diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2407,7 +2407,8 @@
 /// Given a BB that starts with the specified two-entry PHI node,
 /// see if we can eliminate it.
 static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
-                                const DataLayout &DL) {
+                                const DataLayout &DL,
+                                SmallPtrSetImpl<BasicBlock *> *LoopHeaders) {
   // Ok, this is a two entry PHI node.  Check to see if this is a simple "if
   // statement", which has a very simple dominance structure.  Basically, we
   // are trying to find the condition that is being branched on, which
@@ -2515,6 +2516,36 @@
         return Changed;
       }
   }
+
+  // If we know about loop headers, try to avoid conditionally hoisting too much
+  // into in loops.
+  if (LoopHeaders && LoopHeaders->size() <= 10 &&
+      BudgetRemaining <= int(TwoEntryPHINodeFoldingThreshold *
+                             TargetTransformInfo::TCC_Basic) /
+                             2) {
+    BasicBlock *Pred = DomBlock;
+    while (Pred) {
+      if (LoopHeaders->contains(Pred))
+        return false;
+      auto *NewPred = Pred->getSinglePredecessor();
+      if (!NewPred) {
+        // Unfortunately no DT is available here. Try to peak through some
+        // common patterns.
+        SmallVector<BasicBlock *, 2> Predecessors(pred_begin(Pred),
+                                                  pred_end(Pred));
+        if (Predecessors.size() != 2)
+          break;
+        if (Predecessors[0]->getSinglePredecessor() !=
+            Predecessors[1]->getSinglePredecessor())
+          break;
+        NewPred = Predecessors[0]->getSinglePredecessor();
+      }
+      Pred = NewPred;
+      if (Pred == DomBlock)
+        break;
+    }
+  }
+
   assert(DomBlock && "Failed to find root DomBlock");
 
   LLVM_DEBUG(dbgs() << "FOUND IF CONDITION!  " << *IfCond
@@ -6275,7 +6306,7 @@
     // eliminate it, do so now.
     if (auto *PN = dyn_cast<PHINode>(BB->begin()))
       if (PN->getNumIncomingValues() == 2)
-        Changed |= FoldTwoEntryPHINode(PN, TTI, DL);
+        Changed |= FoldTwoEntryPHINode(PN, TTI, DL, LoopHeaders);
   }
 
   Instruction *Terminator = BB->getTerminator();
diff --git a/llvm/test/Transforms/SimplifyCFG/X86/speculate-cttz-ctlz.ll b/llvm/test/Transforms/SimplifyCFG/X86/speculate-cttz-ctlz.ll
--- a/llvm/test/Transforms/SimplifyCFG/X86/speculate-cttz-ctlz.ll
+++ b/llvm/test/Transforms/SimplifyCFG/X86/speculate-cttz-ctlz.ll
@@ -411,12 +411,16 @@
 ; ALL-NEXT:  entry:
 ; ALL-NEXT:    br label [[LOOP_HEADER:%.*]]
 ; ALL:       loop.header:
-; ALL-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP_HEADER]] ]
+; ALL-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[COND_END:%.*]] ]
 ; ALL-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[X:%.*]], 0
+; ALL-NEXT:    br i1 [[TOBOOL]], label [[COND_END]], label [[COND_TRUE:%.*]]
+; ALL:       cond.true:
 ; ALL-NEXT:    [[XOR:%.*]] = xor i32 [[X]], -1
 ; ALL-NEXT:    [[TMP0:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[XOR]], i1 true)
 ; ALL-NEXT:    [[CAST:%.*]] = trunc i32 [[TMP0]] to i16
-; ALL-NEXT:    [[COND:%.*]] = select i1 [[TOBOOL]], i16 32, i16 [[CAST]]
+; ALL-NEXT:    br label [[COND_END]]
+; ALL:       cond.end:
+; ALL-NEXT:    [[COND:%.*]] = phi i16 [ [[CAST]], [[COND_TRUE]] ], [ 32, [[LOOP_HEADER]] ]
 ; ALL-NEXT:    store i16 [[COND]], i16* [[PTR:%.*]], align 2
 ; ALL-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
 ; ALL-NEXT:    [[EC:%.*]] = icmp eq i32 [[IV]], 100