Index: llvm/lib/Transforms/Scalar/JumpThreading.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -207,7 +207,8 @@
 //  In other words, if we know P(cond == true) is unlikely, we know
 //  that P(t == true) is also unlikely.
 //
-static void updatePredecessorProfileMetadata(PHINode *PN, BasicBlock *BB) {
+static void updatePredecessorProfileMetadata(PHINode *PN, BasicBlock *BB,
+                                             DominatorTree &DT) {
   BranchInst *CondBr = dyn_cast<BranchInst>(BB->getTerminator());
   if (!CondBr)
     return;
@@ -220,20 +221,23 @@
   // Returns the outgoing edge of the dominating predecessor block
   // that leads to the PhiNode's incoming block:
   auto GetPredOutEdge =
-      [](BasicBlock *IncomingBB,
-         BasicBlock *PhiBB) -> std::pair<BasicBlock *, BasicBlock *> {
+      [&](BasicBlock *IncomingBB,
+          BasicBlock *PhiBB) -> std::pair<BasicBlock *, BasicBlock *> {
     auto *PredBB = IncomingBB;
     auto *SuccBB = PhiBB;
     while (true) {
+      // Stop searching when PredBB is unreachable. It is waste of time
+      // to propagate prof meta data to unreachable code and may also
+      // cause infinite loop.
+      if (!DT.isReachableFromEntry(PredBB))
+        return {nullptr, nullptr};
+
       BranchInst *PredBr = dyn_cast<BranchInst>(PredBB->getTerminator());
       if (PredBr && PredBr->isConditional())
         return {PredBB, SuccBB};
       auto *SinglePredBB = PredBB->getSinglePredecessor();
       if (!SinglePredBB)
         return {nullptr, nullptr};
-      // For unreachable one block loop, stop searching.
-      if (PredBB == SinglePredBB)
-        return {PredBB, SuccBB};
       SuccBB = PredBB;
       PredBB = SinglePredBB;
     }
@@ -1207,7 +1211,7 @@
   // Before threading, try to propagate profile data backwards:
   if (PHINode *PN = dyn_cast<PHINode>(CondInst))
     if (PN->getParent() == BB && isa<BranchInst>(BB->getTerminator()))
-      updatePredecessorProfileMetadata(PN, BB);
+      updatePredecessorProfileMetadata(PN, BB, DTU->getDomTree());
 
   // Handle a variety of cases where we are branching on something derived from
   // a PHI node in the current block.  If we can prove that any predecessors
Index: llvm/test/Transforms/JumpThreading/unreachable-single-bb-loop.ll
===================================================================
--- llvm/test/Transforms/JumpThreading/unreachable-single-bb-loop.ll
+++ llvm/test/Transforms/JumpThreading/unreachable-single-bb-loop.ll
@@ -1,11 +1,11 @@
 ; RUN: opt -jump-threading -S < %s | FileCheck %s
 ; RUN: opt -passes=jump-threading -S < %s | FileCheck %s
-; Check the unreachable single bb loop won't cause infinite loop
+; Check the unreachable loop won't cause infinite loop
 ; in jump-threading when it tries to update the predecessors'
 ; profile metadata from a phi node.
 
-define void @test() {
-; CHECK-LABEL: @test()
+define void @unreachable_single_bb_loop() {
+; CHECK-LABEL: @unreachable_single_bb_loop()
 bb:
   %tmp = call i32 @a()
   %tmp1 = icmp eq i32 %tmp, 1
@@ -30,6 +30,34 @@
   ret void
 }
 
+define void @unreachable_multi_bbs_loop() {
+; CHECK-LABEL: @unreachable_multi_bbs_loop()
+bb:
+  %tmp = call i32 @a()
+  %tmp1 = icmp eq i32 %tmp, 1
+  br i1 %tmp1, label %bb5, label %bb8
+
+; unreachable two bbs loop.
+bb3:                                              ; preds = %bb2
+  br label %bb2
+
+bb2:                                              ; preds = %bb3
+  %tmp4 = icmp ne i32 %tmp, 1
+  switch i1 %tmp4, label %bb3 [
+    i1 0, label %bb5
+    i1 1, label %bb8
+  ]
+
+bb5:                                              ; preds = %bb2, %bb
+  %tmp6 = phi i1 [ %tmp1, %bb ], [ false, %bb2 ]
+  br i1 %tmp6, label %bb8, label %bb7, !prof !0
+
+bb7:                                              ; preds = %bb5
+  br label %bb8
+
+bb8:                                              ; preds = %bb8, %bb7, %bb5, %bb2
+  ret void
+}
 declare i32 @a()
 
 !0 = !{!"branch_weights", i32 2146410443, i32 1073205}