Index: llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
===================================================================
--- llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
+++ llvm/trunk/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
@@ -171,6 +171,7 @@
       // By making sure E.SymbolName != E.Name for decorated symbols,
       // writeImportLibrary writes these symbols with the type
       // IMPORT_NAME_UNDECORATE.
+      E.ExtName = E.ExtName.substr(0, E.ExtName.find('@', 1));
     }
   }
 
Index: llvm/trunk/test/tools/llvm-dlltool/coff-decorated.def
===================================================================
--- llvm/trunk/test/tools/llvm-dlltool/coff-decorated.def
+++ llvm/trunk/test/tools/llvm-dlltool/coff-decorated.def
@@ -9,6 +9,7 @@
 @FastcallFunction@4
 StdcallAlias@4==StdcallFunction@4
 ??_7exception@@6B@
+StdcallExportName@4=StdcallInternalFunction@4
 
 ; CHECK: Name type: noprefix
 ; CHECK: Symbol: __imp__CdeclFunction
@@ -24,3 +25,5 @@
 ; CHECK: Symbol: ??_7exception@@6B@
 ; CHECK-NM: W _StdcallAlias@4
 ; CHECK-NM: U _StdcallFunction@4
+; CHECK: Symbol: __imp__StdcallExportName@4{{$}}
+; CHECK: Symbol: _StdcallExportName@4{{$}}