Index: lib/Transforms/Utils/BasicBlockUtils.cpp
===================================================================
--- lib/Transforms/Utils/BasicBlockUtils.cpp
+++ lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -38,6 +38,8 @@
 #include "llvm/IR/Value.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/Casting.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <cassert>
 #include <cstdint>
@@ -47,6 +49,8 @@
 
 using namespace llvm;
 
+#define DEBUG_TYPE "basicblock-utils"
+
 void llvm::DetatchDeadBlocks(
     ArrayRef<BasicBlock *> BBs,
     SmallVectorImpl<DominatorTree::UpdateType> *Updates,
@@ -190,6 +194,9 @@
       if (IncValue == &PN)
         return false;
 
+  LLVM_DEBUG(dbgs() << "Merging: " << BB->getName() << " into "
+                    << PredBB->getName() << "\n");
+
   // Begin by getting rid of unneeded PHIs.
   SmallVector<AssertingVH<Value>, 4> IncomingValues;
   if (isa<PHINode>(BB->front())) {
Index: lib/Transforms/Utils/LoopUnroll.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnroll.cpp
+++ lib/Transforms/Utils/LoopUnroll.cpp
@@ -818,12 +818,14 @@
   assert(!DT || !UnrollVerifyDomtree ||
       DT->verify(DominatorTree::VerificationLevel::Fast));
 
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
   // Merge adjacent basic blocks, if possible.
   for (BasicBlock *Latch : Latches) {
     BranchInst *Term = cast<BranchInst>(Latch->getTerminator());
     if (Term->isUnconditional()) {
       BasicBlock *Dest = Term->getSuccessor(0);
-      if (BasicBlock *Fold = foldBlockIntoPredecessor(Dest, LI, SE, DT)) {
+      BasicBlock *Fold = Dest->getUniquePredecessor();
+      if (MergeBlockIntoPredecessor(Dest, &DTU, LI)) {
         // Dest has been folded into Fold. Update our worklists accordingly.
         std::replace(Latches.begin(), Latches.end(), Dest, Fold);
         UnrolledLoopBlocks.erase(std::remove(UnrolledLoopBlocks.begin(),
Index: lib/Transforms/Utils/LoopUnrollAndJam.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnrollAndJam.cpp
+++ lib/Transforms/Utils/LoopUnrollAndJam.cpp
@@ -538,12 +538,14 @@
   MergeBlocks.insert(ForeBlocksLast.begin(), ForeBlocksLast.end());
   MergeBlocks.insert(SubLoopBlocksLast.begin(), SubLoopBlocksLast.end());
   MergeBlocks.insert(AftBlocksLast.begin(), AftBlocksLast.end());
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
   while (!MergeBlocks.empty()) {
     BasicBlock *BB = *MergeBlocks.begin();
     BranchInst *Term = dyn_cast<BranchInst>(BB->getTerminator());
     if (Term && Term->isUnconditional() && L->contains(Term->getSuccessor(0))) {
       BasicBlock *Dest = Term->getSuccessor(0);
-      if (BasicBlock *Fold = foldBlockIntoPredecessor(Dest, LI, SE, DT)) {
+      BasicBlock *Fold = Dest->getUniquePredecessor();
+      if (MergeBlockIntoPredecessor(Dest, &DTU, LI)) {
         // Don't remove BB and add Fold as they are the same BB
         assert(Fold == BB);
         (void)Fold;
Index: test/CodeGen/AArch64/loop-micro-op-buffer-size-t99.ll
===================================================================
--- test/CodeGen/AArch64/loop-micro-op-buffer-size-t99.ll
+++ test/CodeGen/AArch64/loop-micro-op-buffer-size-t99.ll
@@ -1,5 +1,5 @@
 ; REQUIRES: asserts
-; RUN: opt -mcpu=thunderx2t99 -loop-unroll --debug-only=loop-unroll -S -unroll-allow-partial < %s 2>&1 | FileCheck %s
+; RUN: opt -mcpu=thunderx2t99 -loop-unroll --debug-only=loop-unroll --debug-only=basicblock-utils -S -unroll-allow-partial < %s 2>&1 | FileCheck %s
 
 target triple = "aarch64-unknown-linux-gnu"