Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -912,6 +912,35 @@
   return nullptr;
 }
 
+/// If one of the operands is a sext/zext from i1 and the other is a constant,
+/// we may be able to create an i1 select which can be further folded to
+/// logical ops.
+static Instruction *foldSelectExtConst(InstCombiner::BuilderTy &Builder,
+                                       SelectInst &SI, Instruction *EI,
+                                       const APInt &C, bool isExtTrueVal,
+                                       bool isSigned) {
+  Value *SmallVal = EI->getOperand(0);
+  Type *SmallType = SmallVal->getType();
+
+  if (!SmallType->getScalarType()->isIntegerTy(1))
+    return nullptr;
+
+  if (C != 0 && (isSigned || C != 1) &&
+      (!isSigned || !C.isAllOnesValue()))
+    return nullptr;
+
+  Value *SmallConst = ConstantInt::get(SmallType, C.trunc(1));
+  Value *TrueVal = isExtTrueVal ? SmallVal : SmallConst;
+  Value *FalseVal = isExtTrueVal ? SmallConst : SmallVal;
+  Value *Select = Builder.CreateSelect(SI.getOperand(0), TrueVal, FalseVal,
+                                       "fold." + SI.getName());
+
+  if (isSigned)
+    return new SExtInst(Select, SI.getType());
+
+  return new ZExtInst(Select, SI.getType());
+}
+
 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
   Value *CondVal = SI.getCondition();
   Value *TrueVal = SI.getTrueValue();
@@ -1098,6 +1127,31 @@
     if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
       return IV;
 
+  // (select C, (sext X), const) -> (sext (select C, X, const')) and
+  // variations thereof when extending from i1, as that allows further folding
+  // into logic ops. When the sext is from a larger type, we prefer to have it
+  // as an operand.
+  if (TI &&
+      (TI->getOpcode() == Instruction::ZExt || TI->getOpcode() == Instruction::SExt)) {
+    bool IsSExt = TI->getOpcode() == Instruction::SExt;
+    const APInt *C;
+    if (match(FalseVal, m_APInt(C))) {
+      if (Instruction *IV =
+              foldSelectExtConst(*Builder, SI, TI, *C, true, IsSExt))
+        return IV;
+    }
+  }
+  if (FI &&
+      (FI->getOpcode() == Instruction::ZExt || FI->getOpcode() == Instruction::SExt)) {
+    bool IsSExt = FI->getOpcode() == Instruction::SExt;
+    const APInt *C;
+    if (match(TrueVal, m_APInt(C))) {
+      if (Instruction *IV =
+              foldSelectExtConst(*Builder, SI, FI, *C, false, IsSExt))
+          return IV;
+    }
+  }
+
   // See if we can fold the select into one of our operands.
   if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
     if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
Index: lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- lib/Transforms/InstCombine/InstructionCombining.cpp
+++ lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -790,7 +790,7 @@
 
   if (isa<Constant>(TV) || isa<Constant>(FV)) {
     // Bool selects with constant operands can be folded to logical ops.
-    if (SI->getType()->isIntegerTy(1)) return nullptr;
+    if (SI->getType()->getScalarType()->isIntegerTy(1)) return nullptr;
 
     // If it's a bitcast involving vectors, make sure it has the same number of
     // elements on both sides.
Index: test/Transforms/InstCombine/select-bitext.ll
===================================================================
--- test/Transforms/InstCombine/select-bitext.ll
+++ test/Transforms/InstCombine/select-bitext.ll
@@ -3,8 +3,8 @@
 
 define i32 @test_sext1(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_sext1(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 0
+; CHECK-NEXT:    [[FOLD_R:%.*]] = and i1 %ccb, %cca
+; CHECK-NEXT:    [[R:%.*]] = sext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = sext i1 %cca to i32
@@ -14,8 +14,8 @@
 
 define i32 @test_sext2(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_sext2(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 -1, i32 [[CCAX]]
+; CHECK-NEXT:    [[FOLD_R:%.*]] = or i1 %ccb, %cca
+; CHECK-NEXT:    [[R:%.*]] = sext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = sext i1 %cca to i32
@@ -25,8 +25,9 @@
 
 define i32 @test_sext3(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_sext3(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 0, i32 [[CCAX]]
+; CHECK-NEXT:    [[NOT_CCB:%.*]] = xor i1 %ccb, true
+; CHECK-NEXT:    [[FOLD_R:%.*]] = and i1 [[NOT_CCB]], %cca
+; CHECK-NEXT:    [[R:%.*]] = sext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = sext i1 %cca to i32
@@ -36,8 +37,9 @@
 
 define i32 @test_sext4(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_sext4(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 -1
+; CHECK-NEXT:    [[NOT_CCB:%.*]] = xor i1 %ccb, true
+; CHECK-NEXT:    [[FOLD_R:%.*]] = or i1 [[NOT_CCB]], %cca
+; CHECK-NEXT:    [[R:%.*]] = sext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = sext i1 %cca to i32
@@ -47,8 +49,8 @@
 
 define i32 @test_zext1(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_zext1(
-; CHECK-NEXT:    [[CCAX:%.*]] = zext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 0
+; CHECK-NEXT:    [[FOLD_R:%.*]] = and i1 %ccb, %cca
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = zext i1 %cca to i32
@@ -58,8 +60,8 @@
 
 define i32 @test_zext2(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_zext2(
-; CHECK-NEXT:    [[CCAX:%.*]] = zext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 1, i32 [[CCAX]]
+; CHECK-NEXT:    [[FOLD_R:%.*]] = or i1 %ccb, %cca
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = zext i1 %cca to i32
@@ -69,8 +71,9 @@
 
 define i32 @test_zext3(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_zext3(
-; CHECK-NEXT:    [[CCAX:%.*]] = zext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 0, i32 [[CCAX]]
+; CHECK-NEXT:    [[NOT_CCB:%.*]] = xor i1 %ccb, true
+; CHECK-NEXT:    [[FOLD_R:%.*]] = and i1 [[NOT_CCB]], %cca
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = zext i1 %cca to i32
@@ -80,8 +83,9 @@
 
 define i32 @test_zext4(i1 %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_zext4(
-; CHECK-NEXT:    [[CCAX:%.*]] = zext i1 %cca to i32
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 1
+; CHECK-NEXT:    [[NOT_CCB:%.*]] = xor i1 %ccb, true
+; CHECK-NEXT:    [[FOLD_R:%.*]] = or i1 [[NOT_CCB]], %cca
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[FOLD_R]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %ccax = zext i1 %cca to i32
@@ -153,8 +157,8 @@
 
 define <2 x i32> @test_vectors1(<2 x i1> %cca, <2 x i1> %ccb) {
 ; CHECK-LABEL: @test_vectors1(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext <2 x i1> %cca to <2 x i32>
-; CHECK-NEXT:    [[R:%.*]] = select <2 x i1> %ccb, <2 x i32> [[CCAX]], <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[FOLD_R:%.*]] = and <2 x i1> %ccb, %cca
+; CHECK-NEXT:    [[R:%.*]] = sext <2 x i1> [[FOLD_R]] to <2 x i32>
 ; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %ccax = sext <2 x i1> %cca to <2 x i32>
@@ -164,8 +168,8 @@
 
 define <2 x i32> @test_vectors2(<2 x i1> %cca, i1 %ccb) {
 ; CHECK-LABEL: @test_vectors2(
-; CHECK-NEXT:    [[CCAX:%.*]] = sext <2 x i1> %cca to <2 x i32>
-; CHECK-NEXT:    [[R:%.*]] = select i1 %ccb, <2 x i32> [[CCAX]], <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[FOLD_R:%.*]] = select i1 %ccb, <2 x i1> %cca, <2 x i1> zeroinitializer
+; CHECK-NEXT:    [[R:%.*]] = sext <2 x i1> [[FOLD_R]] to <2 x i32>
 ; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %ccax = sext <2 x i1> %cca to <2 x i32>
Index: test/Transforms/InstCombine/vector-casts.ll
===================================================================
--- test/Transforms/InstCombine/vector-casts.ll
+++ test/Transforms/InstCombine/vector-casts.ll
@@ -63,9 +63,8 @@
 	ret <2 x i64> %conv
         
 ; CHECK-LABEL: @test5(
-; CHECK:   sext <4 x i1> %cmp to <4 x i32>	
-; The sext-and pair is canonicalized to a select.
-; CHECK:   select <4 x i1> %cmp4, <4 x i32>	%sext, <4 x i32> zeroinitializer
+; CHECK:   %fold.and = and <4 x i1> %cmp4, %cmp
+; CHECK:   sext <4 x i1> %fold.and to <4 x i32>
 }