diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -278,6 +278,7 @@
            .Case("gch", TY_PCH)
            .Case("hip", TY_HIP)
            .Case("hpp", TY_CXXHeader)
+           .Case("hxx", TY_CXXHeader)
            .Case("iim", TY_PP_CXXModule)
            .Case("lib", TY_Object)
            .Case("mii", TY_PP_ObjCXX)
diff --git a/clang/lib/Frontend/FrontendOptions.cpp b/clang/lib/Frontend/FrontendOptions.cpp
--- a/clang/lib/Frontend/FrontendOptions.cpp
+++ b/clang/lib/Frontend/FrontendOptions.cpp
@@ -25,7 +25,7 @@
       .Cases("mm", "M", Language::ObjCXX)
       .Case("mii", InputKind(Language::ObjCXX).getPreprocessed())
       .Cases("C", "cc", "cp", Language::CXX)
-      .Cases("cpp", "CPP", "c++", "cxx", "hpp", Language::CXX)
+      .Cases("cpp", "CPP", "c++", "cxx", "hpp", "hxx", Language::CXX)
       .Case("cppm", Language::CXX)
       .Case("iim", InputKind(Language::CXX).getPreprocessed())
       .Case("cl", Language::OpenCL)