diff --git a/clang/include/clang/Frontend/CompilerInvocation.h b/clang/include/clang/Frontend/CompilerInvocation.h
--- a/clang/include/clang/Frontend/CompilerInvocation.h
+++ b/clang/include/clang/Frontend/CompilerInvocation.h
@@ -249,7 +249,8 @@
   /// Generate command line options from DiagnosticOptions.
   static void GenerateDiagnosticArgs(const DiagnosticOptions &Opts,
                                      SmallVectorImpl<const char *> &Args,
-                                     StringAllocator SA, bool DefaultDiagColor);
+                                     StringAllocator SA, bool DefaultDiagColor,
+                                     const llvm::Triple &T, InputKind DashX);
 
   /// Parse command line options that map to LangOptions.
   static bool ParseLangArgsImpl(LangOptions &Opts, llvm::opt::ArgList &Args,
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2295,7 +2295,8 @@
 
 void CompilerInvocation::GenerateDiagnosticArgs(
     const DiagnosticOptions &Opts, SmallVectorImpl<const char *> &Args,
-    StringAllocator SA, bool DefaultDiagColor) {
+    StringAllocator SA, bool DefaultDiagColor, const llvm::Triple &T,
+    InputKind DashX) {
   const DiagnosticOptions *DiagnosticOpts = &Opts;
 #define DIAG_OPTION_WITH_MARSHALLING(                                          \
     PREFIX_TYPE, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,        \
@@ -2343,6 +2344,13 @@
     // This option is automatically generated from UndefPrefixes.
     if (Warning == "undef-prefix")
       continue;
+    // This warning was manufactured, don't put it on the command line.
+    if (Warning == "no-stdlibcxx-not-found" && T.isOSDarwin() &&
+        DashX.isPreprocessed())
+      continue;
+    // This warning was manufactured, don't put it on the command line.
+    if (Warning == "spir-compat" && T.isSPIR())
+      continue;
     Args.push_back(SA(StringRef("-W") + Warning));
   }
 
@@ -4831,11 +4839,12 @@
 void CompilerInvocation::generateCC1CommandLine(
     SmallVectorImpl<const char *> &Args, StringAllocator SA) const {
   llvm::Triple T(TargetOpts->Triple);
+  InputKind DashX = FrontendOpts.DashX;
 
   GenerateFileSystemArgs(FileSystemOpts, Args, SA);
   GenerateMigratorArgs(MigratorOpts, Args, SA);
   GenerateAnalyzerArgs(*AnalyzerOpts, Args, SA);
-  GenerateDiagnosticArgs(*DiagnosticOpts, Args, SA, false);
+  GenerateDiagnosticArgs(*DiagnosticOpts, Args, SA, false, T, DashX);
   GenerateFrontendArgs(FrontendOpts, Args, SA, LangOpts->IsHeaderFile);
   GenerateTargetArgs(*TargetOpts, Args, SA);
   GenerateHeaderSearchArgs(*HeaderSearchOpts, Args, SA);