diff --git a/libcxx/include/__tuple b/libcxx/include/__tuple
index 8f2e72d6d1c4..196f3c2b5aa5 100644
--- a/libcxx/include/__tuple
+++ b/libcxx/include/__tuple
@@ -387,7 +387,7 @@ template <bool ..._Preds>
 struct __all_dummy;
 
 template <bool ..._Pred>
-using __all = is_same<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)...>>;
+using __all = _IsSame<__all_dummy<_Pred...>, __all_dummy<((void)_Pred, true)...>>;
 
 struct __tuple_sfinae_base {
   template <template <class, class...> class _Trait,
diff --git a/libcxx/include/cmath b/libcxx/include/cmath
index 0f7018f34e3e..f5864be5e11a 100644
--- a/libcxx/include/cmath
+++ b/libcxx/include/cmath
@@ -529,7 +529,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double hypot( long double x, long double y
 
 template <class _A1, class _A2, class _A3>
 inline _LIBCPP_INLINE_VISIBILITY
-typename __lazy_enable_if
+typename _EnableIf
 <
     is_arithmetic<_A1>::value &&
     is_arithmetic<_A2>::value &&
diff --git a/libcxx/include/functional b/libcxx/include/functional
index c0a89f7b0b99..bcd74a9ee597 100644
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -2246,8 +2246,8 @@ class _LIBCPP_TEMPLATE_VIS function<_Rp(_ArgTypes...)>
 
     __func __f_;
 
-    template <class _Fp, bool = __lazy_and<
-        integral_constant<bool, !is_same<__uncvref_t<_Fp>, function>::value>,
+    template <class _Fp, bool = _And<
+        _IsNotSame<__uncvref_t<_Fp>, function>,
         __invokable<_Fp&, _ArgTypes...>
     >::value>
     struct __callable;
@@ -2556,7 +2556,7 @@ __mu_expand(_Ti& __ti, tuple<_Uj...>& __uj, __tuple_indices<_Indx...>)
 
 template <class _Ti, class ..._Uj>
 inline _LIBCPP_INLINE_VISIBILITY
-typename __lazy_enable_if
+typename _EnableIf
 <
     is_bind_expression<_Ti>::value,
     __invoke_of<_Ti&, _Uj...>
diff --git a/libcxx/include/math.h b/libcxx/include/math.h
index 9558321c5206..194df2077bb1 100644
--- a/libcxx/include/math.h
+++ b/libcxx/include/math.h
@@ -857,7 +857,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double atan2(long double __lcpp_y, long do
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -866,8 +866,8 @@ typename std::__lazy_enable_if
 atan2(_A1 __lcpp_y, _A2 __lcpp_x) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::atan2((__result_type)__lcpp_y, (__result_type)__lcpp_x);
 }
 
@@ -952,7 +952,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmod(long double __lcpp_x, long dou
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -961,8 +961,8 @@ typename std::__lazy_enable_if
 fmod(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::fmod((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1030,7 +1030,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double pow(long double __lcpp_x, long doub
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1039,8 +1039,8 @@ typename std::__lazy_enable_if
 pow(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::pow((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1157,7 +1157,7 @@ copysign(long double __lcpp_x, long double __lcpp_y) _NOEXCEPT {
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1166,8 +1166,8 @@ typename std::__lazy_enable_if
 copysign(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::copysign((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1218,7 +1218,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double fdim(long double __lcpp_x, long dou
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1227,8 +1227,8 @@ typename std::__lazy_enable_if
 fdim(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::fdim((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1239,7 +1239,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double fma(long double __lcpp_x, long doub
 
 template <class _A1, class _A2, class _A3>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value &&
@@ -1249,9 +1249,9 @@ typename std::__lazy_enable_if
 fma(_A1 __lcpp_x, _A2 __lcpp_y, _A3 __lcpp_z) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2, _A3>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value &&
-                     std::is_same<_A3, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value &&
+                     std::_IsSame<_A3, __result_type>::value)), "");
     return ::fma((__result_type)__lcpp_x, (__result_type)__lcpp_y, (__result_type)__lcpp_z);
 }
 
@@ -1262,7 +1262,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmax(long double __lcpp_x, long dou
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1271,8 +1271,8 @@ typename std::__lazy_enable_if
 fmax(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::fmax((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1283,7 +1283,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmin(long double __lcpp_x, long dou
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1292,8 +1292,8 @@ typename std::__lazy_enable_if
 fmin(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::fmin((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1304,7 +1304,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double hypot(long double __lcpp_x, long do
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1313,8 +1313,8 @@ typename std::__lazy_enable_if
 hypot(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::hypot((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1427,7 +1427,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double nextafter(long double __lcpp_x, lon
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1436,8 +1436,8 @@ typename std::__lazy_enable_if
 nextafter(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::nextafter((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1458,7 +1458,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double remainder(long double __lcpp_x, lon
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1467,8 +1467,8 @@ typename std::__lazy_enable_if
 remainder(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::remainder((__result_type)__lcpp_x, (__result_type)__lcpp_y);
 }
 
@@ -1479,7 +1479,7 @@ inline _LIBCPP_INLINE_VISIBILITY long double remquo(long double __lcpp_x, long d
 
 template <class _A1, class _A2>
 inline _LIBCPP_INLINE_VISIBILITY
-typename std::__lazy_enable_if
+typename std::_EnableIf
 <
     std::is_arithmetic<_A1>::value &&
     std::is_arithmetic<_A2>::value,
@@ -1488,8 +1488,8 @@ typename std::__lazy_enable_if
 remquo(_A1 __lcpp_x, _A2 __lcpp_y, int* __lcpp_z) _NOEXCEPT
 {
     typedef typename std::__promote<_A1, _A2>::type __result_type;
-    static_assert((!(std::is_same<_A1, __result_type>::value &&
-                     std::is_same<_A2, __result_type>::value)), "");
+    static_assert((!(std::_IsSame<_A1, __result_type>::value &&
+                     std::_IsSame<_A2, __result_type>::value)), "");
     return ::remquo((__result_type)__lcpp_x, (__result_type)__lcpp_y, __lcpp_z);
 }
 
diff --git a/libcxx/include/optional b/libcxx/include/optional
index 1fc752e6ff14..2fad11ce419e 100644
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -618,16 +618,16 @@ private:
       }
     };
     template <class _Up>
-    using _CheckOptionalArgsCtor = conditional_t<
-        !is_same_v<__uncvref_t<_Up>, in_place_t> &&
-        !is_same_v<__uncvref_t<_Up>, optional>,
+    using _CheckOptionalArgsCtor = _If<
+        _IsNotSame<__uncvref_t<_Up>, in_place_t>::value &&
+        _IsNotSame<__uncvref_t<_Up>, optional>::value,
         _CheckOptionalArgsConstructor,
         __check_tuple_constructor_fail
     >;
     template <class _QualUp>
     struct _CheckOptionalLikeConstructor {
       template <class _Up, class _Opt = optional<_Up>>
-      using __check_constructible_from_opt = __lazy_or<
+      using __check_constructible_from_opt = _Or<
           is_constructible<_Tp, _Opt&>,
           is_constructible<_Tp, _Opt const&>,
           is_constructible<_Tp, _Opt&&>,
@@ -638,7 +638,7 @@ private:
           is_convertible<_Opt const&&, _Tp>
       >;
       template <class _Up, class _Opt = optional<_Up>>
-      using __check_assignable_from_opt = __lazy_or<
+      using __check_assignable_from_opt = _Or<
           is_assignable<_Tp&, _Opt&>,
           is_assignable<_Tp&, _Opt const&>,
           is_assignable<_Tp&, _Opt&&>,
@@ -664,18 +664,18 @@ private:
     };
 
     template <class _Up, class _QualUp>
-    using _CheckOptionalLikeCtor = conditional_t<
-      __lazy_and<
-          __lazy_not<is_same<_Up, _Tp>>,
+    using _CheckOptionalLikeCtor = _If<
+      _And<
+         _IsNotSame<_Up, _Tp>,
           is_constructible<_Tp, _QualUp>
       >::value,
       _CheckOptionalLikeConstructor<_QualUp>,
       __check_tuple_constructor_fail
     >;
     template <class _Up, class _QualUp>
-    using _CheckOptionalLikeAssign = conditional_t<
-      __lazy_and<
-          __lazy_not<is_same<_Up, _Tp>>,
+    using _CheckOptionalLikeAssign = _If<
+      _And<
+          _IsNotSame<_Up, _Tp>,
           is_constructible<_Tp, _QualUp>,
           is_assignable<_Tp&, _QualUp>
       >::value,
@@ -689,10 +689,10 @@ public:
     _LIBCPP_INLINE_VISIBILITY constexpr optional(optional&&) = default;
     _LIBCPP_INLINE_VISIBILITY constexpr optional(nullopt_t) noexcept {}
 
-    template <class _InPlaceT, class... _Args, class = enable_if_t<
-        __lazy_and<
-            is_same<_InPlaceT, in_place_t>,
-            is_constructible<value_type, _Args...>
+    template <class _InPlaceT, class... _Args, class = _EnableIf<
+          _And<
+              _IsSame<_InPlaceT, in_place_t>,
+              is_constructible<value_type, _Args...>
             >::value
         >
     >
@@ -700,21 +700,21 @@ public:
     constexpr explicit optional(_InPlaceT, _Args&&... __args)
         : __base(in_place, _VSTD::forward<_Args>(__args)...) {}
 
-    template <class _Up, class... _Args, class = enable_if_t<
+    template <class _Up, class... _Args, class = _EnableIf<
         is_constructible_v<value_type, initializer_list<_Up>&, _Args...>>
     >
     _LIBCPP_INLINE_VISIBILITY
     constexpr explicit optional(in_place_t, initializer_list<_Up> __il, _Args&&... __args)
         : __base(in_place, __il, _VSTD::forward<_Args>(__args)...) {}
 
-    template <class _Up = value_type, enable_if_t<
+    template <class _Up = value_type, _EnableIf<
         _CheckOptionalArgsCtor<_Up>::template __enable_implicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
     constexpr optional(_Up&& __v)
         : __base(in_place, _VSTD::forward<_Up>(__v)) {}
 
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalArgsCtor<_Up>::template __enable_explicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -722,7 +722,7 @@ public:
         : __base(in_place, _VSTD::forward<_Up>(__v)) {}
 
     // LWG2756: conditionally explicit conversion from const optional<_Up>&
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeCtor<_Up, _Up const&>::template __enable_implicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -730,7 +730,7 @@ public:
     {
         this->__construct_from(__v);
     }
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeCtor<_Up, _Up const&>::template __enable_explicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -740,7 +740,7 @@ public:
     }
 
     // LWG2756: conditionally explicit conversion from optional<_Up>&&
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_implicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -748,7 +748,7 @@ public:
     {
         this->__construct_from(_VSTD::move(__v));
     }
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_explicit<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -769,11 +769,12 @@ public:
 
     // LWG2756
     template <class _Up = value_type,
-              class = enable_if_t
-                      <__lazy_and<
-                          integral_constant<bool,
-                              !is_same_v<__uncvref_t<_Up>, optional> &&
-                              !(is_same_v<_Up, value_type> && is_scalar_v<value_type>)
+              class = _EnableIf<
+                      _And<
+                          _IsNotSame<__uncvref_t<_Up>, optional>,
+                          _Or<
+                              _IsNotSame<_Up, value_type>,
+                              _Not<is_scalar<value_type>>
                           >,
                           is_constructible<value_type, _Up>,
                           is_assignable<value_type&, _Up>
@@ -791,7 +792,7 @@ public:
     }
 
     // LWG2756
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeAssign<_Up, _Up const&>::template __enable_assign<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -803,7 +804,7 @@ public:
     }
 
     // LWG2756
-    template <class _Up, enable_if_t<
+    template <class _Up, _EnableIf<
         _CheckOptionalLikeCtor<_Up, _Up &&>::template __enable_assign<_Up>()
     , int> = 0>
     _LIBCPP_INLINE_VISIBILITY
@@ -815,7 +816,7 @@ public:
     }
 
     template <class... _Args,
-              class = enable_if_t
+              class = _EnableIf
                       <
                           is_constructible_v<value_type, _Args...>
                       >
@@ -830,7 +831,7 @@ public:
     }
 
     template <class _Up, class... _Args,
-              class = enable_if_t
+              class = _EnableIf
                       <
                           is_constructible_v<value_type, initializer_list<_Up>&, _Args...>
                       >
@@ -1026,7 +1027,7 @@ template<class T>
 // Comparisons between optionals
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() ==
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1042,7 +1043,7 @@ operator==(const optional<_Tp>& __x, const optional<_Up>& __y)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() !=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1058,7 +1059,7 @@ operator!=(const optional<_Tp>& __x, const optional<_Up>& __y)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1074,7 +1075,7 @@ operator<(const optional<_Tp>& __x, const optional<_Up>& __y)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1090,7 +1091,7 @@ operator>(const optional<_Tp>& __x, const optional<_Up>& __y)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1106,7 +1107,7 @@ operator<=(const optional<_Tp>& __x, const optional<_Up>& __y)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1220,7 +1221,7 @@ operator>=(nullopt_t, const optional<_Tp>& __x) noexcept
 // Comparisons with T
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() ==
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1232,7 +1233,7 @@ operator==(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() ==
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1244,7 +1245,7 @@ operator==(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() !=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1256,7 +1257,7 @@ operator!=(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() !=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1268,7 +1269,7 @@ operator!=(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1280,7 +1281,7 @@ operator<(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1292,7 +1293,7 @@ operator<(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1304,7 +1305,7 @@ operator<=(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() <=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1316,7 +1317,7 @@ operator<=(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1328,7 +1329,7 @@ operator>(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1340,7 +1341,7 @@ operator>(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1352,7 +1353,7 @@ operator>=(const optional<_Tp>& __x, const _Up& __v)
 
 template <class _Tp, class _Up>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<
+_EnableIf<
     is_convertible_v<decltype(_VSTD::declval<const _Tp&>() >=
         _VSTD::declval<const _Up&>()), bool>,
     bool
@@ -1365,7 +1366,7 @@ operator>=(const _Tp& __v, const optional<_Up>& __x)
 
 template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
-enable_if_t<
+_EnableIf<
     is_move_constructible_v<_Tp> && is_swappable_v<_Tp>,
     void
 >
diff --git a/libcxx/include/tuple b/libcxx/include/tuple
index 4e9b5ebde5ad..c192d100e149 100644
--- a/libcxx/include/tuple
+++ b/libcxx/include/tuple
@@ -209,12 +209,12 @@ public:
               "Attempted to default construct a reference element in a tuple");}
 
     template <class _Tp,
-              class = typename enable_if<
-                  __lazy_and<
-                      __lazy_not<is_same<typename __uncvref<_Tp>::type, __tuple_leaf>>
-                    , is_constructible<_Hp, _Tp>
+              class = _EnableIf<
+                  _And<
+                      _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
+                      is_constructible<_Hp, _Tp>
                     >::value
-                >::type
+                >
             >
         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
@@ -291,12 +291,12 @@ public:
             : _Hp(__a) {}
 
     template <class _Tp,
-              class = typename enable_if<
-                  __lazy_and<
-                        __lazy_not<is_same<typename __uncvref<_Tp>::type, __tuple_leaf>>
-                      , is_constructible<_Hp, _Tp>
-                    >::value
-                >::type
+              class = _EnableIf<
+                  _And<
+                    _IsNotSame<__uncvref_t<_Tp>, __tuple_leaf>,
+                    is_constructible<_Hp, _Tp>
+                  >::value
+                >
             >
         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
         explicit __tuple_leaf(_Tp&& __t) _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))
@@ -345,9 +345,6 @@ template <class ..._Tp>
 _LIBCPP_INLINE_VISIBILITY
 void __swallow(_Tp&&...) _NOEXCEPT {}
 
-template <class ..._Tp>
-struct __lazy_all : __all<_Tp::value...> {};
-
 template <class _Tp>
 struct __all_default_constructible;
 
@@ -567,19 +564,19 @@ class _LIBCPP_TEMPLATE_VIS tuple
         // the UTypes... constructor should be selected instead.
         // See LWG issue #2549.
         template <class _Tuple>
-        using _PreferTupleLikeConstructor = __lazy_or<
+        using _PreferTupleLikeConstructor = _Or<
             // Don't attempt the two checks below if the tuple we are given
             // has the same type as this tuple.
-            is_same<typename __uncvref<_Tuple>::type, tuple>,
-            __lazy_and<
-                __lazy_not<is_constructible<_Tp..., _Tuple>>,
-                __lazy_not<is_convertible<_Tuple, _Tp...>>
+            _IsSame<__uncvref_t<_Tuple>, tuple>,
+            _Lazy<_And,
+                _Not<is_constructible<_Tp..., _Tuple>>,
+                _Not<is_convertible<_Tuple, _Tp...>>
             >
         >;
 
         template <class _Tuple>
         static constexpr bool __enable_implicit() {
-            return __lazy_and<
+            return _And<
                 __tuple_convertible<_Tuple, tuple>,
                 _PreferTupleLikeConstructor<_Tuple>
             >::value;
@@ -587,10 +584,10 @@ class _LIBCPP_TEMPLATE_VIS tuple
 
         template <class _Tuple>
         static constexpr bool __enable_explicit() {
-            return __lazy_and<
+            return _And<
                 __tuple_constructible<_Tuple, tuple>,
                 _PreferTupleLikeConstructor<_Tuple>,
-                __lazy_not<__tuple_convertible<_Tuple, tuple>>
+                _Not<__tuple_convertible<_Tuple, tuple>>
             >::value;
         }
     };
@@ -615,12 +612,13 @@ public:
     tuple(tuple const&) = default;
     tuple(tuple&&) = default;
 
-    template <class _AllocArgT, class _Alloc, bool _Dummy = true, class = typename enable_if<
-        __lazy_and<
-            is_same<allocator_arg_t, _AllocArgT>,
-            __lazy_all<__dependent_type<is_default_constructible<_Tp>, _Dummy>...>
+    template <class _AllocArgT, class _Alloc, bool _Dummy = true, class = _EnableIf<
+        _And<
+            _IsSame<allocator_arg_t, _AllocArgT>,
+           __dependent_type<is_default_constructible<_Tp>, _Dummy>...
        >::value
-    >::type>
+      >
+    >
     _LIBCPP_INLINE_VISIBILITY
     tuple(_AllocArgT, _Alloc const& __a)
       : __base_(allocator_arg_t(), __a,
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index def01d459cbf..cdb252cbac6b 100644
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -473,9 +473,9 @@ struct _MetaBase<true> {
   template <class _Tp = void>
   using _EnableIfImpl _LIBCPP_NODEBUG_TYPE = _Tp;
   template <class _Result, class _First, class ..._Rest>
-  using _OrImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::type::value != true && sizeof...(_Rest) != 0>::template _OrImpl<_First, _Rest...>;
+  using _OrImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value != true && sizeof...(_Rest) != 0>::template _OrImpl<_First, _Rest...>;
   template <class _Result, class _First, class ..._Rest>
-  using _AndImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::type::value == true && sizeof...(_Rest) != 0>::template _AndImpl<_First, _Rest...>;
+  using _AndImpl _LIBCPP_NODEBUG_TYPE = typename _MetaBase<_First::value == true && sizeof...(_Rest) != 0>::template _AndImpl<_First, _Rest...>;
 };
 
 template <>
@@ -498,12 +498,15 @@ using _Or _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::te
 template <class ..._Rest>
 using _And _LIBCPP_NODEBUG_TYPE = typename _MetaBase< sizeof...(_Rest) != 0 >::template _AndImpl<true_type, _Rest...>;
 template <class _Pred>
-struct _Not : _BoolConstant<!_Pred::type::value> {};
+struct _Not : _BoolConstant<!_Pred::value> {};
 template <class ..._Args>
 using _FirstType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 1)>::template _FirstImpl<_Args...>;
 template <class ..._Args>
 using _SecondType _LIBCPP_NODEBUG_TYPE = typename _MetaBase<(sizeof...(_Args) >= 2)>::template _SecondImpl<_Args...>;
 
+template <template <class...> class _Func, class ..._Args>
+struct _Lazy : _Func<_Args...> {};
+
 // Member detector base
 
 template <template <class...> class _Templ, class ..._Args>
@@ -532,9 +535,6 @@ template <class _If, class _Then>
 template <bool _Bp, class _If, class _Then> using conditional_t = typename conditional<_Bp, _If, _Then>::type;
 #endif
 
-template <bool, class _Tp> struct _LIBCPP_TEMPLATE_VIS __lazy_enable_if {};
-template <class _Tp> struct _LIBCPP_TEMPLATE_VIS __lazy_enable_if<true, _Tp> {typedef typename _Tp::type type;};
-
 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;};
 
@@ -562,6 +562,14 @@ using _IsSame = _BoolConstant<
 #endif
 >;
 
+template <class _Tp, class _Up>
+using _IsNotSame = _BoolConstant<
+#ifdef __clang__
+    !__is_same(_Tp, _Up)
+#else
+    !_VSTD::is_same<_Tp, _Up>::value
+#endif
+>;
 // addressof
 #ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
 
@@ -635,83 +643,6 @@ struct __two {char __lx[2];};
 
 // helper class:
 
-#if !defined(_LIBCPP_CXX03_LANG)
-
-// __lazy_and
-
-template <bool _Last, class ..._Preds>
-struct __lazy_and_impl;
-
-template <class ..._Preds>
-struct __lazy_and_impl<false, _Preds...> : false_type {};
-
-template <>
-struct __lazy_and_impl<true> : true_type {};
-
-template <class _Pred>
-struct __lazy_and_impl<true, _Pred> : integral_constant<bool, _Pred::type::value> {};
-
-template <class _Hp, class ..._Tp>
-struct __lazy_and_impl<true, _Hp, _Tp...> : __lazy_and_impl<_Hp::type::value, _Tp...> {};
-
-template <class _P1, class ..._Pr>
-struct __lazy_and : __lazy_and_impl<_P1::type::value, _Pr...> {};
-
-// __lazy_or
-
-template <bool _List, class ..._Preds>
-struct __lazy_or_impl;
-
-template <class ..._Preds>
-struct __lazy_or_impl<true, _Preds...> : true_type {};
-
-template <>
-struct __lazy_or_impl<false> : false_type {};
-
-template <class _Hp, class ..._Tp>
-struct __lazy_or_impl<false, _Hp, _Tp...>
-        : __lazy_or_impl<_Hp::type::value, _Tp...> {};
-
-template <class _P1, class ..._Pr>
-struct __lazy_or : __lazy_or_impl<_P1::type::value, _Pr...> {};
-
-// __lazy_not
-
-template <class _Pred>
-struct __lazy_not : integral_constant<bool, !_Pred::type::value> {};
-
-// __and_
-template<class...> struct __and_;
-template<> struct __and_<> : true_type {};
-
-template<class _B0> struct __and_<_B0> : _B0 {};
-
-template<class _B0, class _B1>
-struct __and_<_B0, _B1> : conditional<_B0::value, _B1, _B0>::type {};
-
-template<class _B0, class _B1, class _B2, class... _Bn>
-struct __and_<_B0, _B1, _B2, _Bn...>
-        : conditional<_B0::value, __and_<_B1, _B2, _Bn...>, _B0>::type {};
-
-// __or_
-template<class...> struct __or_;
-template<> struct __or_<> : false_type {};
-
-template<class _B0> struct __or_<_B0> : _B0 {};
-
-template<class _B0, class _B1>
-struct __or_<_B0, _B1> : conditional<_B0::value, _B0, _B1>::type {};
-
-template<class _B0, class _B1, class _B2, class... _Bn>
-struct __or_<_B0, _B1, _B2, _Bn...>
-        : conditional<_B0::value, _B0, __or_<_B1, _B2, _Bn...> >::type {};
-
-// __not_
-template<class _Tp>
-struct __not_ : conditional<_Tp::value, false_type, true_type>::type {};
-
-#endif // !defined(_LIBCPP_CXX03_LANG)
-
 // is_const
 
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_const            : public false_type {};
@@ -1144,7 +1075,7 @@ struct __is_referenceable_impl {
 
 template <class _Tp>
 struct __is_referenceable : integral_constant<bool,
-    !is_same<decltype(__is_referenceable_impl::__test<_Tp>(0)), __two>::value> {};
+    _IsNotSame<decltype(__is_referenceable_impl::__test<_Tp>(0)), __two>::value> {};
 
 
 // add_const
@@ -1249,7 +1180,7 @@ using __uncvref_t _LIBCPP_NODEBUG_TYPE = typename __uncvref<_Tp>::type;
 // __is_same_uncvref
 
 template <class _Tp, class _Up>
-struct __is_same_uncvref : is_same<typename __uncvref<_Tp>::type,
+struct __is_same_uncvref : _IsSame<typename __uncvref<_Tp>::type,
                                    typename __uncvref<_Up>::type> {};
 
 #if _LIBCPP_STD_VER > 17
@@ -1282,7 +1213,7 @@ template <class _Tp> using remove_pointer_t = typename remove_pointer<_Tp>::type
 
 template <class _Tp,
         bool = __is_referenceable<_Tp>::value ||
-                is_same<typename remove_cv<_Tp>::type, void>::value>
+                _IsSame<typename remove_cv<_Tp>::type, void>::value>
 struct __add_pointer_impl
     {typedef _LIBCPP_NODEBUG_TYPE typename remove_reference<_Tp>::type* type;};
 template <class _Tp> struct __add_pointer_impl<_Tp, false>
@@ -1611,9 +1542,9 @@ struct __is_nothrow_convertible_helper: decltype(__is_nothrow_convertible_test<_
 { };
 
 template <typename _Fm, typename _To>
-struct is_nothrow_convertible : __or_<
-    __and_<is_void<_To>, is_void<_Fm>>,
-    __and_<is_convertible<_Fm, _To>, __is_nothrow_convertible_helper<_Fm, _To>>
+struct is_nothrow_convertible : _Or<
+    _And<is_void<_To>, is_void<_Fm>>,
+    _Lazy<_And, is_convertible<_Fm, _To>, __is_nothrow_convertible_helper<_Fm, _To>>
 >::type { };
 
 template <typename _Fm, typename _To>
@@ -1914,7 +1845,7 @@ struct __numeric_type
    static long double __test(long double);
 
    typedef decltype(__test(declval<_Tp>())) type;
-   static const bool value = !is_same<type, void>::value;
+   static const bool value = _IsNotSame<type, void>::value;
 };
 
 template <>
@@ -2199,7 +2130,7 @@ struct _LIBCPP_TEMPLATE_VIS common_type<_Tp>
 template <class _Tp, class _Up>
 struct _LIBCPP_TEMPLATE_VIS common_type<_Tp, _Up>
     : conditional<
-        is_same<_Tp, typename decay<_Tp>::type>::value && is_same<_Up, typename decay<_Up>::type>::value,
+        _IsSame<_Tp, typename decay<_Tp>::type>::value && _IsSame<_Up, typename decay<_Up>::type>::value,
         __common_type2_imp<_Tp, _Up>,
         common_type<typename decay<_Tp>::type, typename decay<_Up>::type>
     >::type
@@ -2770,10 +2701,10 @@ struct __is_invalid_base_to_derived_cast {
   static_assert(is_reference<_To>::value, "Wrong specialization");
   using _RawFrom = __uncvref_t<_From>;
   using _RawTo = __uncvref_t<_To>;
-  static const bool value = __lazy_and<
-        __lazy_not<is_same<_RawFrom, _RawTo>>,
+  static const bool value = _And<
+        _IsNotSame<_RawFrom, _RawTo>,
         is_base_of<_RawFrom, _RawTo>,
-        __lazy_not<__libcpp_is_constructible<_RawTo, _From>>
+        _Not<__libcpp_is_constructible<_RawTo, _From>>
   >::value;
 };
 
@@ -2786,10 +2717,10 @@ template <class _ToRef, class _FromRef>
 struct __is_invalid_lvalue_to_rvalue_cast<_ToRef&&, _FromRef&> {
   using _RawFrom = __uncvref_t<_FromRef>;
   using _RawTo = __uncvref_t<_ToRef>;
-  static const bool value = __lazy_and<
-      __lazy_not<is_function<_RawTo>>,
-      __lazy_or<
-        is_same<_RawFrom, _RawTo>,
+  static const bool value = _And<
+      _Not<is_function<_RawTo>>,
+      _Or<
+        _IsSame<_RawFrom, _RawTo>,
         is_base_of<_RawTo, _RawFrom>>
     >::value;
 };
@@ -3622,7 +3553,7 @@ struct __invokable_r
 
   using type =
   typename conditional<
-      !is_same<_Result, __nat>::value,
+      _IsNotSame<_Result, __nat>::value,
       typename conditional<
           is_void<_Ret>::value,
           true_type,
@@ -3807,8 +3738,8 @@ struct __swappable_with
     typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
     typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;
 
-    static const bool value = !is_same<__swap1, __nat>::value
-                           && !is_same<__swap2, __nat>::value;
+    static const bool value = _IsNotSame<__swap1, __nat>::value
+                           && _IsNotSame<__swap2, __nat>::value;
 };
 
 template <class _Tp, class _Up>
@@ -4002,19 +3933,19 @@ struct __has_operator_addressof
 template <class...> using void_t = void;
 
 template <class... _Args>
-struct conjunction : __and_<_Args...> {};
+struct conjunction : _And<_Args...> {};
 template<class... _Args>
 _LIBCPP_INLINE_VAR constexpr bool conjunction_v
     = conjunction<_Args...>::value;
 
 template <class... _Args>
-struct disjunction : __or_<_Args...> {};
+struct disjunction : _Or<_Args...> {};
 template<class... _Args>
 _LIBCPP_INLINE_VAR constexpr bool disjunction_v
     = disjunction<_Args...>::value;
 
 template <class _Tp>
-struct negation : __not_<_Tp> {};
+struct negation : _Not<_Tp> {};
 template<class _Tp>
 _LIBCPP_INLINE_VAR constexpr bool negation_v
     = negation<_Tp>::value;
@@ -4029,12 +3960,12 @@ struct __extract_key_first_tag {};
 template <class _ValTy, class _Key,
           class _RawValTy = typename __unconstref<_ValTy>::type>
 struct __can_extract_key
-    : conditional<is_same<_RawValTy, _Key>::value, __extract_key_self_tag,
+    : conditional<_IsSame<_RawValTy, _Key>::value, __extract_key_self_tag,
                   __extract_key_fail_tag>::type {};
 
 template <class _Pair, class _Key, class _First, class _Second>
 struct __can_extract_key<_Pair, _Key, pair<_First, _Second>>
-    : conditional<is_same<typename remove_const<_First>::type, _Key>::value,
+    : conditional<_IsSame<typename remove_const<_First>::type, _Key>::value,
                   __extract_key_first_tag, __extract_key_fail_tag>::type {};
 
 // __can_extract_map_key uses true_type/false_type instead of the tags.
@@ -4043,7 +3974,7 @@ struct __can_extract_key<_Pair, _Key, pair<_First, _Second>>
 template <class _ValTy, class _Key, class _ContainerValueTy,
           class _RawValTy = typename __unconstref<_ValTy>::type>
 struct __can_extract_map_key
-    : integral_constant<bool, is_same<_RawValTy, _Key>::value> {};
+    : integral_constant<bool, _IsSame<_RawValTy, _Key>::value> {};
 
 // This specialization returns __extract_key_fail_tag for non-map containers
 // because _Key == _ContainerValueTy
diff --git a/libcxx/test/libcxx/type_traits/lazy_metafunctions.pass.cpp b/libcxx/test/libcxx/type_traits/lazy_metafunctions.pass.cpp
index 59090194009f..cb753971e864 100644
--- a/libcxx/test/libcxx/type_traits/lazy_metafunctions.pass.cpp
+++ b/libcxx/test/libcxx/type_traits/lazy_metafunctions.pass.cpp
@@ -10,7 +10,7 @@
 
 // <type_traits>
 
-// __lazy_enable_if, __lazy_not, __lazy_and and __lazy_or
+// __lazy_enable_if, __lazy_not, _And and _Or
 
 // Test the libc++ lazy meta-programming helpers in <type_traits>
 
@@ -19,8 +19,8 @@
 #include "test_macros.h"
 
 template <class Type>
-struct Identity {
-    typedef Type type;
+struct Identity : Type {
+
 };
 
 typedef std::true_type TrueT;
@@ -32,7 +32,6 @@ typedef Identity<FalseT> LazyFalseT;
 // A type that cannot be instantiated
 template <class T>
 struct CannotInst {
-    typedef T type;
     static_assert(std::is_same<T, T>::value == false, "");
 };
 
@@ -62,32 +61,21 @@ struct HasTypeImp {
 template <class Type>
 struct HasType : HasTypeImp<Type>::type {};
 
-void LazyEnableIfTest() {
-    {
-        typedef std::__lazy_enable_if<true, NextInt<0> > Result;
-        static_assert(HasType<Result>::value, "");
-        static_assert(Result::type::value == 1, "");
-    }
-    {
-        typedef std::__lazy_enable_if<false, CannotInst<int> > Result;
-        static_assert(!HasType<Result>::value, "");
-    }
-}
 
 void LazyNotTest() {
     {
-        typedef std::__lazy_not<LazyTrueT> NotT;
+        typedef std::_Not<LazyTrueT> NotT;
         static_assert(std::is_same<typename NotT::type, FalseT>::value, "");
         static_assert(NotT::value == false, "");
     }
     {
-        typedef std::__lazy_not<LazyFalseT> NotT;
+        typedef std::_Not<LazyFalseT> NotT;
         static_assert(std::is_same<typename NotT::type, TrueT>::value, "");
         static_assert(NotT::value == true, "");
     }
     {
          // Check that CannotInst<int> is not instantiated.
-        typedef std::__lazy_not<CannotInst<int> > NotT;
+        typedef std::_Not<CannotInst<int> > NotT;
 
         static_assert(std::is_same<NotT, NotT>::value, "");
 
@@ -96,42 +84,42 @@ void LazyNotTest() {
 
 void LazyAndTest() {
     { // Test that it acts as the identity function for a single value
-        static_assert(std::__lazy_and<LazyFalseT>::value == false, "");
-        static_assert(std::__lazy_and<LazyTrueT>::value == true, "");
+        static_assert(std::_And<LazyFalseT>::value == false, "");
+        static_assert(std::_And<LazyTrueT>::value == true, "");
     }
     {
-        static_assert(std::__lazy_and<LazyTrueT, LazyTrueT>::value == true, "");
-        static_assert(std::__lazy_and<LazyTrueT, LazyFalseT>::value == false, "");
-        static_assert(std::__lazy_and<LazyFalseT, LazyTrueT>::value == false, "");
-        static_assert(std::__lazy_and<LazyFalseT, LazyFalseT>::value == false, "");
+        static_assert(std::_And<LazyTrueT, LazyTrueT>::value == true, "");
+        static_assert(std::_And<LazyTrueT, LazyFalseT>::value == false, "");
+        static_assert(std::_And<LazyFalseT, LazyTrueT>::value == false, "");
+        static_assert(std::_And<LazyFalseT, LazyFalseT>::value == false, "");
     }
     { // Test short circuiting - CannotInst<T> should never be instantiated.
-        static_assert(std::__lazy_and<LazyFalseT, CannotInst<int>>::value == false, "");
-        static_assert(std::__lazy_and<LazyTrueT, LazyFalseT, CannotInst<int>>::value == false, "");
+        static_assert(std::_And<LazyFalseT, CannotInst<int>>::value == false, "");
+        static_assert(std::_And<LazyTrueT, LazyFalseT, CannotInst<int>>::value == false, "");
     }
 }
 
 
 void LazyOrTest() {
     { // Test that it acts as the identity function for a single value
-        static_assert(std::__lazy_or<LazyFalseT>::value == false, "");
-        static_assert(std::__lazy_or<LazyTrueT>::value == true, "");
+        static_assert(std::_Or<LazyFalseT>::value == false, "");
+        static_assert(std::_Or<LazyTrueT>::value == true, "");
     }
     {
-        static_assert(std::__lazy_or<LazyTrueT, LazyTrueT>::value == true, "");
-        static_assert(std::__lazy_or<LazyTrueT, LazyFalseT>::value == true, "");
-        static_assert(std::__lazy_or<LazyFalseT, LazyTrueT>::value == true, "");
-        static_assert(std::__lazy_or<LazyFalseT, LazyFalseT>::value == false, "");
+        static_assert(std::_Or<LazyTrueT, LazyTrueT>::value == true, "");
+        static_assert(std::_Or<LazyTrueT, LazyFalseT>::value == true, "");
+        static_assert(std::_Or<LazyFalseT, LazyTrueT>::value == true, "");
+        static_assert(std::_Or<LazyFalseT, LazyFalseT>::value == false, "");
     }
     { // Test short circuiting - CannotInst<T> should never be instantiated.
-        static_assert(std::__lazy_or<LazyTrueT, CannotInst<int>>::value == true, "");
-        static_assert(std::__lazy_or<LazyFalseT, LazyTrueT, CannotInst<int>>::value == true, "");
+        static_assert(std::_Or<LazyTrueT, CannotInst<int>>::value == true, "");
+        static_assert(std::_Or<LazyFalseT, LazyTrueT, CannotInst<int>>::value == true, "");
     }
 }
 
 
 int main(int, char**) {
-    LazyEnableIfTest();
+
     LazyNotTest();
     LazyAndTest();
     LazyOrTest();