diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -562,8 +562,6 @@
   LPM1.addPass(LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap));
   LPM1.addPass(SimpleLoopUnswitchPass());
 
-  if (EnableLoopFlatten)
-    FPM.addPass(LoopFlattenPass());
   LPM2.addPass(LoopIdiomRecognizePass());
   LPM2.addPass(IndVarSimplifyPass());
 
@@ -594,6 +592,8 @@
       DebugLogging));
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
+  if (EnableLoopFlatten)
+    FPM.addPass(LoopFlattenPass());
   // The loop passes in LPM2 (LoopFullUnrollPass) do not preserve MemorySSA.
   // *All* loop passes must preserve it, in order to be able to use it.
   FPM.addPass(createFunctionToLoopPassAdaptor(
@@ -756,6 +756,8 @@
       DebugLogging));
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
+  if (EnableLoopFlatten)
+    FPM.addPass(LoopFlattenPass());
   // The loop passes in LPM2 (LoopIdiomRecognizePass, IndVarSimplifyPass,
   // LoopDeletionPass and LoopFullUnrollPass) do not preserve MemorySSA.
   // *All* loop passes must preserve it, in order to be able to use it.