diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index dafb1681e837e6..b3b58d6a203d19 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -212,7 +212,6 @@ void initializeLoopGuardWideningLegacyPassPass(PassRegistry&);
 void initializeLoopIdiomRecognizeLegacyPassPass(PassRegistry&);
 void initializeLoopInfoWrapperPassPass(PassRegistry&);
 void initializeLoopInstSimplifyLegacyPassPass(PassRegistry&);
-void initializeLoopFlattenLegacyPassPass(PassRegistry&);
 void initializeLoopPassPass(PassRegistry&);
 void initializeLoopPredicationLegacyPassPass(PassRegistry&);
 void initializeLoopRerollLegacyPassPass(PassRegistry &);
diff --git a/llvm/include/llvm/LinkAllPasses.h b/llvm/include/llvm/LinkAllPasses.h
index a7391de8fe22f4..335460f700af8d 100644
--- a/llvm/include/llvm/LinkAllPasses.h
+++ b/llvm/include/llvm/LinkAllPasses.h
@@ -108,7 +108,6 @@ namespace {
       (void) llvm::createLoopSinkPass();
       (void) llvm::createLazyValueInfoPass();
       (void) llvm::createLoopExtractorPass();
-      (void) llvm::createLoopFlattenPass();
       (void) llvm::createLoopPredicationPass();
       (void) llvm::createLoopSimplifyPass();
       (void) llvm::createLoopSimplifyCFGPass();
diff --git a/llvm/include/llvm/Transforms/Scalar.h b/llvm/include/llvm/Transforms/Scalar.h
index 85b19315dcd03a..44d57f21a3f1d2 100644
--- a/llvm/include/llvm/Transforms/Scalar.h
+++ b/llvm/include/llvm/Transforms/Scalar.h
@@ -143,12 +143,6 @@ Pass *createLoopSinkPass();
 //
 Pass *createLoopPredicationPass();
 
-//===----------------------------------------------------------------------===//
-//
-// LoopFlatten - This pass flattens nested loops into a single loop.
-//
-FunctionPass *createLoopFlattenPass();
-
 //===----------------------------------------------------------------------===//
 //
 // LoopStrengthReduce - This pass is strength reduces GEP instructions that use
diff --git a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
index 7d9ce8d35e0b4f..9fc69f528617be 100644
--- a/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFlatten.cpp
@@ -963,60 +963,3 @@ PreservedAnalyses LoopFlattenPass::run(LoopNest &LN, LoopAnalysisManager &LAM,
     PA.preserve<MemorySSAAnalysis>();
   return PA;
 }
-
-namespace {
-class LoopFlattenLegacyPass : public FunctionPass {
-public:
-  static char ID; // Pass ID, replacement for typeid
-  LoopFlattenLegacyPass() : FunctionPass(ID) {
-    initializeLoopFlattenLegacyPassPass(*PassRegistry::getPassRegistry());
-  }
-
-  // Possibly flatten loop L into its child.
-  bool runOnFunction(Function &F) override;
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    getLoopAnalysisUsage(AU);
-    AU.addRequired<TargetTransformInfoWrapperPass>();
-    AU.addPreserved<TargetTransformInfoWrapperPass>();
-    AU.addRequired<AssumptionCacheTracker>();
-    AU.addPreserved<AssumptionCacheTracker>();
-    AU.addPreserved<MemorySSAWrapperPass>();
-  }
-};
-} // namespace
-
-char LoopFlattenLegacyPass::ID = 0;
-INITIALIZE_PASS_BEGIN(LoopFlattenLegacyPass, "loop-flatten", "Flattens loops",
-                      false, false)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_END(LoopFlattenLegacyPass, "loop-flatten", "Flattens loops",
-                    false, false)
-
-FunctionPass *llvm::createLoopFlattenPass() {
-  return new LoopFlattenLegacyPass();
-}
-
-bool LoopFlattenLegacyPass::runOnFunction(Function &F) {
-  ScalarEvolution *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
-  LoopInfo *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
-  auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
-  DominatorTree *DT = DTWP ? &DTWP->getDomTree() : nullptr;
-  auto &TTIP = getAnalysis<TargetTransformInfoWrapperPass>();
-  auto *TTI = &TTIP.getTTI(F);
-  auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
-  auto *MSSA = getAnalysisIfAvailable<MemorySSAWrapperPass>();
-
-  std::optional<MemorySSAUpdater> MSSAU;
-  if (MSSA)
-    MSSAU = MemorySSAUpdater(&MSSA->getMSSA());
-
-  bool Changed = false;
-  for (Loop *L : *LI) {
-    auto LN = LoopNest::getLoopNest(*L, *SE);
-    Changed |=
-        Flatten(*LN, DT, LI, SE, AC, TTI, nullptr, MSSAU ? &*MSSAU : nullptr);
-  }
-  return Changed;
-}
diff --git a/llvm/lib/Transforms/Scalar/Scalar.cpp b/llvm/lib/Transforms/Scalar/Scalar.cpp
index 31b39128dd1c4c..aa4dd61c497492 100644
--- a/llvm/lib/Transforms/Scalar/Scalar.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalar.cpp
@@ -62,7 +62,6 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
   initializeLoopDeletionLegacyPassPass(Registry);
   initializeLoopAccessLegacyAnalysisPass(Registry);
   initializeLoopInstSimplifyLegacyPassPass(Registry);
-  initializeLoopFlattenLegacyPassPass(Registry);
   initializeLoopPredicationLegacyPassPass(Registry);
   initializeLoopRotateLegacyPassPass(Registry);
   initializeLoopStrengthReducePass(Registry);
@@ -175,10 +174,6 @@ void LLVMAddLoopDeletionPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopDeletionPass());
 }
 
-void LLVMAddLoopFlattenPass(LLVMPassManagerRef PM) {
-  unwrap(PM)->add(createLoopFlattenPass());
-}
-
 void LLVMAddLoopIdiomPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopIdiomPass());
 }