Index: llvm/lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- llvm/lib/LTO/LTOCodeGenerator.cpp
+++ llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -410,6 +410,7 @@
 
   // Declare a callback for the internalize pass that will ask for every
   // candidate GlobalValue if it can be internalized or not.
+  Mangler Mang;
   SmallString<64> MangledName;
   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
     // Unnamed globals can't be mangled, but they can't be preserved either.
@@ -421,8 +422,7 @@
     // underscore.
     MangledName.clear();
     MangledName.reserve(GV.getName().size() + 1);
-    Mangler::getNameWithPrefix(MangledName, GV.getName(),
-                               MergedModule->getDataLayout());
+    Mang.getNameWithPrefix(MangledName, &GV, false);
     return MustPreserveSymbols.count(MangledName);
   };
 
Index: llvm/test/LTO/X86/stdcall.ll
===================================================================
--- /dev/null
+++ llvm/test/LTO/X86/stdcall.ll
@@ -0,0 +1,10 @@
+; RUN: llvm-as < %s > %t
+; RUN: llvm-lto -exported-symbol=_DllMain@12 -filetype=asm -o - %t | FileCheck %s
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i386-pc-windows-msvc19.0.23918"
+
+; CHECK: .globl _DllMain@12
+define x86_stdcallcc i32 @DllMain(i8* %module, i32 %reason, i8* %reserved) {
+  ret i32 1
+}