Index: lib/Linker/LinkModules.cpp
===================================================================
--- lib/Linker/LinkModules.cpp
+++ lib/Linker/LinkModules.cpp
@@ -102,6 +102,9 @@
     return DGV;
   }
 
+  void dropReplacedComdat(GlobalValue &GV,
+                          const DenseSet<const Comdat *> &ReplacedDstComdats);
+
   bool linkIfNeeded(GlobalValue &GV);
 
   /// Helper method to check if we are importing from the current source
@@ -449,6 +452,38 @@
   }
 }
 
+// Drop GV if it is a member of a comdat that we are dropping. This can happen
+// with COFF's largest selection kind.
+void ModuleLinker::dropReplacedComdat(
+    GlobalValue &GV, const DenseSet<const Comdat *> &ReplacedDstComdats) {
+  Comdat *C = GV.getComdat();
+  if (!C)
+    return;
+  if (!ReplacedDstComdats.count(C))
+    return;
+  if (GV.use_empty()) {
+    GV.eraseFromParent();
+    return;
+  }
+
+  if (auto *F = dyn_cast<Function>(&GV)) {
+    F->deleteBody();
+  } else if (auto *Var = dyn_cast<GlobalVariable>(&GV)) {
+    Var->setInitializer(nullptr);
+  } else {
+    auto &Alias = cast<GlobalAlias>(GV);
+    Module &M = *Alias.getParent();
+    PointerType &Ty = *cast<PointerType>(Alias.getType());
+    GlobalValue::LinkageTypes L = Alias.getLinkage();
+    GlobalValue *Declaration =
+        new GlobalVariable(M, Ty.getElementType(), /*isConstant*/ false, L,
+                           /*Initializer*/ nullptr);
+    Declaration->takeName(&Alias);
+    Alias.replaceAllUsesWith(Declaration);
+    Alias.eraseFromParent();
+  }
+}
+
 bool ModuleLinker::run() {
   for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
     const Comdat &C = SMEC.getValue();
@@ -461,6 +496,40 @@
     ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
   }
 
+  Module &DstM = Mover.getModule();
+  DenseSet<const Comdat *> ReplacedDstComdats;
+  for (auto &P : ComdatsChosen) {
+    const Comdat *C = P.first;
+    bool LinkFromSource = P.second.second;
+    if (!LinkFromSource)
+      continue;
+
+    Module::ComdatSymTabType &ComdatSymTab = DstM.getComdatSymbolTable();
+    StringRef ComdatName = C->getName();
+    Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
+    if (DstCI == ComdatSymTab.end())
+      continue;
+
+    // The source comdat is replacing the dest one.
+    const Comdat *DstC = &DstCI->second;
+    ReplacedDstComdats.insert(DstC);
+  }
+
+  for (auto I = DstM.global_begin(), E = DstM.global_end(); I != E;) {
+    GlobalVariable &GV = *I++;
+    dropReplacedComdat(GV, ReplacedDstComdats);
+  }
+
+  for (auto I = DstM.begin(), E = DstM.end(); I != E;) {
+    Function &GV = *I++;
+    dropReplacedComdat(GV, ReplacedDstComdats);
+  }
+
+  for (auto I = DstM.alias_begin(), E = DstM.alias_end(); I != E;) {
+    GlobalAlias &GV = *I++;
+    dropReplacedComdat(GV, ReplacedDstComdats);
+  }
+
   for (GlobalVariable &GV : SrcM->globals())
     if (const Comdat *SC = GV.getComdat())
       ComdatMembers[SC].push_back(&GV);
@@ -507,7 +576,6 @@
                  },
                  ValIDToTempMDMap, false))
     return true;
-  Module &DstM = Mover.getModule();
   for (auto &P : Internalize) {
     GlobalValue *GV = DstM.getNamedValue(P.first());
     GV->setLinkage(GlobalValue::InternalLinkage);
Index: test/Linker/Inputs/comdat-rm-dst.ll
===================================================================
--- /dev/null
+++ test/Linker/Inputs/comdat-rm-dst.ll
@@ -0,0 +1,5 @@
+target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
+target triple = "i686-pc-windows-msvc"
+
+$foo = comdat largest
+@foo = global i64 43, comdat
Index: test/Linker/comdat-rm-dst.ll
===================================================================
--- /dev/null
+++ test/Linker/comdat-rm-dst.ll
@@ -0,0 +1,21 @@
+; RUN: llvm-link -S -o %t %s %p/Inputs/comdat-rm-dst.ll
+; RUN: FileCheck %s < %t
+; RUN: FileCheck --check-prefix=RM %s < %t
+
+target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
+target triple = "i686-pc-windows-msvc"
+
+$foo = comdat largest
+@foo = global i32 42, comdat
+; CHECK: @foo = global i64 43, comdat
+
+; RM-NOT: ailas
+@alias = alias i32, i32* @foo
+
+; RM-NOT: func
+define void @func() comdat($foo) {
+  ret void
+}
+
+; RM-NOT: var
+@var = global i32 42, comdat($foo)