Index: include/type_traits
===================================================================
--- include/type_traits
+++ include/type_traits
@@ -1549,6 +1549,48 @@
     = is_convertible<_From, _To>::value;
 #endif
 
+// is_nothrow_convertible
+
+#if _LIBCPP_STD_VER > 17
+
+template <class _Fm, class _To, bool =
+    __or_<
+        is_void<_Fm>, is_function<_To>, is_array<_To>
+    >::value
+>
+struct __is_nothrow_convertable_helper
+{
+    using type = is_void<_To>;
+};
+
+template <typename _Fm, typename _To>
+struct __is_nothrow_convertable_helper<_Fm, _To, false>
+{
+private:
+    template <typename _Tp>
+    static void __test_noexcept(_Tp) noexcept;
+    
+    template<typename __Fm, typename __To>
+    static bool_constant<noexcept(__test_noexcept<__To>(declval<__Fm>()))>
+    __test(int);
+    
+    template<typename, typename>
+    static false_type
+    __test(...);
+    
+public:
+    using type = decltype(__test<_Fm, _To>(0));
+};
+
+template <typename _Fm, typename _To>
+struct is_nothrow_convertible : __is_nothrow_convertable_helper<_Fm, _To>::type
+{ };
+
+template <typename _Fm, typename _To>
+inline constexpr bool is_nothrow_convertible_v = is_nothrow_convertible<_Fm, _To>::value;
+
+#endif // _LIBCPP_STD_VER > 17
+
 // is_empty
 
 #if __has_feature(is_empty) || (_GNUC_VER >= 407)
Index: test/libcxx/type_traits/is_nothrow_convertible.pass.cpp
===================================================================
--- /dev/null
+++ test/libcxx/type_traits/is_nothrow_convertible.pass.cpp
@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+
+// <type_traits>
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+struct A {};
+struct B {
+public:
+    operator A() { return a; } A a;
+};
+
+class C { };
+class D {
+public:
+    operator C() noexcept { return c; } C c;
+};
+
+int main(int, char**) {
+    assert((std::is_nothrow_convertible<int, double>::value));
+    assert(!(std::is_nothrow_convertible<int, char*>::value));
+    
+    assert(!(std::is_nothrow_convertible<A, B>::value));
+    assert((std::is_nothrow_convertible<D, C>::value));
+    
+    assert((std::is_nothrow_convertible_v<int, double>));
+    assert(!(std::is_nothrow_convertible_v<int, char*>));
+    
+    assert(!(std::is_nothrow_convertible_v<A, B>));
+    assert((std::is_nothrow_convertible_v<D, C>));
+    
+    return 0;
+}