diff --git a/llvm/tools/llvm-ml/Opts.td b/llvm/tools/llvm-ml/Opts.td
--- a/llvm/tools/llvm-ml/Opts.td
+++ b/llvm/tools/llvm-ml/Opts.td
@@ -47,6 +47,7 @@
 def assembly_file : MLJoinedOrSeparate<"Ta">, MetaVarName<"<filename>">,
                     HelpText<"Assemble source file with name not ending with "
                              "the .asm extension">;
+def parse_only : MLFlag<"Zs">, HelpText<"Run a syntax-check only">;
 
 def bitness : LLVMJoined<"m">, Values<"32,64">,
               HelpText<"Target platform (x86 or x86-64)">;
@@ -173,4 +174,3 @@
 def structure_packing : UnsupportedJoined<"Zp">, MetaVarName<"<alignment>">,
                         HelpText<"Pack structures with the specified "
                                  "alignment by default">;
-def parse_only : UnsupportedFlag<"Zs">, HelpText<"Run a syntax-check only">;
diff --git a/llvm/tools/llvm-ml/llvm-ml.cpp b/llvm/tools/llvm-ml/llvm-ml.cpp
--- a/llvm/tools/llvm-ml/llvm-ml.cpp
+++ b/llvm/tools/llvm-ml/llvm-ml.cpp
@@ -74,11 +74,11 @@
 
 class MLOptTable : public opt::OptTable {
 public:
-  MLOptTable() : OptTable(InfoTable, true) {}
+  MLOptTable() : OptTable(InfoTable, /*IgnoreCase=*/false) {}
 };
 } // namespace
 
-static Triple GetTriple(StringRef ProgName, opt::InputArgList &Args) {
+static Triple GetTriple(StringRef ProgName, opt::ArgList &Args) {
   // Figure out the target triple.
   StringRef DefaultBitness = "32";
   SmallString<255> Program = ProgName;
@@ -128,7 +128,7 @@
                          SourceMgr &SrcMgr, MCContext &Ctx, MCStreamer &Str,
                          MCAsmInfo &MAI, MCSubtargetInfo &STI,
                          MCInstrInfo &MCII, MCTargetOptions &MCOptions,
-                         const opt::ArgList &InputArgs) {
+                         const opt::ArgList &Args) {
   std::unique_ptr<MCAsmParser> Parser(
       createMCMasmParser(SrcMgr, Ctx, Str, MAI, 0));
   std::unique_ptr<MCTargetAsmParser> TAP(
@@ -140,14 +140,14 @@
     return 1;
   }
 
-  Parser->setShowParsedOperands(InputArgs.hasArg(OPT_show_inst_operands));
+  Parser->setShowParsedOperands(Args.hasArg(OPT_show_inst_operands));
   Parser->setTargetParser(*TAP);
   Parser->getLexer().setLexMasmIntegers(true);
   Parser->getLexer().useMasmDefaultRadix(true);
   Parser->getLexer().setLexMasmHexFloats(true);
   Parser->getLexer().setLexMasmStrings(true);
 
-  auto Defines = InputArgs.getAllArgValues(OPT_define);
+  auto Defines = Args.getAllArgValues(OPT_define);
   for (StringRef Define : Defines) {
     const auto NameValue = Define.split('=');
     StringRef Name = NameValue.first, Value = NameValue.second;
@@ -179,9 +179,14 @@
   opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgIndex, MissingArgCount);
 
+  opt::DerivedArgList Args(InputArgs);
+  for (auto *Arg : InputArgs) {
+    Args.append(Arg);
+  }
+
   std::string InputFilename;
-  for (auto *Arg : InputArgs.filtered(OPT_INPUT)) {
-    std::string ArgString = Arg->getAsString(InputArgs);
+  for (auto *Arg : Args.filtered(OPT_INPUT)) {
+    std::string ArgString = Arg->getAsString(Args);
     if (ArgString == "-" || StringRef(ArgString).endswith(".asm")) {
       if (!InputFilename.empty()) {
         WithColor::warning(errs(), ProgName)
@@ -202,22 +207,22 @@
       exit(1);
     }
   }
-  for (auto *Arg : InputArgs.filtered(OPT_assembly_file)) {
+  for (auto *Arg : Args.filtered(OPT_assembly_file)) {
     if (!InputFilename.empty()) {
       WithColor::warning(errs(), ProgName)
           << "does not support multiple assembly files in one command; "
           << "ignoring '" << InputFilename << "'\n";
     }
-    InputFilename = Arg->getAsString(InputArgs);
+    InputFilename = Arg->getAsString(Args);
   }
 
-  for (auto &Arg : InputArgs.filtered(OPT_unsupported_Group)) {
+  for (auto &Arg : Args.filtered(OPT_unsupported_Group)) {
     WithColor::warning(errs(), ProgName)
         << "ignoring unsupported '" << Arg->getOption().getName()
         << "' option\n";
   }
 
-  if (InputArgs.hasArg(OPT_help)) {
+  if (Args.hasArg(OPT_help)) {
     std::string Usage = llvm::formatv("{0} [ /options ] file", ProgName).str();
     T.PrintHelp(outs(), Usage.c_str(), "LLVM MASM Assembler",
                 /*ShowHidden=*/false);
@@ -229,10 +234,13 @@
     return 0;
   }
 
+  if (Args.hasArg(OPT_parse_only))
+    Args.AddJoinedArg(nullptr, T.getOption(OPT_filetype), "null");
+
   MCTargetOptions MCOptions;
   MCOptions.AssemblyLanguage = "masm";
 
-  Triple TheTriple = GetTriple(ProgName, InputArgs);
+  Triple TheTriple = GetTriple(ProgName, Args);
   std::string Error;
   const Target *TheTarget = TargetRegistry::lookupTarget("", TheTriple, Error);
   if (!TheTarget) {
@@ -241,7 +249,7 @@
   }
   const std::string &TripleName = TheTriple.getTriple();
 
-  bool SafeSEH = InputArgs.hasArg(OPT_safeseh);
+  bool SafeSEH = Args.hasArg(OPT_safeseh);
   if (SafeSEH && !(TheTriple.isArch32Bit() && TheTriple.isX86())) {
     WithColor::warning()
         << "/safeseh applies only to 32-bit X86 platforms; ignoring.\n";
@@ -263,7 +271,7 @@
 
   // Record the location of the include directories so that the lexer can find
   // it later.
-  SrcMgr.setIncludeDirs(InputArgs.getAllArgValues(OPT_include_path));
+  SrcMgr.setIncludeDirs(Args.getAllArgValues(OPT_include_path));
 
   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
   assert(MRI && "Unable to create target register info!");
@@ -272,7 +280,7 @@
       TheTarget->createMCAsmInfo(*MRI, TripleName, MCOptions));
   assert(MAI && "Unable to create target asm info!");
 
-  MAI->setPreserveAsmComments(InputArgs.hasArg(OPT_preserve_comments));
+  MAI->setPreserveAsmComments(Args.hasArg(OPT_preserve_comments));
 
   // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
   // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
@@ -281,7 +289,7 @@
   MOFI.InitMCObjectFileInfo(TheTriple, /*PIC=*/false, Ctx,
                             /*LargeCodeModel=*/true);
 
-  if (InputArgs.hasArg(OPT_save_temp_labels))
+  if (Args.hasArg(OPT_save_temp_labels))
     Ctx.setAllowTemporaryLabels(false);
 
   // Set compilation information.
@@ -290,16 +298,16 @@
     Ctx.setCompilationDir(CWD);
   Ctx.setMainFileName(InputFilename);
 
-  StringRef FileType = InputArgs.getLastArgValue(OPT_filetype, "obj");
+  StringRef FileType = Args.getLastArgValue(OPT_filetype, "obj");
   SmallString<255> DefaultOutputFilename;
-  if (InputArgs.hasArg(OPT_as_lex)) {
+  if (Args.hasArg(OPT_as_lex)) {
     DefaultOutputFilename = "-";
   } else {
     DefaultOutputFilename = InputFilename;
     sys::path::replace_extension(DefaultOutputFilename, FileType);
   }
   const StringRef OutputFilename =
-      InputArgs.getLastArgValue(OPT_output_file, DefaultOutputFilename);
+      Args.getLastArgValue(OPT_output_file, DefaultOutputFilename);
   std::unique_ptr<ToolOutputFile> Out = GetOutputStream(OutputFilename);
   if (!Out)
     return 1;
@@ -317,7 +325,7 @@
 
   MCInstPrinter *IP = nullptr;
   if (FileType == "s") {
-    const bool OutputATTAsm = InputArgs.hasArg(OPT_output_att_asm);
+    const bool OutputATTAsm = Args.hasArg(OPT_output_att_asm);
     const unsigned OutputAsmVariant = OutputATTAsm ? 0U   // ATT dialect
                                                    : 1U;  // Intel dialect
     IP = TheTarget->createMCInstPrinter(TheTriple, OutputAsmVariant, *MAI,
@@ -332,11 +340,11 @@
     }
 
     // Set the display preference for hex vs. decimal immediates.
-    IP->setPrintImmHex(InputArgs.hasArg(OPT_print_imm_hex));
+    IP->setPrintImmHex(Args.hasArg(OPT_print_imm_hex));
 
     // Set up the AsmStreamer.
     std::unique_ptr<MCCodeEmitter> CE;
-    if (InputArgs.hasArg(OPT_show_encoding))
+    if (Args.hasArg(OPT_show_encoding))
       CE.reset(TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx));
 
     std::unique_ptr<MCAsmBackend> MAB(
@@ -345,7 +353,7 @@
     Str.reset(TheTarget->createAsmStreamer(
         Ctx, std::move(FOut), /*asmverbose*/ true,
         /*useDwarfDirectory*/ true, IP, std::move(CE), std::move(MAB),
-        InputArgs.hasArg(OPT_show_inst)));
+        Args.hasArg(OPT_show_inst)));
 
   } else if (FileType == "null") {
     Str.reset(TheTarget->createNullStreamer(Ctx));
@@ -387,12 +395,12 @@
   Str->setUseAssemblerInfoForParsing(true);
 
   int Res = 1;
-  if (InputArgs.hasArg(OPT_as_lex)) {
+  if (Args.hasArg(OPT_as_lex)) {
     // -as-lex; Lex only, and output a stream of tokens
     Res = AsLexInput(SrcMgr, *MAI, Out->os());
   } else {
     Res = AssembleInput(ProgName, TheTarget, SrcMgr, Ctx, *Str, *MAI, *STI,
-                        *MCII, MCOptions, InputArgs);
+                        *MCII, MCOptions, Args);
   }
 
   // Keep output if no errors.