diff --git a/include/llvm/ADT/StringMap.h b/include/llvm/ADT/StringMap.h
index 097418efc81..b4497a276d0 100644
--- a/include/llvm/ADT/StringMap.h
+++ b/include/llvm/ADT/StringMap.h
@@ -239,7 +239,7 @@ public:
   explicit StringMap(AllocatorTy A)
     : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))), Allocator(A) {}
 
-  explicit StringMap(const StringMap &RHS)
+  StringMap(const StringMap &RHS)
     : StringMapImpl(static_cast<unsigned>(sizeof(MapEntryTy))) {
     assert(RHS.empty() &&
            "Copy ctor from non-empty stringmap not implemented yet!");