diff --git a/libcxx/include/utility b/libcxx/include/utility
index 958378b8ba3e..00e3cd208ecb 100644
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -930,6 +930,12 @@ template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_t
 template <class _Tp>
 using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>;
 
+template <class _Tp> struct __is_inplace_index_imp : false_type {};
+template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
+
+template <class _Tp>
+using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>;
+
 #endif // _LIBCPP_STD_VER > 14
 
 template <class _Arg, class _Result>
diff --git a/libcxx/test/libcxx/utilities/utility/__is_inplace_index.pass.cpp b/libcxx/test/libcxx/utilities/utility/__is_inplace_index.pass.cpp
new file mode 100644
index 000000000000..bcb2f91ac9d4
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/utility/__is_inplace_index.pass.cpp
@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// template <class _Tp> using __is_inplace_index
+
+#include <utility>
+
+struct S {};
+
+int main() {
+  using I = std::in_place_index_t<0>;
+  static_assert( std::__is_inplace_index<I>::value, "");
+  static_assert( std::__is_inplace_index<const I>::value, "");
+  static_assert( std::__is_inplace_index<const volatile I>::value, "");
+  static_assert( std::__is_inplace_index<I&>::value, "");
+  static_assert( std::__is_inplace_index<const I&>::value, "");
+  static_assert( std::__is_inplace_index<const volatile I&>::value, "");
+  static_assert( std::__is_inplace_index<I&&>::value, "");
+  static_assert( std::__is_inplace_index<const I&&>::value, "");
+  static_assert( std::__is_inplace_index<const volatile I&&>::value, "");
+  static_assert(!std::__is_inplace_index<std::in_place_type_t<int>>::value, "");
+  static_assert(!std::__is_inplace_index<std::in_place_t>::value, "");
+  static_assert(!std::__is_inplace_index<void>::value, "");
+  static_assert(!std::__is_inplace_index<int>::value, "");
+  static_assert(!std::__is_inplace_index<S>::value, "");
+}
diff --git a/libcxx/test/libcxx/utilities/utility/__is_inplace_type.pass.cpp b/libcxx/test/libcxx/utilities/utility/__is_inplace_type.pass.cpp
new file mode 100644
index 000000000000..10a4aa57174f
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/utility/__is_inplace_type.pass.cpp
@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// template <class _Tp> using __is_inplace_type
+
+#include <utility>
+
+struct S {};
+
+int main() {
+  using T = std::in_place_type_t<int>;
+  static_assert( std::__is_inplace_type<T>::value, "");
+  static_assert( std::__is_inplace_type<const T>::value, "");
+  static_assert( std::__is_inplace_type<const volatile T>::value, "");
+  static_assert( std::__is_inplace_type<T&>::value, "");
+  static_assert( std::__is_inplace_type<const T&>::value, "");
+  static_assert( std::__is_inplace_type<const volatile T&>::value, "");
+  static_assert( std::__is_inplace_type<T&&>::value, "");
+  static_assert( std::__is_inplace_type<const T&&>::value, "");
+  static_assert( std::__is_inplace_type<const volatile T&&>::value, "");
+  static_assert(!std::__is_inplace_type<std::in_place_index_t<0>>::value, "");
+  static_assert(!std::__is_inplace_type<std::in_place_t>::value, "");
+  static_assert(!std::__is_inplace_type<void>::value, "");
+  static_assert(!std::__is_inplace_type<int>::value, "");
+  static_assert(!std::__is_inplace_type<S>::value, "");
+}