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
@@ -193,7 +193,7 @@
                 LoopStandardAnalysisResults &AR, LPMUpdater &U,
                 PassInstrumentation &PI);
 
-  PreservedAnalyses runWithLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
+  PreservedAnalyses runWithLoopNestPasses(Loop *L, LoopAnalysisManager &AM,
                                           LoopStandardAnalysisResults &AR,
                                           LPMUpdater &U);
   PreservedAnalyses runWithoutLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
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
@@ -28,7 +28,7 @@
                                LoopStandardAnalysisResults &AR, LPMUpdater &U) {
   // Runs loop-nest passes only when the current loop is a top-level one.
   PreservedAnalyses PA = (L.isOutermost() && !LoopNestPasses.empty())
-                             ? runWithLoopNestPasses(L, AM, AR, U)
+                             ? runWithLoopNestPasses(&L, AM, AR, U)
                              : runWithoutLoopNestPasses(L, AM, AR, U);
 
   // Invalidation for the current loop should be handled above, and other loop
@@ -65,16 +65,16 @@
 
 // Run both loop passes and loop-nest passes on top-level loop \p L.
 PreservedAnalyses
-LoopPassManager::runWithLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
+LoopPassManager::runWithLoopNestPasses(Loop *L, LoopAnalysisManager &AM,
                                        LoopStandardAnalysisResults &AR,
                                        LPMUpdater &U) {
-  assert(L.isOutermost() &&
+  assert(L->isOutermost() &&
          "Loop-nest passes should only run on top-level loops.");
   PreservedAnalyses PA = PreservedAnalyses::all();
 
   // Request PassInstrumentation from analysis manager, will use it to run
   // instrumenting callbacks for the passes later.
-  PassInstrumentation PI = AM.getResult<PassInstrumentationAnalysis>(L, AR);
+  PassInstrumentation PI = AM.getResult<PassInstrumentationAnalysis>(*L, AR);
 
   unsigned LoopPassIndex = 0, LoopNestPassIndex = 0;
 
@@ -86,11 +86,17 @@
   bool IsLoopNestPtrValid = false;
 
   for (size_t I = 0, E = IsLoopNestPass.size(); I != E; ++I) {
+    // A loop nest should be constructed with the outermost loop. In case L is
+    // no longer the outermost loop after transformation, we obtain the current
+    // outermost loop.
+    while (Loop *Parent = L->getParentLoop())
+      L = Parent;
+
     Optional<PreservedAnalyses> PassPA;
     if (!IsLoopNestPass[I]) {
       // The `I`-th pass is a loop pass.
       auto &Pass = LoopPasses[LoopPassIndex++];
-      PassPA = runSinglePass(L, Pass, AM, AR, U, PI);
+      PassPA = runSinglePass(*L, Pass, AM, AR, U, PI);
     } else {
       // The `I`-th pass is a loop-nest pass.
       auto &Pass = LoopNestPasses[LoopNestPassIndex++];
@@ -98,7 +104,7 @@
       // 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);
+        LoopNestPtr = LoopNest::getLoopNest(*L, AR.SE);
         IsLoopNestPtrValid = true;
       }
       PassPA = runSinglePass(*LoopNestPtr, Pass, AM, AR, U, PI);
@@ -118,7 +124,7 @@
 
     // Update the analysis manager as each pass runs and potentially
     // invalidates analyses.
-    AM.invalidate(L, *PassPA);
+    AM.invalidate(*L, *PassPA);
 
     // Finally, we intersect the final preserved analyses to compute the
     // aggregate preserved set for this pass manager.
@@ -130,7 +136,7 @@
     // 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());
+    U.setParentLoop(L->getParentLoop());
   }
   return PA;
 }
diff --git a/llvm/test/Transforms/LoopInterchange/interchanged-loop-nest-4.ll b/llvm/test/Transforms/LoopInterchange/interchanged-loop-nest-4.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/LoopInterchange/interchanged-loop-nest-4.ll
@@ -0,0 +1,53 @@
+; REQUIRES: asserts
+; RUN: opt < %s -passes="loop(loop-interchange,loop-interchange)" -cache-line-size=8 -verify-dom-info -verify-loop-info \
+; RUN:  -debug-only=loop-interchange 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+@g_75 = external global i32, align 1
+@g_78 = external global [6 x ptr], align 1
+
+; Loop interchange as a loopnest pass should always construct the loop nest from
+; the outermost loop. This test case runs loop interchange twice. In the loop pass
+; manager, it might occur that after the first loop interchange transformation 
+; the original outermost loop becomes a inner loop hence the loop nest constructed 
+; afterwards for the second loop interchange pass turns out to be a loop list of size
+; 2 and is not valid. This causes functional issues.
+;
+; Make sure we always construct the valid and correct loop nest at the beginning 
+; of execution of a loopnest pass.
+
+; CHECK: Processing LoopList of size = 3
+; CHECK: Processing LoopList of size = 3
+define void @loopnest_01() {
+entry:
+  br label %for.cond5.preheader.i.i.i
+
+for.cond5.preheader.i.i.i:                        ; preds = %for.end16.i.i.i, %entry
+  %storemerge11.i.i.i = phi i32 [ 4, %entry ], [ %sub18.i.i.i, %for.end16.i.i.i ]
+  br label %for.cond8.preheader.i.i.i
+
+for.cond8.preheader.i.i.i:                        ; preds = %for.inc14.i.i.i, %for.cond5.preheader.i.i.i
+  %l_105.18.i.i.i = phi i16 [ 0, %for.cond5.preheader.i.i.i ], [ %add15.i.i.i, %for.inc14.i.i.i ]
+  br label %for.body10.i.i.i
+
+for.body10.i.i.i:                                 ; preds = %for.body10.i.i.i, %for.cond8.preheader.i.i.i
+  %storemerge56.i.i.i = phi i16 [ 5, %for.cond8.preheader.i.i.i ], [ %sub.i.i.i, %for.body10.i.i.i ]
+  %arrayidx.i.i.i = getelementptr [6 x ptr], ptr @g_78, i16 0, i16 %storemerge56.i.i.i
+  store ptr @g_75, ptr %arrayidx.i.i.i, align 1
+  %sub.i.i.i = add nsw i16 %storemerge56.i.i.i, -1
+  br i1 true, label %for.inc14.i.i.i, label %for.body10.i.i.i
+
+for.inc14.i.i.i:                                  ; preds = %for.body10.i.i.i
+  %add15.i.i.i = add nuw nsw i16 %l_105.18.i.i.i, 1
+  %exitcond.not.i.i.i = icmp eq i16 %add15.i.i.i, 6
+  br i1 %exitcond.not.i.i.i, label %for.end16.i.i.i, label %for.cond8.preheader.i.i.i
+
+for.end16.i.i.i:                                  ; preds = %for.inc14.i.i.i
+  %sub18.i.i.i = add nsw i32 %storemerge11.i.i.i, -1
+  %cmp.i10.not.i.i = icmp eq i32 %storemerge11.i.i.i, 0
+  br i1 %cmp.i10.not.i.i, label %func_4.exit.i, label %for.cond5.preheader.i.i.i
+
+func_4.exit.i:                                    ; preds = %for.end16.i.i.i
+  unreachable
+}