Index: llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -1317,10 +1317,11 @@
       MCSymbol *Sym = TM.getSymbol(ComdatGV);
       StringRef COMDATSymName = Sym->getName();
 
-      // Append "$symbol" to the section name when targetting mingw. The ld.bfd
+      // Append "$symbol" to the section name *before* IR-level mangling is
+      // applied when targetting mingw. This is what GCC does, and the ld.bfd
       // COFF linker will not properly handle comdats otherwise.
       if (getTargetTriple().isWindowsGNUEnvironment())
-        raw_svector_ostream(Name) << '$' << COMDATSymName;
+        raw_svector_ostream(Name) << '$' << ComdatGV->getName();
 
       return getContext().getCOFFSection(Name, Characteristics, Kind,
                                          COMDATSymName, Selection, UniqueID);
Index: llvm/trunk/test/CodeGen/X86/mingw-comdats.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/mingw-comdats.ll
+++ llvm/trunk/test/CodeGen/X86/mingw-comdats.ll
@@ -1,13 +1,14 @@
-; RUN: llc -mtriple=x86_64-windows-itanium < %s | FileCheck %s
-; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s
-; RUN: llc -mtriple=x86_64-w64-windows-gnu < %s | FileCheck %s --check-prefix=GNU
-; RUN: llc -mtriple=i686-w64-windows-gnu < %s | FileCheck %s --check-prefix=GNU32
-; RUN: llc -mtriple=x86_64-w64-windows-gnu < %s -filetype=obj | llvm-objdump - -headers | FileCheck %s --check-prefix=GNUOBJ
+; RUN: llc -function-sections -mtriple=x86_64-windows-itanium < %s | FileCheck %s
+; RUN: llc -function-sections -mtriple=x86_64-windows-msvc < %s | FileCheck %s
+; RUN: llc -function-sections -mtriple=x86_64-w64-windows-gnu < %s | FileCheck %s --check-prefix=GNU
+; RUN: llc -function-sections -mtriple=i686-w64-windows-gnu < %s | FileCheck %s --check-prefix=GNU32
+; RUN: llc -function-sections -mtriple=x86_64-w64-windows-gnu < %s -filetype=obj | llvm-objdump - -headers | FileCheck %s --check-prefix=GNUOBJ
 
 ; GCC and MSVC handle comdats completely differently. Make sure we do the right
 ; thing for each.
 
-; Generated with this C++ source:
+; Modeled on this C++ source, with additional modifications for
+; -ffunction-sections:
 ; int bar(int);
 ; __declspec(selectany) int gv = 42;
 ; inline int foo(int x) { return bar(x) + gv; }
@@ -26,8 +27,24 @@
   ret i32 %call
 }
 
+; CHECK: .section        .text,"xr",one_only,main
 ; CHECK: main:
+; GNU: .section        .text$main,"xr",one_only,main
 ; GNU: main:
+; GNU32: .section        .text$main,"xr",one_only,_main
+; GNU32: _main:
+
+define dso_local x86_fastcallcc i32 @fastcall(i32 %x, i32 %y) {
+  %rv = add i32 %x, %y
+  ret i32 %rv
+}
+
+; CHECK: .section        .text,"xr",one_only,fastcall
+; CHECK: fastcall:
+; GNU: .section        .text$fastcall,"xr",one_only,fastcall
+; GNU: fastcall:
+; GNU32: .section        .text$fastcall,"xr",one_only,@fastcall@8
+; GNU32: @fastcall@8:
 
 ; Function Attrs: inlinehint uwtable
 define linkonce_odr dso_local i32 @_Z3fooi(i32 %x) #1 comdat {
@@ -50,9 +67,9 @@
 ; GNU: gv:
 ; GNU: .long 42
 
-; GNU32: .section        .text$__Z3fooi,"xr",discard,__Z3fooi
+; GNU32: .section        .text$_Z3fooi,"xr",discard,__Z3fooi
 ; GNU32: __Z3fooi:
-; GNU32: .section        .data$_gv,"dw",discard,_gv
+; GNU32: .section        .data$gv,"dw",discard,_gv
 ; GNU32: _gv:
 ; GNU32: .long 42