diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cppindex a75f29000ca18..30e62367d32f1 100644--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp@@ -7493,7 +7493,7 @@ bool SimplifyCFGOpt::simplifyDuplicateSwitchArms(SwitchInst *SI,   SmallPtrSet<PHINode *, 8> Phis;   SmallPtrSet<BasicBlock *, 8> Seen;   DenseMap<PHINode *, SmallDenseMap<BasicBlock *, Value *, 8>> PhiPredIVs;-  DenseMap<BasicBlock *, SmallVector<unsigned, 4>> BBToSuccessorIndexes;+  DenseMap<BasicBlock *, SmallVector<unsigned, 32>> BBToSuccessorIndexes;   SmallVector<SwitchSuccWrapper> Cases;   Cases.reserve(SI->getNumSuccessors());@@ -7505,12 +7505,6 @@ bool SimplifyCFGOpt::simplifyDuplicateSwitchArms(SwitchInst *SI,     if (BB->size() != 1)       continue;-    // FIXME: This case needs some extra care because the terminators other than-    // SI need to be updated. For now, consider only backedges to the SI.-    if (BB->hasNPredecessorsOrMore(4) ||-        BB->getUniquePredecessor() != SI->getParent())-      continue;-     // FIXME: Relax that the terminator is a BranchInst by checking for equality     // on other kinds of terminators. We decide to only support unconditional     // branches for now for compile time reasons.@@ -7518,14 +7512,22 @@ bool SimplifyCFGOpt::simplifyDuplicateSwitchArms(SwitchInst *SI,     if (!BI || BI->isConditional())       continue;-    if (Seen.insert(BB).second) {-      // Keep track of which PHIs we need as keys in PhiPredIVs below.-      for (BasicBlock *Succ : BI->successors())-        Phis.insert_range(llvm::make_pointer_range(Succ->phis()));-      // Add the successor only if not previously visited.-      Cases.emplace_back(SwitchSuccWrapper{BB, &PhiPredIVs});+    if (!Seen.insert(BB).second) {+      BBToSuccessorIndexes[BB].emplace_back(I);+      continue;     }+    // FIXME: This case needs some extra care because the terminators other than+    // SI need to be updated. For now, consider only backedges to the SI.+    if (BB->getUniquePredecessor() != SI->getParent())+      continue;++    // Keep track of which PHIs we need as keys in PhiPredIVs below.+    for (BasicBlock *Succ : BI->successors())+      Phis.insert_range(llvm::make_pointer_range(Succ->phis()));++    // Add the successor only if not previously visited.+    Cases.emplace_back(SwitchSuccWrapper{BB, &PhiPredIVs});     BBToSuccessorIndexes[BB].emplace_back(I);   }diff --git a/llvm/test/Transforms/SimplifyCFG/switch-dup-bbs.ll b/llvm/test/Transforms/SimplifyCFG/switch-dup-bbs.llindex 32581bbf8f141..d2d917de11897 100644--- a/llvm/test/Transforms/SimplifyCFG/switch-dup-bbs.ll+++ b/llvm/test/Transforms/SimplifyCFG/switch-dup-bbs.ll@@ -199,3 +199,44 @@ exit:   %ret = phi i64 [ 0, %default ], [ 0, %bb1 ], [ 1, %entry ], [ 1, %bb2 ]   ret i64 %ret }++define i32 @switch_dup_unbounded_predecessors(i32 %val) {+; SIMPLIFY-CFG-LABEL: define i32 @switch_dup_unbounded_predecessors(+; SIMPLIFY-CFG-SAME: i32 [[VAL:%.*]]) {+; SIMPLIFY-CFG-NEXT:  [[ENTRY:.*]]:+; SIMPLIFY-CFG-NEXT:    switch i32 [[VAL]], label %[[EXIT:.*]] [+; SIMPLIFY-CFG-NEXT:      i32 99, label %[[BB1:.*]]+; SIMPLIFY-CFG-NEXT:      i32 115, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:      i32 102, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:      i32 70, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:      i32 101, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:      i32 69, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:      i32 103, label %[[BB1]]+; SIMPLIFY-CFG-NEXT:    ]+; SIMPLIFY-CFG:       [[BB1]]:+; SIMPLIFY-CFG-NEXT:    br label %[[EXIT]]+; SIMPLIFY-CFG:       [[EXIT]]:+; SIMPLIFY-CFG-NEXT:    [[PHI:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ 1, %[[BB1]] ]+; SIMPLIFY-CFG-NEXT:    ret i32 [[PHI]]+;+entry:+  switch i32 %val, label %exit [+  i32 99, label %bb1+  i32 115, label %bb1+  i32 102, label %bb2+  i32 70, label %bb2+  i32 101, label %bb2+  i32 69, label %bb2+  i32 103, label %bb2+  ]++bb1:+  br label %exit++bb2:+  br label %exit++exit:+  %phi = phi i32 [ 0, %entry ], [ 1, %bb1 ], [ 1, %bb2 ]+  ret i32 %phi+}diff --git a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.llindex 4136f33983a2b..8f2ae2d054f1e 100644--- a/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll+++ b/llvm/test/Transforms/SimplifyCFG/switch-range-to-icmp.ll@@ -149,7 +149,7 @@ unreach2:  define void @pr53208_single_reachable_dest(i8 %sw, ptr %p0) { ; CHECK-LABEL: @pr53208_single_reachable_dest(-; CHECK-NEXT:  group2:+; CHECK-NEXT:  exit: ; CHECK-NEXT:    call void @bar(ptr [[P0:%.*]]) ; CHECK-NEXT:    ret void ;