diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -673,7 +673,18 @@
       LI->removeBlock(BB);
 
     // The last step is to update LoopInfo now that we've eliminated this loop.
-    LI->erase(L);
+    // Note: LoopInfo::erase remove the given loop and relink its subloops with
+    // its parent. While removeLoop/removeChildLoop remove the given loop but
+    // not relink its subloops, which is what we want.
+    if (Loop *ParentLoop = L->getParentLoop()) {
+      Loop::iterator I = find(ParentLoop->begin(), ParentLoop->end(), L);
+      assert(I != ParentLoop->end() && "Couldn't find loop");
+      ParentLoop->removeChildLoop(I);
+    } else {
+      Loop::iterator I = find(LI->begin(), LI->end(), L);
+      assert(I != LI->end() && "Couldn't find loop");
+      LI->removeLoop(I);
+    }
   }
 }
 
diff --git a/llvm/unittests/Transforms/Utils/CMakeLists.txt b/llvm/unittests/Transforms/Utils/CMakeLists.txt
--- a/llvm/unittests/Transforms/Utils/CMakeLists.txt
+++ b/llvm/unittests/Transforms/Utils/CMakeLists.txt
@@ -15,6 +15,7 @@
   FunctionComparatorTest.cpp
   IntegerDivisionTest.cpp
   LocalTest.cpp
+  LoopUtilsTest.cpp
   SizeOptsTest.cpp
   SSAUpdaterBulkTest.cpp
   UnrollLoopTest.cpp