diff --git a/llvm/lib/Transforms/Utils/LoopPeel.cpp b/llvm/lib/Transforms/Utils/LoopPeel.cpp
--- a/llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -11,6 +11,7 @@
 
 #include "llvm/Transforms/Utils/LoopPeel.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -667,36 +668,8 @@
   SmallVector<std::pair<BasicBlock *, BasicBlock *>, 4> ExitEdges;
   L->getExitEdges(ExitEdges);
 
-  DenseMap<BasicBlock *, BasicBlock *> ExitIDom;
-  if (DT) {
-    // We'd like to determine the idom of exit block after peeling one
-    // iteration.
-    // Let Exit is exit block.
-    // Let ExitingSet - is a set of predecessors of Exit block. They are exiting
-    // blocks.
-    // Let Latch' and ExitingSet' are copies after a peeling.
-    // We'd like to find an idom'(Exit) - idom of Exit after peeling.
-    // It is an evident that idom'(Exit) will be the nearest common dominator
-    // of ExitingSet and ExitingSet'.
-    // idom(Exit) is a nearest common dominator of ExitingSet.
-    // idom(Exit)' is a nearest common dominator of ExitingSet'.
-    // Taking into account that we have a single Latch, Latch' will dominate
-    // Header and idom(Exit).
-    // So the idom'(Exit) is nearest common dominator of idom(Exit)' and Latch'.
-    // All these basic blocks are in the same loop, so what we find is
-    // (nearest common dominator of idom(Exit) and Latch)'.
-    // In the loop below we remember nearest common dominator of idom(Exit) and
-    // Latch to update idom of Exit later.
-    assert(L->hasDedicatedExits() && "No dedicated exits?");
-    for (auto Edge : ExitEdges) {
-      if (ExitIDom.count(Edge.second))
-        continue;
-      BasicBlock *BB = DT->findNearestCommonDominator(
-          DT->getNode(Edge.second)->getIDom()->getBlock(), Latch);
-      assert(L->contains(BB) && "IDom is not in a loop");
-      ExitIDom[Edge.second] = BB;
-    }
-  }
+  SmallDenseSet<std::pair<BasicBlock *, BasicBlock *>, 4> ExitEdgesSet(
+      ExitEdges.begin(), ExitEdges.end());
 
   Function *F = Header->getParent();
 
@@ -769,6 +742,8 @@
   SmallVector<MDNode *, 6> LoopLocalNoAliasDeclScopes;
   identifyNoAliasScopesToClone(L->getBlocks(), LoopLocalNoAliasDeclScopes);
 
+  SmallVector<DominatorTree::UpdateType, 8> DTUpdates;
+
   // For each peeled-off iteration, make a copy of the loop.
   for (unsigned Iter = 0; Iter < PeelCount; ++Iter) {
     SmallVector<BasicBlock *, 8> NewBlocks;
@@ -782,18 +757,11 @@
     // previous one.
     remapInstructionsInBlocks(NewBlocks, VMap);
 
-    if (DT) {
-      // Latches of the cloned loops dominate over the loop exit, so idom of the
-      // latter is the first cloned loop body, as original PreHeader dominates
-      // the original loop body.
-      if (Iter == 0)
-        for (auto Exit : ExitIDom)
-          DT->changeImmediateDominator(Exit.first,
-                                       cast<BasicBlock>(LVMap[Exit.second]));
-#ifdef EXPENSIVE_CHECKS
-      assert(DT->verify(DominatorTree::VerificationLevel::Fast));
-#endif
-    }
+    // If DT is available, insert edges from cloned exiting blocks to the exits
+    if (DT)
+      for (auto Exit : ExitEdgesSet)
+        DTUpdates.push_back(
+            {DT->Insert, cast<BasicBlock>(LVMap[Exit.first]), Exit.second});
 
     auto *LatchBRCopy = cast<BranchInst>(VMap[LatchBR]);
     updateBranchWeights(InsertBot, LatchBRCopy, ExitWeight, FallThroughWeight);
@@ -836,6 +804,8 @@
   // We modified the loop, update SE.
   SE->forgetTopmostLoop(L);
 
+  DT->applyUpdates(DTUpdates);
+
   // Finally DomtTree must be correct.
   assert(DT->verify(DominatorTree::VerificationLevel::Fast));