diff --git a/libcxx/include/__math/exponential_functions.h b/libcxx/include/__math/exponential_functions.h
--- a/libcxx/include/__math/exponential_functions.h
+++ b/libcxx/include/__math/exponential_functions.h
@@ -159,7 +159,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type pow(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::pow((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/fdim.h b/libcxx/include/__math/fdim.h
--- a/libcxx/include/__math/fdim.h
+++ b/libcxx/include/__math/fdim.h
@@ -36,7 +36,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type fdim(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::fdim((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/fma.h b/libcxx/include/__math/fma.h
--- a/libcxx/include/__math/fma.h
+++ b/libcxx/include/__math/fma.h
@@ -41,7 +41,7 @@
           class _A3,
           __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value && is_arithmetic<_A3>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2, _A3>::type fma(_A1 __x, _A2 __y, _A3 __z) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2, _A3>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2, _A3>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value &&
                    _IsSame<_A3, __result_type>::value)),
                 "");
diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h
--- a/libcxx/include/__math/hypot.h
+++ b/libcxx/include/__math/hypot.h
@@ -36,7 +36,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type hypot(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::hypot((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/inverse_trigonometric_functions.h b/libcxx/include/__math/inverse_trigonometric_functions.h
--- a/libcxx/include/__math/inverse_trigonometric_functions.h
+++ b/libcxx/include/__math/inverse_trigonometric_functions.h
@@ -87,7 +87,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type atan2(_A1 __y, _A2 __x) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::atan2((__result_type)__y, (__result_type)__x);
 }
diff --git a/libcxx/include/__math/min_max.h b/libcxx/include/__math/min_max.h
--- a/libcxx/include/__math/min_max.h
+++ b/libcxx/include/__math/min_max.h
@@ -40,7 +40,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type fmax(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::fmax((__result_type)__x, (__result_type)__y);
 }
@@ -62,7 +62,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type fmin(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::fmin((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/modulo.h b/libcxx/include/__math/modulo.h
--- a/libcxx/include/__math/modulo.h
+++ b/libcxx/include/__math/modulo.h
@@ -38,7 +38,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type fmod(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::fmod((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/remainder.h b/libcxx/include/__math/remainder.h
--- a/libcxx/include/__math/remainder.h
+++ b/libcxx/include/__math/remainder.h
@@ -39,7 +39,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type remainder(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::remainder((__result_type)__x, (__result_type)__y);
 }
@@ -61,7 +61,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type remquo(_A1 __x, _A2 __y, int* __z) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::remquo((__result_type)__x, (__result_type)__y, __z);
 }
diff --git a/libcxx/include/__math/rounding_functions.h b/libcxx/include/__math/rounding_functions.h
--- a/libcxx/include/__math/rounding_functions.h
+++ b/libcxx/include/__math/rounding_functions.h
@@ -159,7 +159,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 inline _LIBCPP_HIDE_FROM_ABI __promote<_A1, _A2>::type nextafter(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type __result_type;
+  using __result_type = typename __promote<_A1, _A2>::type;
   static_assert((!(_IsSame<_A1, __result_type>::value && _IsSame<_A2, __result_type>::value)), "");
   return __math::nextafter((__result_type)__x, (__result_type)__y);
 }
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -125,7 +125,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool isgreater(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_isgreater((type)__x, (type)__y);
 }
 
@@ -133,7 +133,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool isgreaterequal(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_isgreaterequal((type)__x, (type)__y);
 }
 
@@ -141,7 +141,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool isless(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_isless((type)__x, (type)__y);
 }
 
@@ -149,7 +149,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool islessequal(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_islessequal((type)__x, (type)__y);
 }
 
@@ -157,7 +157,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool islessgreater(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_islessgreater((type)__x, (type)__y);
 }
 
@@ -165,7 +165,7 @@
 
 template <class _A1, class _A2, __enable_if_t<is_arithmetic<_A1>::value && is_arithmetic<_A2>::value, int> = 0>
 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI bool isunordered(_A1 __x, _A2 __y) _NOEXCEPT {
-  typedef typename __promote<_A1, _A2>::type type;
+  using type = typename __promote<_A1, _A2>::type;
   return __builtin_isunordered((type)__x, (type)__y);
 }