diff --git a/llvm/include/llvm/Transforms/Scalar/LoopPassManager.h b/llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
--- a/llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
+++ b/llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
@@ -271,6 +271,10 @@
       SkipCurrentLoop = true;
   }
 
+#ifndef NDEBUG
+  void setParentLoop(Loop *L) { ParentL = L; }
+#endif
+
   /// Loop passes should use this method to indicate they have added new child
   /// loops of the current loop.
   ///
diff --git a/llvm/lib/Transforms/Scalar/LoopPassManager.cpp b/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
--- a/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
@@ -114,6 +114,13 @@
     // Check if the current pass preserved the loop-nest object or not.
     IsLoopNestPtrValid &= PassPA->getChecker<LoopNestAnalysis>().preserved();
 
+#ifndef NDEBUG
+    // After running the loop pass, the parent loop might change and we need to
+    // notify the updater, otherwise U.ParentL might gets outdated and triggers
+    // assertion failures in addSiblingLoops and addChildLoops.
+    U.setParentLoop(L.getParentLoop());
+#endif
+
     // FIXME: Historically, the pass managers all called the LLVM context's
     // yield function here. We don't have a generic way to acquire the
     // context and it isn't yet clear what the right pattern is for yielding
@@ -158,6 +165,13 @@
     // aggregate preserved set for this pass manager.
     PA.intersect(std::move(*PassPA));
 
+#ifndef NDEBUG
+    // After running the loop pass, the parent loop might change and we need to
+    // notify the updater, otherwise U.ParentL might gets outdated and triggers
+    // assertion failures in addSiblingLoops and addChildLoops.
+    U.setParentLoop(L.getParentLoop());
+#endif
+
     // FIXME: Historically, the pass managers all called the LLVM context's
     // yield function here. We don't have a generic way to acquire the
     // context and it isn't yet clear what the right pattern is for yielding