diff --git a/llvm/include/llvm/Object/COFFModuleDefinition.h b/llvm/include/llvm/Object/COFFModuleDefinition.h
--- a/llvm/include/llvm/Object/COFFModuleDefinition.h
+++ b/llvm/include/llvm/Object/COFFModuleDefinition.h
@@ -41,7 +41,7 @@
 
 Expected<COFFModuleDefinition>
 parseCOFFModuleDefinition(MemoryBufferRef MB, COFF::MachineTypes Machine,
-                          bool MingwDef = false);
+                          bool MingwDef = false, bool AddUnderscores = true);
 
 } // End namespace object.
 } // End namespace llvm.
diff --git a/llvm/lib/Object/COFFModuleDefinition.cpp b/llvm/lib/Object/COFFModuleDefinition.cpp
--- a/llvm/lib/Object/COFFModuleDefinition.cpp
+++ b/llvm/lib/Object/COFFModuleDefinition.cpp
@@ -138,8 +138,11 @@
 
 class Parser {
 public:
-  explicit Parser(StringRef S, MachineTypes M, bool B)
-      : Lex(S), Machine(M), MingwDef(B) {}
+  explicit Parser(StringRef S, MachineTypes M, bool B, bool AU)
+      : Lex(S), Machine(M), MingwDef(B), AddUnderscores(AU) {
+    if (Machine != IMAGE_FILE_MACHINE_I386)
+      AddUnderscores = false;
+  }
 
   Expected<COFFModuleDefinition> parse() {
     do {
@@ -234,7 +237,7 @@
       unget();
     }
 
-    if (Machine == IMAGE_FILE_MACHINE_I386) {
+    if (AddUnderscores) {
       if (!isDecorated(E.Name, MingwDef))
         E.Name = (std::string("_").append(E.Name));
       if (!E.ExtName.empty() && !isDecorated(E.ExtName, MingwDef))
@@ -279,7 +282,7 @@
       if (Tok.K == EqualEqual) {
         read();
         E.AliasTarget = std::string(Tok.Value);
-        if (Machine == IMAGE_FILE_MACHINE_I386 && !isDecorated(E.AliasTarget, MingwDef))
+        if (AddUnderscores && !isDecorated(E.AliasTarget, MingwDef))
           E.AliasTarget = std::string("_").append(E.AliasTarget);
         continue;
       }
@@ -349,12 +352,14 @@
   MachineTypes Machine;
   COFFModuleDefinition Info;
   bool MingwDef;
+  bool AddUnderscores;
 };
 
 Expected<COFFModuleDefinition> parseCOFFModuleDefinition(MemoryBufferRef MB,
                                                          MachineTypes Machine,
-                                                         bool MingwDef) {
-  return Parser(MB.getBuffer(), Machine, MingwDef).parse();
+                                                         bool MingwDef,
+                                                         bool AddUnderscores) {
+  return Parser(MB.getBuffer(), Machine, MingwDef, AddUnderscores).parse();
 }
 
 } // namespace object
diff --git a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
--- a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
+++ b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
@@ -165,8 +165,9 @@
     return 1;
   }
 
-  Expected<COFFModuleDefinition> Def =
-      parseCOFFModuleDefinition(*MB, Machine, /*MingwDef=*/true);
+  bool AddUnderscores = !Args.hasArg(OPT_no_leading_underscore);
+  Expected<COFFModuleDefinition> Def = parseCOFFModuleDefinition(
+      *MB, Machine, /*MingwDef=*/true, AddUnderscores);
 
   if (!Def) {
     llvm::errs() << "error parsing definition\n"
diff --git a/llvm/lib/ToolDrivers/llvm-dlltool/Options.td b/llvm/lib/ToolDrivers/llvm-dlltool/Options.td
--- a/llvm/lib/ToolDrivers/llvm-dlltool/Options.td
+++ b/llvm/lib/ToolDrivers/llvm-dlltool/Options.td
@@ -15,6 +15,9 @@
 def k: Flag<["-"], "k">, HelpText<"Kill @n Symbol from export">;
 def k_alias: Flag<["--"], "kill-at">, Alias<k>;
 
+def no_leading_underscore: Flag<["--"], "no-leading-underscore">,
+    HelpText<"Don't add leading underscores on symbols">;
+
 //==============================================================================
 // The flags below do nothing. They are defined only for dlltool compatibility.
 //==============================================================================
diff --git a/llvm/test/tools/llvm-dlltool/no-leading-underscore.def b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
@@ -0,0 +1,19 @@
+; RUN: llvm-dlltool -k -m i386 --input-def %s --output-lib %t.a --no-leading-underscore --kill-at
+; RUN: llvm-readobj %t.a | FileCheck %s
+; RUN: llvm-nm %t.a | FileCheck %s -check-prefix=CHECK-NM
+
+LIBRARY test.dll
+EXPORTS
+func
+alias == func
+DecoratedFunction@4
+
+; CHECK:      Name type: name
+; CHECK-NEXT: Symbol: __imp_func
+; CHECK-NEXT: Symbol: func
+; CHECK:      Name type: undecorate
+; CHECK-NEXT: Symbol: __imp_DecoratedFunction@4
+; CHECK-NEXT: Symbol: DecoratedFunction@4
+
+; CHECK-NM: W alias
+; CHECK-NM: U func