Index: lld/COFF/Config.h
===================================================================
--- lld/COFF/Config.h
+++ lld/COFF/Config.h
@@ -90,6 +90,7 @@
   bool NoEntry = false;
   std::string OutputFile;
   std::string ImportName;
+  bool Demangle = true;
   bool DoGC = true;
   bool DoICF = true;
   bool TailMerge;
Index: lld/COFF/Driver.cpp
===================================================================
--- lld/COFF/Driver.cpp
+++ lld/COFF/Driver.cpp
@@ -1081,6 +1081,9 @@
     Config->Incremental = true;
   }
 
+  // Handle /demangle
+  Config->Demangle = Args.hasFlag(OPT_demangle, OPT_demangle_no);
+
   // Handle /debugtype
   Config->DebugTypes = parseDebugTypes(Args);
 
Index: lld/COFF/Options.td
===================================================================
--- lld/COFF/Options.td
+++ lld/COFF/Options.td
@@ -154,6 +154,9 @@
 // LLD extensions
 def exclude_all_symbols : F<"exclude-all-symbols">;
 def export_all_symbols : F<"export-all-symbols">;
+defm demangle : B<"demangle",
+    "Demangle symbols in output (default)",
+    "Do not demangle symbols in output">;
 def kill_at : F<"kill-at">;
 def lldmingw : F<"lldmingw">;
 def output_def : Joined<["/", "-"], "output-def:">;
@@ -178,11 +181,6 @@
 
 class QF<string name> : Joined<["/", "-", "-?"], name#":">;
 
-multiclass QB<string name> {
-  def "" : F<name>;
-  def _no : F<name#":no">;
-}
-
 def ignoreidl : F<"ignoreidl">;
 def nologo : F<"nologo">;
 def throwingnew : F<"throwingnew">;
Index: lld/COFF/Symbols.cpp
===================================================================
--- lld/COFF/Symbols.cpp
+++ lld/COFF/Symbols.cpp
@@ -20,8 +20,9 @@
 
 // Returns a symbol name for an error message.
 std::string lld::toString(coff::Symbol &B) {
-  if (Optional<std::string> S = lld::demangleMSVC(B.getName()))
-    return ("\"" + *S + "\" (" + B.getName() + ")").str();
+  if (coff::Config->Demangle)
+    if (Optional<std::string> S = lld::demangleMSVC(B.getName()))
+      return *S;
   return B.getName();
 }
 
Index: lld/test/COFF/undefined-symbol-cv.s
===================================================================
--- lld/test/COFF/undefined-symbol-cv.s
+++ lld/test/COFF/undefined-symbol-cv.s
@@ -2,19 +2,19 @@
 # RUN: llvm-mc -triple=x86_64-windows-msvc -filetype=obj -o %t.obj %s
 # RUN: not lld-link /out:%t.exe %t.obj 2>&1 | FileCheck %s
 
-# CHECK: error: undefined symbol: "int __cdecl foo(void)" (?foo@@YAHXZ)
+# CHECK: error: undefined symbol: int __cdecl foo(void)
 # CHECK-NEXT: >>> referenced by file1.cpp:1
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by file1.cpp:2
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
 # CHECK-EMPTY:
-# CHECK-NEXT: error: undefined symbol: "int __cdecl bar(void)" (?bar@@YAHXZ)
+# CHECK-NEXT: error: undefined symbol: int __cdecl bar(void)
 # CHECK-NEXT: >>> referenced by file2.cpp:3
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by file1.cpp:4
 # CHECK-NEXT: >>>               {{.*}}.obj:(f1)
 # CHECK-EMPTY:
-# CHECK-NEXT: error: undefined symbol: "int __cdecl baz(void)" (?baz@@YAHXZ)
+# CHECK-NEXT: error: undefined symbol: int __cdecl baz(void)
 # CHECK-NEXT: >>> referenced by file1.cpp:5
 # CHECK-NEXT: >>>               {{.*}}.obj:(f2)
 
Index: lld/test/COFF/undefined-symbol.s
===================================================================
--- lld/test/COFF/undefined-symbol.s
+++ lld/test/COFF/undefined-symbol.s
@@ -1,16 +1,22 @@
 # REQUIRES: x86
 # RUN: llvm-mc -triple=x86_64-windows-msvc -filetype=obj -o %t.obj %s
 # RUN: not lld-link /out:%t.exe %t.obj 2>&1 | FileCheck %s
+# RUN: not lld-link /out:%t.exe /demangle %t.obj 2>&1 | FileCheck %s
+# RUN: not lld-link /out:%t.exe /demangle:no %t.obj 2>&1 | FileCheck --check-prefix=NODEMANGLE %s
 
-# CHECK: error: undefined symbol: "int __cdecl foo(void)" (?foo@@YAHXZ)
+# NODEMANGLE: error: undefined symbol: ?foo@@YAHXZ
+# NODEMANGLE: error: undefined symbol: ?bar@@YAHXZ
+# NODEMANGLE: error: undefined symbol: __imp_?baz@@YAHXZ
+
+# CHECK: error: undefined symbol: int __cdecl foo(void)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
 # CHECK-EMPTY:
-# CHECK-NEXT: error: undefined symbol: "int __cdecl bar(void)" (?bar@@YAHXZ)
+# CHECK-NEXT: error: undefined symbol: int __cdecl bar(void)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(f1)
 # CHECK-EMPTY:
-# CHECK-NEXT: error: undefined symbol: "__declspec(dllimport) int __cdecl baz(void)" (__imp_?baz@@YAHXZ)
+# CHECK-NEXT: error: undefined symbol: __declspec(dllimport) int __cdecl baz(void)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(f2)
 
         .section        .text,"xr",one_only,main