Index: lib/Analysis/InstructionSimplify.cpp
===================================================================
--- lib/Analysis/InstructionSimplify.cpp
+++ lib/Analysis/InstructionSimplify.cpp
@@ -69,6 +69,34 @@
 static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &,
                               unsigned);
 
+/// We want to turn:
+///   (select (icmp sgt x, -1), lshr (X, Y), ashr (X, Y))
+///   (select (icmp slt x, 1), ashr (X, Y), lshr (X, Y))
+/// into:
+///   ashr (X, Y)
+/// only if both of the shifts either have or have no exact
+static Value *foldSelectICmpLshrAshr(const ICmpInst::Predicate Pred,
+                                     const Value *CmpLHS, const Value *CmpRHS,
+                                     Value *TrueVal, Value *FalseVal) {
+  Value *X, *Y;
+  if ((Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) ||
+      (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_One()))) {
+    if (Pred == ICmpInst::ICMP_SLT)
+      std::swap(TrueVal, FalseVal);
+
+    if (match(TrueVal, m_LShr(m_Value(X), m_Value(Y))) &&
+        match(FalseVal, m_AShr(m_Specific(X), m_Specific(Y))) &&
+        match(CmpLHS, m_Specific(X))) {
+      if (cast<BinaryOperator>(TrueVal)->isExact() !=
+          cast<BinaryOperator>(FalseVal)->isExact())
+        cast<BinaryOperator>(FalseVal)->setIsExact(false);
+      return FalseVal;
+    }
+  }
+
+  return nullptr;
+}
+
 static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
                                      Value *FalseVal) {
   BinaryOperator::BinaryOps BinOpCode;
@@ -3761,6 +3789,10 @@
       return TrueVal;
   }
 
+  if (Value *V =
+          foldSelectICmpLshrAshr(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal))
+    return V;
+
   return nullptr;
 }
 
Index: test/Transforms/InstSimplify/ashr-lshr.ll
===================================================================
--- test/Transforms/InstSimplify/ashr-lshr.ll
+++ test/Transforms/InstSimplify/ashr-lshr.ll
@@ -3,11 +3,8 @@
 
 define i32 @ashr_lshr(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, %y
@@ -18,11 +15,8 @@
 
 define i32 @ashr_lshr_exact(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[L:%.*]] = lshr exact i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr exact i32 %x, %y
@@ -33,11 +27,8 @@
 
 define i32 @ashr_lshr2(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, %y
@@ -48,11 +39,8 @@
 
 define <2 x i32> @ashr_lshr_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 -1, i32 -1>
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 -1, i32 -1>
   %l = lshr <2 x i32> %x, %y
@@ -63,11 +51,8 @@
 
 define <2 x i32> @ashr_lshr_vec2(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_vec2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i32> [[X:%.*]], <i32 undef, i32 -1>
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[L]], <2 x i32> [[R]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %cmp = icmp sgt <2 x i32> %x, <i32 undef, i32 -1>
   %l = lshr <2 x i32> %x, %y
@@ -78,11 +63,8 @@
 
 define <2 x i32> @ashr_lshr_vec3(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_vec3(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 1, i32 undef>
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[R]], <2 x i32> [[L]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %cmp = icmp slt <2 x i32> %x, <i32 1, i32 undef>
   %l = lshr <2 x i32> %x, %y
@@ -93,11 +75,8 @@
 
 define i32 @ashr_lshr_inv(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_inv(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 1
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[R]], i32 [[L]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp slt i32 %x, 1
   %l = lshr i32 %x, %y
@@ -108,11 +87,8 @@
 
 define <2 x i32> @ashr_lshr_inv_vec(<2 x i32> %x, <2 x i32> %y) {
 ; CHECK-LABEL: @ashr_lshr_inv_vec(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 1, i32 1>
-; CHECK-NEXT:    [[L:%.*]] = lshr <2 x i32> [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select <2 x i1> [[CMP]], <2 x i32> [[R]], <2 x i32> [[L]]
-; CHECK-NEXT:    ret <2 x i32> [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr <2 x i32> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %cmp = icmp slt <2 x i32> %x, <i32 1, i32 1>
   %l = lshr <2 x i32> %x, %y
@@ -123,11 +99,8 @@
 
 define i32 @ashr_lshr_exact_mismatch(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact_mismatch(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[L:%.*]] = lshr i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr exact i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr i32 %x, %y
@@ -138,11 +111,8 @@
 
 define i32 @ashr_lshr_exact_mismatch2(i32 %x, i32 %y) {
 ; CHECK-LABEL: @ashr_lshr_exact_mismatch2(
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[L:%.*]] = lshr exact i32 [[X]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X]], [[Y]]
-; CHECK-NEXT:    [[RET:%.*]] = select i1 [[CMP]], i32 [[L]], i32 [[R]]
-; CHECK-NEXT:    ret i32 [[RET]]
+; CHECK-NEXT:    [[R:%.*]] = ashr i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[R]]
 ;
   %cmp = icmp sgt i32 %x, -1
   %l = lshr exact i32 %x, %y