Index: lib/CodeGen/CodeGenPrepare.cpp
===================================================================
--- lib/CodeGen/CodeGenPrepare.cpp
+++ lib/CodeGen/CodeGenPrepare.cpp
@@ -223,8 +223,14 @@
 
 namespace {
 
+enum ExtType {
+  ZeroExtension,   // Zero extension has been seen.
+  SignExtension,   // Sign extension has been seen.
+  BothExtension    // Both extension have been seen.
+};
+
 using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
-using TypeIsSExt = PointerIntPair<Type *, 1, bool>;
+using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
 using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
 using SExts = SmallVector<Instruction *, 16>;
 using ValueToSExts = DenseMap<Value *, SExts>;
@@ -3277,6 +3283,30 @@
 
 /// Hepler class to perform type promotion.
 class TypePromotionHelper {
+  /// Utility function to add a promoted instruction \p ExtOpnd to
+  /// \p PromotedInsts and record the type of extension we have seen.
+  static void addPromotedInst(InstrToOrigTy &PromotedInsts,
+                              Instruction *ExtOpnd,
+                              bool IsSExt) {
+    ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
+    InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
+    if (It != PromotedInsts.end() && It->second.getInt() != ExtTy)
+      ExtTy = BothExtension;
+    PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
+  }
+
+  /// Utility function to query the original type of instruction \p Opnd
+  /// with a matched extension type.
+  static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
+                                 Instruction *Opnd,
+                                 bool IsSExt) {
+    ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
+    InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
+    if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
+      return It->second.getPointer();
+    return nullptr;
+  }
+
   /// Utility function to check whether or not a sign or zero extension
   /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
   /// either using the operands of \p Inst or promoting \p Inst.
@@ -3465,10 +3495,9 @@
   // I.e., check that trunc just drops extended bits of the same kind of
   // the extension.
   // #1 get the type of the operand and check the kind of the extended bits.
-  const Type *OpndType;
-  InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
-  if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)
-    OpndType = It->second.getPointer();
+  const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
+  if (OpndType)
+    ;
   else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
     OpndType = Opnd->getOperand(0)->getType();
   else
@@ -3596,8 +3625,7 @@
 
   // Remember the original type of the instruction before promotion.
   // This is useful to know that the high bits are sign extended bits.
-  PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(
-      ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));
+  addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
   // Step #1.
   TPT.mutateType(ExtOpnd, Ext->getType());
   // Step #2.
Index: test/Transforms/CodeGenPrepare/X86/pr38125.ll
===================================================================
--- test/Transforms/CodeGenPrepare/X86/pr38125.ll
+++ test/Transforms/CodeGenPrepare/X86/pr38125.ll
@@ -0,0 +1,32 @@
+; RUN: opt < %s -codegenprepare -S -mtriple=x86_64-unknown-unknown    | FileCheck %s
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.13.0"
+
+declare void @bar(i64)
+
+@b = global i16 0, align 2
+
+; CHECK:       %promoted = trunc i32 %or to i16
+; CHECK-NEXT:  %c = sext i16 %promoted to i64
+define i32 @foo() {
+entry:
+  %cmp6 = icmp sgt i32 0, -1
+  br i1 %cmp6, label %t, label %f
+
+f:
+  br label %end
+
+t:
+  br label %end
+
+end:
+  %t3 = phi i16 [ 0, %f ], [ -3, %t ]
+  %t4 = load i16, i16* @b, align 2
+  %conv4 = zext i16 %t4 to i32
+  %or = or i16 %t3, %t4
+  %c = sext i16 %or to i64
+  call void @bar(i64 %c)
+  %t5 = and i16 %or, 5
+  %z = zext i16 %t5 to i32
+  ret i32 %z
+}