diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 443a620d1af..7bfa8b22f7a 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -584,6 +584,8 @@ public:
   }
 
   void swap(DenseMap& RHS) {
+    this->incrementEpoch();
+    RHS.incrementEpoch();
     std::swap(Buckets, RHS.Buckets);
     std::swap(NumEntries, RHS.NumEntries);
     std::swap(NumTombstones, RHS.NumTombstones);