@ -888,7 +888,7 @@
 
 template <class _Tp, class _Container, class _Compare>
 inline _LIBCPP_INLINE_VISIBILITY
-_EnableIf<
+__enable_if_t<
     __is_swappable<_Container>::value && __is_swappable<_Compare>::value,
     void
 >
diff --git a/libcxx/include/stack b/libcxx/include/stack
--- a/libcxx/include/stack
+++ b/libcxx/include/stack
@@ -158,28 +158,28 @@
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         explicit stack(const _Alloc& __a,
-                       _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+                       __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         stack(const container_type& __c, const _Alloc& __a,
-              _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+              __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__c, __a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         stack(const stack& __s, const _Alloc& __a,
-              _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+              __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(__s.c, __a) {}
 #ifndef _LIBCPP_CXX03_LANG
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         stack(container_type&& __c, const _Alloc& __a,
-              _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+              __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(_VSTD::move(__c), __a) {}
     template <class _Alloc>
         _LIBCPP_INLINE_VISIBILITY
         stack(stack&& __s, const _Alloc& __a,
-              _EnableIf<uses_allocator<container_type, _Alloc>::value>* = 0)
+              __enable_if_t<uses_allocator<container_type, _Alloc>::value>* = 0)
             : c(_VSTD::move(__s.c), __a) {}
 #endif // _LIBCPP_CXX03_LANG
 
@@ -297,7 +297,7 @@
 
 template <class _Tp, class _Container>
 inline _LIBCPP_INLINE_VISIBILITY
-_EnableIf<__is_swappable<_Container>::value, void>
+__enable_if_t<__is_swappable<_Container>::value, void>
 swap(stack<_Tp, _Container>& __x, stack<_Tp, _Container>& __y)
     _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
 {
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -832,7 +832,7 @@
     basic_string(basic_string&& __str, const allocator_type& __a);
 #endif // _LIBCPP_CXX03_LANG
 
-    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
+    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
     _LIBCPP_INLINE_VISIBILITY
     basic_string(const _CharT* __s) : __r_(__default_init_tag(), __default_init_tag()) {
       _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
@@ -842,7 +842,7 @@
 #   endif
     }
 
-    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
+    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
         _LIBCPP_INLINE_VISIBILITY
         basic_string(const _CharT* __s, const _Allocator& __a);
 
@@ -857,7 +857,7 @@
     _LIBCPP_INLINE_VISIBILITY
     basic_string(size_type __n, _CharT __c);
 
-    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
+    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
         _LIBCPP_INLINE_VISIBILITY
         basic_string(size_type __n, _CharT __c, const _Allocator& __a);
 
@@ -867,24 +867,24 @@
     basic_string(const basic_string& __str, size_type __pos,
                  const _Allocator& __a = _Allocator());
 
-    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
+    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
         _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
         basic_string(const _Tp& __t, size_type __pos, size_type __n,
                      const allocator_type& __a = allocator_type());
 
-    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
+    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                                           !__is_same_uncvref<_Tp, basic_string>::value> >
         _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
         explicit basic_string(const _Tp& __t);
 
-    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
+    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
         _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
         explicit basic_string(const _Tp& __t, const allocator_type& __a);
 
-    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
+    template<class _InputIterator, class = __enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value> >
         _LIBCPP_INLINE_VISIBILITY
         basic_string(_InputIterator __first, _InputIterator __last);
-    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
+    template<class _InputIterator, class = __enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value> >
         _LIBCPP_INLINE_VISIBILITY
         basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
 #ifndef _LIBCPP_CXX03_LANG
@@ -901,7 +901,7 @@
 
     basic_string& operator=(const basic_string& __str);
 
-    template <class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
+    template <class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
     basic_string& operator=(const _Tp& __t)
         {__self_view __sv = __t; return assign(__sv);}
 
@@ -1004,7 +1004,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
             && !__is_same_uncvref<_Tp, basic_string >::value,
@@ -1022,7 +1022,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf<
+    __enable_if_t<
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
             && !__is_same_uncvref<_Tp, basic_string>::value,
             basic_string&
@@ -1032,7 +1032,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
             && !__is_same_uncvref<_Tp, basic_string>::value,
@@ -1048,7 +1048,7 @@
 
     template<class _InputIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_exactly_cpp17_input_iterator<_InputIterator>::value,
             basic_string&
@@ -1061,7 +1061,7 @@
     }
     template<class _ForwardIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_cpp17_forward_iterator<_ForwardIterator>::value,
             basic_string&
@@ -1084,7 +1084,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             basic_string&
@@ -1101,7 +1101,7 @@
     basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
             && !__is_same_uncvref<_Tp, basic_string>::value,
@@ -1113,7 +1113,7 @@
     basic_string& assign(size_type __n, value_type __c);
     template<class _InputIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_exactly_cpp17_input_iterator<_InputIterator>::value,
             basic_string&
@@ -1121,7 +1121,7 @@
         assign(_InputIterator __first, _InputIterator __last);
     template<class _ForwardIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_cpp17_forward_iterator<_ForwardIterator>::value,
             basic_string&
@@ -1137,7 +1137,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             basic_string&
@@ -1147,7 +1147,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
             basic_string&
@@ -1162,7 +1162,7 @@
     iterator      insert(const_iterator __pos, size_type __n, value_type __c);
     template<class _InputIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_exactly_cpp17_input_iterator<_InputIterator>::value,
             iterator
@@ -1170,7 +1170,7 @@
         insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
     template<class _ForwardIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_cpp17_forward_iterator<_ForwardIterator>::value,
             iterator
@@ -1193,7 +1193,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             basic_string&
@@ -1202,7 +1202,7 @@
     basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
             basic_string&
@@ -1216,7 +1216,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             basic_string&
@@ -1231,7 +1231,7 @@
     basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
     template<class _InputIterator>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __is_cpp17_input_iterator<_InputIterator>::value,
             basic_string&
@@ -1273,7 +1273,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1289,7 +1289,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1305,7 +1305,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1322,7 +1322,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1339,7 +1339,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1356,7 +1356,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             size_type
@@ -1373,7 +1373,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             int
@@ -1382,7 +1382,7 @@
 
     template <class _Tp>
     _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
-    _EnableIf
+    __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
             int
@@ -1395,7 +1395,7 @@
 
     template <class _Tp>
     inline _LIBCPP_INLINE_VISIBILITY
-        _EnableIf
+        __enable_if_t
         <
             __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
             int
@@ -1591,7 +1591,7 @@
 
     template <class _InputIterator>
     inline
-    _EnableIf
+    __enable_if_t
     <
         __is_exactly_cpp17_input_iterator<_InputIterator>::value
     >
@@ -1599,7 +1599,7 @@
 
     template <class _ForwardIterator>
     inline
-    _EnableIf
+    __enable_if_t
     <
         __is_cpp17_forward_iterator<_ForwardIterator>::value
     >
@@ -2136,7 +2136,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _InputIterator>
-_EnableIf
+__enable_if_t
 <
     __is_exactly_cpp17_input_iterator<_InputIterator>::value
 >
@@ -2162,7 +2162,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _ForwardIterator>
-_EnableIf
+__enable_if_t
 <
     __is_cpp17_forward_iterator<_ForwardIterator>::value
 >
@@ -2491,7 +2491,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
-_EnableIf
+__enable_if_t
 <
      __is_exactly_cpp17_input_iterator<_InputIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -2505,7 +2505,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
-_EnableIf
+__enable_if_t
 <
     __is_cpp17_forward_iterator<_ForwardIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -2551,7 +2551,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
     && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
@@ -2684,7 +2684,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
-_EnableIf
+__enable_if_t
 <
     __is_cpp17_forward_iterator<_ForwardIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -2737,7 +2737,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-    _EnableIf
+    __enable_if_t
     <
         __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
         basic_string<_CharT, _Traits, _Allocator>&
@@ -2826,7 +2826,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
-_EnableIf
+__enable_if_t
 <
    __is_exactly_cpp17_input_iterator<_InputIterator>::value,
    typename basic_string<_CharT, _Traits, _Allocator>::iterator
@@ -2844,7 +2844,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _ForwardIterator>
-_EnableIf
+__enable_if_t
 <
     __is_cpp17_forward_iterator<_ForwardIterator>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::iterator
@@ -2914,7 +2914,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -3071,7 +3071,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template<class _InputIterator>
-_EnableIf
+__enable_if_t
 <
     __is_cpp17_input_iterator<_InputIterator>::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -3104,7 +3104,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
     basic_string<_CharT, _Traits, _Allocator>&
@@ -3563,7 +3563,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3621,7 +3621,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3679,7 +3679,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3737,7 +3737,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3795,7 +3795,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3854,7 +3854,7 @@
 
 template<class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     typename basic_string<_CharT, _Traits, _Allocator>::size_type
@@ -3892,7 +3892,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     int
@@ -3946,7 +3946,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
     int
@@ -3971,7 +3971,7 @@
 
 template <class _CharT, class _Traits, class _Allocator>
 template <class _Tp>
-_EnableIf
+__enable_if_t
 <
     __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
     && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -231,7 +231,7 @@
               "Attempted to default construct a reference element in a tuple");}
 
     template <class _Tp,
-              class = _EnableIf<
+              class = __enable_if_t<
                   _And<
                       _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
                       is_constructible<_Hp, _Tp>
@@ -304,7 +304,7 @@
             : _Hp(__a) {}
 
     template <class _Tp,
-              class = _EnableIf<
+              class = __enable_if_t<
                   _And<
                     _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
                     is_constructible<_Hp, _Tp>
@@ -466,7 +466,7 @@
     // [tuple.cnstr]
 
     // tuple() constructors (including allocator_arg_t variants)
-    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible, _EnableIf<
+    template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
         _And<
             _IsImpDefault<_Tp>... // explicit check
         >::value
@@ -477,7 +477,7 @@
     { }
 
     template <template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
-              template<class...> class _IsDefault = is_default_constructible, _EnableIf<
+              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
         _And<
             _IsDefault<_Tp>...,
             _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
@@ -488,7 +488,7 @@
         _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value)
     { }
 
-    template <class _Alloc, template<class...> class _IsImpDefault = __is_implicitly_default_constructible, _EnableIf<
+    template <class _Alloc, template<class...> class _IsImpDefault = __is_implicitly_default_constructible, __enable_if_t<
         _And<
             _IsImpDefault<_Tp>... // explicit check
         >::value
@@ -502,7 +502,7 @@
 
     template <class _Alloc,
               template<class...> class _IsImpDefault = __is_implicitly_default_constructible,
-              template<class...> class _IsDefault = is_default_constructible, _EnableIf<
+              template<class...> class _IsDefault = is_default_constructible, __enable_if_t<
         _And<
             _IsDefault<_Tp>...,
             _Not<_Lazy<_And, _IsImpDefault<_Tp>...> > // explicit check
@@ -516,7 +516,7 @@
                     __tuple_types<_Tp...>()) {}
 
     // tuple(const T&...) constructors (including allocator_arg_t variants)
-    template <template<class...> class _And = _And, _EnableIf<
+    template <template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) >= 1>,
             is_copy_constructible<_Tp>...,
@@ -533,7 +533,7 @@
                 __t...
                ) {}
 
-    template <template<class...> class _And = _And, _EnableIf<
+    template <template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) >= 1>,
             is_copy_constructible<_Tp>...,
@@ -550,7 +550,7 @@
                 __t...
                ) {}
 
-    template <class _Alloc, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) >= 1>,
             is_copy_constructible<_Tp>...,
@@ -567,7 +567,7 @@
                 __t...
                ) {}
 
-    template <class _Alloc, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) >= 1>,
             is_copy_constructible<_Tp>...,
@@ -595,7 +595,7 @@
         is_constructible<_Tp, _Up>...
     > { };
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableUTypesCtor<_Up...>,
@@ -611,7 +611,7 @@
                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
                     _VSTD::forward<_Up>(__u)...) {}
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableUTypesCtor<_Up...>,
@@ -627,7 +627,7 @@
                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
                     _VSTD::forward<_Up>(__u)...) {}
 
-    template <class _Alloc, class ..._Up, _EnableIf<
+    template <class _Alloc, class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableUTypesCtor<_Up...>,
@@ -643,7 +643,7 @@
                     typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),
                     _VSTD::forward<_Up>(__u)...) {}
 
-    template <class _Alloc, class ..._Up, _EnableIf<
+    template <class _Alloc, class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableUTypesCtor<_Up...>,
@@ -663,14 +663,14 @@
     tuple(const tuple&) = default;
     tuple(tuple&&) = default;
 
-    template <class _Alloc, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
         _And<is_copy_constructible<_Tp>...>::value
     , int> = 0>
     tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)
         : __base_(allocator_arg_t(), __alloc, __t)
     { }
 
-    template <class _Alloc, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, template<class...> class _And = _And, __enable_if_t<
         _And<is_move_constructible<_Tp>...>::value
     , int> = 0>
     tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)
@@ -693,7 +693,7 @@
         is_constructible<_Tp, const _Up&>...
     > { };
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableCopyFromOtherTuple<_Up...>,
@@ -706,7 +706,7 @@
         : __base_(__t)
     { }
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableCopyFromOtherTuple<_Up...>,
@@ -719,7 +719,7 @@
         : __base_(__t)
     { }
 
-    template <class ..._Up, class _Alloc, _EnableIf<
+    template <class ..._Up, class _Alloc, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableCopyFromOtherTuple<_Up...>,
@@ -731,7 +731,7 @@
         : __base_(allocator_arg_t(), __a, __t)
     { }
 
-    template <class ..._Up, class _Alloc, _EnableIf<
+    template <class ..._Up, class _Alloc, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableCopyFromOtherTuple<_Up...>,
@@ -759,7 +759,7 @@
         is_constructible<_Tp, _Up>...
     > { };
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableMoveFromOtherTuple<_Up...>,
@@ -772,7 +772,7 @@
         : __base_(_VSTD::move(__t))
     { }
 
-    template <class ..._Up, _EnableIf<
+    template <class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableMoveFromOtherTuple<_Up...>,
@@ -785,7 +785,7 @@
         : __base_(_VSTD::move(__t))
     { }
 
-    template <class _Alloc, class ..._Up, _EnableIf<
+    template <class _Alloc, class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableMoveFromOtherTuple<_Up...>,
@@ -797,7 +797,7 @@
         : __base_(allocator_arg_t(), __a, _VSTD::move(__t))
     { }
 
-    template <class _Alloc, class ..._Up, _EnableIf<
+    template <class _Alloc, class ..._Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>,
             _EnableMoveFromOtherTuple<_Up...>,
@@ -826,7 +826,7 @@
         _Not<is_convertible<const _Up2&, _SecondType<_DependentTp...> > >
     > { };
 
-    template <class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableImplicitCopyFromPair<_Up1, _Up2, _Tp...>
@@ -841,7 +841,7 @@
         : __base_(__p)
     { }
 
-    template <class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableExplicitCopyFromPair<_Up1, _Up2, _Tp...>
@@ -856,7 +856,7 @@
         : __base_(__p)
     { }
 
-    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableImplicitCopyFromPair<_Up1, _Up2, _Tp...>
@@ -867,7 +867,7 @@
         : __base_(allocator_arg_t(), __a, __p)
     { }
 
-    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableExplicitCopyFromPair<_Up1, _Up2, _Tp...>
@@ -895,7 +895,7 @@
         _Not<is_convertible<_Up2, _SecondType<_DependentTp...> > >
     > { };
 
-    template <class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableImplicitMoveFromPair<_Up1, _Up2, _Tp...>
@@ -910,7 +910,7 @@
         : __base_(_VSTD::move(__p))
     { }
 
-    template <class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableExplicitMoveFromPair<_Up1, _Up2, _Tp...>
@@ -925,7 +925,7 @@
         : __base_(_VSTD::move(__p))
     { }
 
-    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableImplicitMoveFromPair<_Up1, _Up2, _Tp...>
@@ -936,7 +936,7 @@
         : __base_(allocator_arg_t(), __a, _VSTD::move(__p))
     { }
 
-    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, _EnableIf<
+    template <class _Alloc, class _Up1, class _Up2, template<class...> class _And = _And, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == 2>,
             _EnableExplicitMoveFromPair<_Up1, _Up2, _Tp...>
@@ -967,7 +967,7 @@
         return *this;
     }
 
-    template<class... _Up, _EnableIf<
+    template<class... _Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
             is_assignable<_Tp&, _Up const&>...
@@ -982,7 +982,7 @@
         return *this;
     }
 
-    template<class... _Up, _EnableIf<
+    template<class... _Up, __enable_if_t<
         _And<
             _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>,
             is_assignable<_Tp&, _Up>...
@@ -998,7 +998,7 @@
         return *this;
     }
 
-    template<class _Up1, class _Up2, class _Dep = true_type, _EnableIf<
+    template<class _Up1, class _Up2, class _Dep = true_type, __enable_if_t<
         _And<_Dep,
             _BoolConstant<sizeof...(_Tp) == 2>,
             is_assignable<_FirstType<_Tp..., _Dep>&, _Up1 const&>,
@@ -1017,7 +1017,7 @@
         return *this;
     }
 
-    template<class _Up1, class _Up2, class _Dep = true_type, _EnableIf<
+    template<class _Up1, class _Up2, class _Dep = true_type, __enable_if_t<
         _And<_Dep,
             _BoolConstant<sizeof...(_Tp) == 2>,
             is_assignable<_FirstType<_Tp..., _Dep>&, _Up1>,
@@ -1037,7 +1037,7 @@
     }
 
     // EXTENSION
-    template<class _Up, size_t _Np, class = _EnableIf<
+    template<class _Up, size_t _Np, class = __enable_if_t<
         _And<
             _BoolConstant<_Np == sizeof...(_Tp)>,
             is_assignable<_Tp&, _Up const&>...
@@ -1053,7 +1053,7 @@
     }
 
     // EXTENSION
-    template<class _Up, size_t _Np, class = void, class = _EnableIf<
+    template<class _Up, size_t _Np, class = void, class = __enable_if_t<
         _And<
             _BoolConstant<_Np == sizeof...(_Tp)>,
             is_assignable<_Tp&, _Up>...
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -458,7 +458,7 @@
 template <bool, class _Tp = void> struct _LIBCPP_TEMPLATE_VIS enable_if {};
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS enable_if<true, _Tp> {typedef _Tp type;};
 
-template <bool _Bp, class _Tp = void> using _EnableIf _LIBCPP_NODEBUG = typename enable_if<_Bp, _Tp>::type;
+template <bool _Bp, class _Tp = void> using __enable_if_t _LIBCPP_NODEBUG = typename enable_if<_Bp, _Tp>::type;
 
 #if _LIBCPP_STD_VER > 11
 template <bool _Bp, class _Tp = void> using enable_if_t = typename enable_if<_Bp, _Tp>::type;
@@ -507,7 +507,7 @@
 
 template <class ...> using __expand_to_true = true_type;
 template <class ..._Pred>
-__expand_to_true<_EnableIf<_Pred::value>...> __and_helper(int);
+__expand_to_true<__enable_if_t<_Pred::value>...> __and_helper(int);
 template <class ...>
 false_type __and_helper(...);
 template <class ..._Pred>
@@ -593,7 +593,7 @@
 
 
 template <class _Tp>
-using __test_for_primary_template = _EnableIf<
+using __test_for_primary_template = __enable_if_t<
     _IsSame<_Tp, typename _Tp::__primary_template>::value
   >;
 template <class _Tp>