Index: llvm/lib/Object/IRSymtab.cpp
===================================================================
--- llvm/lib/Object/IRSymtab.cpp
+++ llvm/lib/Object/IRSymtab.cpp
@@ -72,7 +72,7 @@
           BumpPtrAllocator &Alloc)
       : Symtab(Symtab), StrtabBuilder(StrtabBuilder), Saver(Alloc) {}
 
-  DenseMap<const Comdat *, unsigned> ComdatMap;
+  DenseMap<const Comdat *, int> ComdatMap;
   Mangler Mang;
   Triple TT;
 
@@ -97,6 +97,8 @@
                   reinterpret_cast<const char *>(Objs.data() + Objs.size()));
   }
 
+  Expected<int> getComdatIndex(const Comdat *C, const Module *M);
+
   Error addModule(Module *M);
   Error addSymbol(const ModuleSymbolTable &Msymtab,
                   const SmallPtrSet<GlobalValue *, 8> &Used,
@@ -140,6 +142,35 @@
   return Error::success();
 }
 
+Expected<int> Builder::getComdatIndex(const Comdat *C, const Module *M) {
+  auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
+  if (P.second) {
+    std::string Name;
+    if (TT.isOSBinFormatCOFF()) {
+      const GlobalValue *GV = M->getNamedValue(C->getName());
+      if (!GV)
+        return make_error<StringError>("Could not find leader",
+                                       inconvertibleErrorCode());
+      // Internal leaders do not affect symbol resolution, therefore they do not
+      // appear in the symbol table.
+      if (GV->hasLocalLinkage()) {
+        P.first->second = -1;
+        return -1;
+      }
+      llvm::raw_string_ostream OS(Name);
+      Mang.getNameWithPrefix(OS, GV, false);
+    } else {
+      Name = C->getName();
+    }
+
+    storage::Comdat Comdat;
+    setStr(Comdat.Name, Saver.save(Name));
+    Comdats.push_back(Comdat);
+  }
+
+  return P.first->second;
+}
+
 Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
                          const SmallPtrSet<GlobalValue *, 8> &Used,
                          ModuleSymbolTable::Symbol Msym) {
@@ -216,14 +247,10 @@
     return make_error<StringError>("Unable to determine comdat of alias!",
                                    inconvertibleErrorCode());
   if (const Comdat *C = Base->getComdat()) {
-    auto P = ComdatMap.insert(std::make_pair(C, Comdats.size()));
-    Sym.ComdatIndex = P.first->second;
-
-    if (P.second) {
-      storage::Comdat Comdat;
-      setStr(Comdat.Name, C->getName());
-      Comdats.push_back(Comdat);
-    }
+    Expected<int> ComdatIndexOrErr = getComdatIndex(C, GV->getParent());
+    if (!ComdatIndexOrErr)
+      return ComdatIndexOrErr.takeError();
+    Sym.ComdatIndex = *ComdatIndexOrErr;
   }
 
   if (TT.isOSBinFormatCOFF()) {
Index: llvm/test/LTO/Resolution/X86/symtab.ll
===================================================================
--- llvm/test/LTO/Resolution/X86/symtab.ll
+++ llvm/test/LTO/Resolution/X86/symtab.ll
@@ -17,6 +17,15 @@
   ret i32 0
 }
 
+; CHECK: D------X @fun2@8
+; CHECK-NEXT: comdat @fun2@8
+$fun2 = comdat any
+define x86_fastcallcc i32 @fun2(i32 inreg %a, i32 inreg %b) comdat {
+entry:
+  %add = add nsw i32 %b, %a
+  ret i32 %add
+}
+
 ; CHECK: H------- _g1
 @g1 = hidden global i32 0
 
@@ -43,11 +52,19 @@
 @g8 = common global i32 0, align 8
 
 ; CHECK: D------- _g9
-; CHECK-NEXT: comdat g9
+; CHECK-NEXT: comdat _g9
 $g9 = comdat any
 @g9 = global i32 0, comdat
 
-; CHECK: D--WI--- _g10
-; CHECK-NEXT: comdat g9
+; CHECK-NOT: _g10
+$g10 = comdat any
+@g10 = internal global i32 0, comdat
+
+; CHECK: D------- _g11
+; CHECK-NOT: comdat
+@g11 = global i32 0, comdat($g10)
+
+; CHECK: D--WI--- _a1
+; CHECK-NEXT: comdat _g9
 ; CHECK-NEXT: fallback _g9
-@g10 = weak alias i32, i32* @g9
+@a1 = weak alias i32, i32* @g9