diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp
index 5e3a638809494..7ded51d9e3abd 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -1004,13 +1004,9 @@ static void replaceVPBBWithIRVPBB(VPBasicBlock *VPBB, BasicBlock *IRBB) {
     assert(!R.isPhi() && "Tried to move phi recipe to end of block");
     R.moveBefore(*IRVPBB, IRVPBB->end());
   }
-  VPBlockBase *PredVPBB = VPBB->getSinglePredecessor();
-  VPBlockUtils::disconnectBlocks(PredVPBB, VPBB);
-  VPBlockUtils::connectBlocks(PredVPBB, IRVPBB);
-  for (auto *Succ : to_vector(VPBB->getSuccessors())) {
-    VPBlockUtils::connectBlocks(IRVPBB, Succ);
-    VPBlockUtils::disconnectBlocks(VPBB, Succ);
-  }
+
+  VPBlockUtils::reassociateBlocks(VPBB, IRVPBB);
+
   delete VPBB;
 }
 
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 8c5246d613c13..c5b3ea1b1d245 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -440,6 +440,26 @@ class VPBlockBase {
     Successors.erase(Pos);
   }
 
+  /// This function replaces one predecessor with another, useful when
+  /// trying to replace an old block in the CFG with a new one.
+  void replacePredecessor(VPBlockBase *Old, VPBlockBase *New) {
+    auto I = find(Predecessors, Old);
+    assert(I != Predecessors.end());
+    assert(Old->getParent() == New->getParent() &&
+           "replaced predecessor must have the same parent");
+    *I = New;
+  }
+
+  /// This function replaces one successor with another, useful when
+  /// trying to replace an old block in the CFG with a new one.
+  void replaceSuccessor(VPBlockBase *Old, VPBlockBase *New) {
+    auto I = find(Successors, Old);
+    assert(I != Successors.end());
+    assert(Old->getParent() == New->getParent() &&
+           "replaced successor must have the same parent");
+    *I = New;
+  }
+
 protected:
   VPBlockBase(const unsigned char SC, const std::string &N)
       : SubclassID(SC), Name(N) {}
@@ -3862,6 +3882,19 @@ class VPBlockUtils {
     To->removePredecessor(From);
   }
 
+  /// Reassociate all the blocks connected to \p Old so that they now point to
+  /// \p New.
+  static void reassociateBlocks(VPBlockBase *Old, VPBlockBase *New) {
+    for (auto *Pred : to_vector(Old->getPredecessors()))
+      Pred->replaceSuccessor(Old, New);
+    for (auto *Succ : to_vector(Old->getSuccessors()))
+      Succ->replacePredecessor(Old, New);
+    New->setPredecessors(Old->getPredecessors());
+    New->setSuccessors(Old->getSuccessors());
+    Old->clearPredecessors();
+    Old->clearSuccessors();
+  }
+
   /// Return an iterator range over \p Range which only includes \p BlockTy
   /// blocks. The accesses are casted to \p BlockTy.
   template <typename BlockTy, typename T>