Index: llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
===================================================================
--- llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
+++ llvm/include/llvm/Transforms/Scalar/LoopPassManager.h
@@ -356,6 +356,14 @@
     Worklist.insert(CurrentL);
   }
 
+  bool isLoopNestChanged() const {
+    return LoopNestChanged;
+  }
+
+  void markLoopNestChanged(bool Changed) {
+    LoopNestChanged = Changed;
+  }
+
 private:
   friend class llvm::FunctionToLoopPassAdaptor;
 
@@ -368,6 +376,7 @@
   Loop *CurrentL;
   bool SkipCurrentLoop;
   const bool LoopNestMode;
+  bool LoopNestChanged;
 
 #ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
   // In debug builds we also track the parent loop to implement asserts even in
@@ -376,8 +385,10 @@
 #endif
 
   LPMUpdater(SmallPriorityWorklist<Loop *, 4> &Worklist,
-             LoopAnalysisManager &LAM, bool LoopNestMode = false)
-      : Worklist(Worklist), LAM(LAM), LoopNestMode(LoopNestMode) {}
+             LoopAnalysisManager &LAM, bool LoopNestMode = false,
+             bool LoopNestChanged=false)
+      : Worklist(Worklist), LAM(LAM), LoopNestMode(LoopNestMode),
+        LoopNestChanged(LoopNestChanged) {}
 };
 
 template <typename IRUnitT, typename PassT>
Index: llvm/lib/Analysis/LoopNestAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/LoopNestAnalysis.cpp
+++ llvm/lib/Analysis/LoopNestAnalysis.cpp
@@ -450,6 +450,12 @@
   return OS;
 }
 
+LoopNestAnalysis::Result
+LoopNestAnalysis::run(Loop &L, LoopAnalysisManager &AM,
+                      LoopStandardAnalysisResults &AR) {
+  return LoopNest(L, AR.SE);
+}
+
 //===----------------------------------------------------------------------===//
 // LoopNestPrinterPass implementation
 //
Index: llvm/lib/Passes/PassRegistry.def
===================================================================
--- llvm/lib/Passes/PassRegistry.def
+++ llvm/lib/Passes/PassRegistry.def
@@ -492,6 +492,7 @@
 LOOP_ANALYSIS("ddg", DDGAnalysis())
 LOOP_ANALYSIS("iv-users", IVUsersAnalysis())
 LOOP_ANALYSIS("pass-instrumentation", PassInstrumentationAnalysis(PIC))
+LOOP_ANALYSIS("loop-nest", LoopNestAnalysis())
 #undef LOOP_ANALYSIS
 
 #ifndef LOOP_PASS
Index: llvm/lib/Transforms/Scalar/LoopInterchange.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -44,6 +44,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Scalar/LoopPassManager.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include <cassert>
@@ -1773,5 +1774,6 @@
   OptimizationRemarkEmitter ORE(&F);
   if (!LoopInterchange(&AR.SE, &AR.LI, &DI, &AR.DT, CC, &ORE).run(LN))
     return PreservedAnalyses::all();
+  U.markLoopNestChanged(true);
   return getLoopPassPreservedAnalyses();
 }
Index: llvm/lib/Transforms/Scalar/LoopPassManager.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopPassManager.cpp
+++ llvm/lib/Transforms/Scalar/LoopPassManager.cpp
@@ -78,12 +78,7 @@
 
   unsigned LoopPassIndex = 0, LoopNestPassIndex = 0;
 
-  // `LoopNestPtr` points to the `LoopNest` object for the current top-level
-  // loop and `IsLoopNestPtrValid` indicates whether the pointer is still valid.
-  // The `LoopNest` object will have to be re-constructed if the pointer is
-  // invalid when encountering a loop-nest pass.
-  std::unique_ptr<LoopNest> LoopNestPtr;
-  bool IsLoopNestPtrValid = false;
+  Loop *OuterMostLoop = &L;
 
   for (size_t I = 0, E = IsLoopNestPass.size(); I != E; ++I) {
     Optional<PreservedAnalyses> PassPA;
@@ -94,14 +89,17 @@
     } else {
       // The `I`-th pass is a loop-nest pass.
       auto &Pass = LoopNestPasses[LoopNestPassIndex++];
-
-      // If the loop-nest object calculated before is no longer valid,
-      // re-calculate it here before running the loop-nest pass.
-      if (!IsLoopNestPtrValid) {
-        LoopNestPtr = LoopNest::getLoopNest(L, AR.SE);
-        IsLoopNestPtrValid = true;
+      assert(OuterMostLoop->isOutermost() &&
+             "LoopNest should be constructed only with the outermost loop!");
+      LoopNest &LN = AM.getResult<LoopNestAnalysis>(*OuterMostLoop, AR);
+      PassPA = runSinglePass(LN, Pass, AM, AR, U, PI);
+
+      // Restore the correct loopnest status.
+      if (U.isLoopNestChanged()) {
+        while (auto *PL = OuterMostLoop->getParentLoop())
+          OuterMostLoop = PL;
+        U.markLoopNestChanged(false);
       }
-      PassPA = runSinglePass(*LoopNestPtr, Pass, AM, AR, U, PI);
     }
 
     // `PassPA` is `None` means that the before-pass callbacks in
@@ -124,9 +122,6 @@
     // aggregate preserved set for this pass manager.
     PA.intersect(std::move(*PassPA));
 
-    // Check if the current pass preserved the loop-nest object or not.
-    IsLoopNestPtrValid &= PassPA->getChecker<LoopNestAnalysis>().preserved();
-
     // 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.
Index: llvm/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
===================================================================
--- llvm/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
+++ llvm/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
@@ -301,6 +301,8 @@
     // Register our mock analysis.
     LAM.registerPass([&] { return MLAHandle.getAnalysis(); });
 
+    LAM.registerPass([&] { return LoopNestAnalysis(); });
+
     // We need DominatorTreeAnalysis for LoopAnalysis.
     FAM.registerPass([&] { return DominatorTreeAnalysis(); });
     FAM.registerPass([&] { return LoopAnalysis(); });