Index: lib/Transforms/Utils/LoopUnrollRuntime.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -849,16 +849,18 @@
    // the remainder code), we set the immediate dominator as the preheader.
    if (DT) {
      DT->changeImmediateDominator(BB, PreHeader);
-     // Also update the IDom for immediate successors of BB.  If the current
-     // IDom is the header, update the IDom to be the preheader because that is
-     // the nearest common dominator of all predecessors of SuccBB.  We need to
-     // check for IDom being the header because successors of exit blocks can
-     // have edges from outside the loop, and we should not incorrectly update
-     // the IDom in that case.
+     // Also update the IDom for immediate successors of BB to the Preheader,
+     // where applicable.
      for (BasicBlock *SuccBB: successors(BB))
        if (ImmediateSuccessorsOfExitBlocks.insert(SuccBB).second) {
-         if (DT->getNode(SuccBB)->getIDom()->getBlock() == Header) {
-           assert(!SuccBB->getSinglePredecessor() &&
+         // If the current IDom of SuccBB is within the loop, update the IDom to
+         // be the preheader because that is the nearest common dominator of all
+         // predecessors of SuccBB (i.e. BB and other blocks from the loop).
+         // We need to check for IDom being in the loop because successors of
+         // exit blocks can have edges from outside the loop, and we should not
+         // incorrectly update the IDom in that case.
+         if (LI->getLoopFor(DT->getNode(SuccBB)->getIDom()->getBlock()) == L) {
+           assert(!SuccBB->getUniquePredecessor() &&
                   "BB should be the IDom then!");
            DT->changeImmediateDominator(SuccBB, PreHeader);
          }
Index: test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll
===================================================================
--- test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll
+++ test/Transforms/LoopUnroll/runtime-loop-multiexit-dom-verify.ll
@@ -124,3 +124,50 @@
 exitsucc:                                              ; preds = %headerexit
   ret i64 96
 }
+
+; exit block (%default) has an exiting block and another exit block as predecessors.
+define void @test4(i16 %c3) {
+; CHECK-LABEL: test4
+
+; CHECK-LABEL: exiting.prol:
+; CHECK-NEXT:   switch i16 %c3, label %default.loopexit.loopexit1 [
+
+; CHECK-LABEL: exiting:
+; CHECK-NEXT:   switch i16 %c3, label %default.loopexit.loopexit [
+
+; CHECK-LABEL: default.loopexit.loopexit:
+; CHECK-NEXT:   br label %default.loopexit
+
+; CHECK-LABEL: default.loopexit.loopexit1:
+; CHECK-NEXT:   br label %default.loopexit
+
+; CHECK-LABEL: default.loopexit:
+; CHECK-NEXT:   br label %default
+preheader:
+  %c1 = zext i32 undef to i64
+  br label %header
+
+header:                                       ; preds = %latch, %preheader
+  %indvars.iv = phi i64 [ 0, %preheader ], [ %indvars.iv.next, %latch ]
+  br label %exiting
+
+exiting:                                           ; preds = %header
+  switch i16 %c3, label %default [
+    i16 45, label %otherexit
+    i16 95, label %latch
+  ]
+
+latch:                                          ; preds = %exiting
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %c2 = icmp ult i64 %indvars.iv.next, %c1
+  br i1 %c2, label %header, label %latchexit
+
+latchexit:                                          ; preds = %latch
+  ret void
+
+default:                                          ; preds = %otherexit, %exiting
+  ret void
+
+otherexit:                                           ; preds = %exiting
+  br label %default
+}