diff --git a/llvm/include/llvm/ADT/StringMap.h b/llvm/include/llvm/ADT/StringMap.h
index 097418efc817966de8fb02504b0d16bfb2881bc3..b4497a276d0e58331f54b528dd9b0e6353f87336 100644
--- a/llvm/include/llvm/ADT/StringMap.h
+++ b/llvm/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!");