diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index f80f6bc4ce4..f1ce23f13e0 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -1573,8 +1573,8 @@ bool ModuleLinker::run() {
     if (C.getSelectionKind() == Comdat::Any)
       continue;
     const GlobalValue *GV = SrcM->getNamedValue(C.getName());
-    assert(GV);
-    MapValue(GV, ValueMap, RF_None, &TypeMap, &ValMaterializer);
+    if (GV)
+      MapValue(GV, ValueMap, RF_None, &TypeMap, &ValMaterializer);
   }
 
   // Strip replaced subprograms before mapping any metadata -- so that we're
diff --git a/test/Linker/comdat10.ll b/test/Linker/comdat10.ll
new file mode 100644
index 00000000000..8a32c426739
--- /dev/null
+++ b/test/Linker/comdat10.ll
@@ -0,0 +1,6 @@
+; RUN: llvm-link %s /dev/null -S -o - | FileCheck %s
+
+$c = comdat largest
+
+; CHECK: @c = global i32 0, comdat
+@c = global i32 0, comdat