diff --git a/llvm/include/llvm/Analysis/DominanceFrontierImpl.h b/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
index 7de2227b5d92..04df2cc35d46 100644
--- a/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
+++ b/llvm/include/llvm/Analysis/DominanceFrontierImpl.h
@@ -47,6 +47,14 @@ void DominanceFrontierBase<BlockT>::removeBlock(BlockT *BB) {
   Frontiers.erase(BB);
 }
 
+template <class BlockT>
+void DominanceFrontierBase<BlockT>::addToFrontier(iterator I,
+                                                  BlockT *Node) {
+  assert(I != end() && "BB is not in DominanceFrontier!");
+  assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
+  I->second.erase(Node);
+}
+
 template <class BlockT>
 void DominanceFrontierBase<BlockT>::removeFromFrontier(iterator I,
                                                        BlockT *Node) {