Index: lib/Frontend/InitPreprocessor.cpp
===================================================================
--- lib/Frontend/InitPreprocessor.cpp
+++ lib/Frontend/InitPreprocessor.cpp
@@ -543,6 +543,7 @@
   // C++20 features.
   if (LangOpts.Char8)
     Builder.defineMacro("__cpp_char8_t", "201811L");
+  Builder.defineMacro("__cpp_impl_destroying_delete", "201806L");
 
   // TS features.
   if (LangOpts.ConceptsTS)
Index: test/Lexer/cxx-features.cpp
===================================================================
--- test/Lexer/cxx-features.cpp
+++ test/Lexer/cxx-features.cpp
@@ -34,6 +34,10 @@
 #error "wrong value for __cpp_char8_t"
 #endif
 
+#if check(impl_destroying_delete, 201806, 201806, 201806, 201806, 201806)
+#error "wrong value for __cpp_impl_destroying_delete"
+#endif
+
 // --- C++17 features ---
 
 #if check(hex_float, 0, 0, 0, 201603, 201603)