diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2572,11 +2572,18 @@
   }
 
   // Warn -x after last input file has no effect
-  {
+  if (!IsCLMode()) {
     Arg *LastXArg = Args.getLastArgNoClaim(options::OPT_x);
     Arg *LastInputArg = Args.getLastArgNoClaim(options::OPT_INPUT);
-    if (LastXArg && LastInputArg && LastInputArg->getIndex() < LastXArg->getIndex())
+    if (LastXArg && LastInputArg &&
+        LastInputArg->getIndex() < LastXArg->getIndex())
       Diag(clang::diag::warn_drv_unused_x) << LastXArg->getValue();
+  } else {
+    // In CL mode suggest /TC or /TP since -x doesn't make sense if passed via
+    // /clang:.
+    if (auto *A = Args.getLastArg(options::OPT_x))
+      Diag(diag::err_drv_unsupported_opt_with_suggestion)
+          << A->getAsString(Args) << "/TC' or '/TP";
   }
 
   for (Arg *A : Args) {
diff --git a/clang/test/ClangScanDeps/Inputs/modules_cdb_clangcl_by_mod_name.json b/clang/test/ClangScanDeps/Inputs/modules_cdb_clangcl_by_mod_name.json
--- a/clang/test/ClangScanDeps/Inputs/modules_cdb_clangcl_by_mod_name.json
+++ b/clang/test/ClangScanDeps/Inputs/modules_cdb_clangcl_by_mod_name.json
@@ -1,12 +1,12 @@
 [
 {
   "directory": "DIR",
-  "command": "clang-cl /E /IInputs /D INCLUDE_HEADER2 /clang:-MD /clang:-MF /clang:DIR/modules_cdb2_clangcl.d /clang:-fmodules /clang:-fcxx-modules /clang:-fmodules-cache-path=DIR/module-cache_clangcl /clang:-fimplicit-modules /clang:-fimplicit-module-maps /clang:-x /clang:c++ --",
+  "command": "clang-cl /E /IInputs /D INCLUDE_HEADER2 /clang:-MD /clang:-MF /clang:DIR/modules_cdb2_clangcl.d /clang:-fmodules /clang:-fcxx-modules /clang:-fmodules-cache-path=DIR/module-cache_clangcl /clang:-fimplicit-modules /clang:-fimplicit-module-maps /TP --",
   "file": ""
 },
 {
   "directory": "DIR",
-  "command": "clang-cl /E /IInputs /clang:-fmodules /clang:-fcxx-modules /clang:-fmodules-cache-path=DIR/module-cache_clangcl /clang:-fimplicit-modules /clang:-fimplicit-module-maps /clang:-x /clang:c++ --",
+  "command": "clang-cl /E /IInputs /clang:-fmodules /clang:-fcxx-modules /clang:-fmodules-cache-path=DIR/module-cache_clangcl /clang:-fimplicit-modules /clang:-fimplicit-module-maps /TP --",
   "file": ""
 },
 ]
diff --git a/clang/test/Driver/x-args.c b/clang/test/Driver/x-args.c
--- a/clang/test/Driver/x-args.c
+++ b/clang/test/Driver/x-args.c
@@ -5,3 +5,8 @@
 // RUN: %clang -fsyntax-only -xc %s -xc++ -fsyntax-only 2>&1 | FileCheck %s
 // RUN: %clang -fsyntax-only %s -xc %s -xc++ -fsyntax-only 2>&1 | FileCheck %s
 // CHECK: '-x c++' after last input file has no effect
+
+// RUN: not %clang_cl /WX /clang:-xc /clang:-E /clang:-dM %s 2>&1 | FileCheck -check-prefix=CL %s
+// RUN: not %clang_cl /WX /clang:-E /clang:-dM %s /clang:-xc 2>&1 | FileCheck -check-prefix=CL %s
+// CL-NOT: '-x c' after last input file has no effect
+// CL: error: unsupported option '-x c'; did you mean '/TC' or '/TP'?