Index: llvm/trunk/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp
@@ -4086,8 +4086,8 @@
       V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo);
   ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned);
   ConstantRange CR2 = computeConstantRange(V, UseInstrInfo);
-  // TODO: Use ForSigned to determine preferred range.
-  ConstantRange::PreferredRangeType RangeType = ConstantRange::Smallest;
+  ConstantRange::PreferredRangeType RangeType =
+      ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned;
   return CR1.intersectWith(CR2, RangeType);
 }
 
@@ -4133,12 +4133,10 @@
       ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1)
     return OverflowResult::NeverOverflows;
 
-  KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT);
-  KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT);
-  ConstantRange LHSRange =
-      ConstantRange::fromKnownBits(LHSKnown, /*signed*/ true);
-  ConstantRange RHSRange =
-      ConstantRange::fromKnownBits(RHSKnown, /*signed*/ true);
+  ConstantRange LHSRange = computeConstantRangeIncludingKnownBits(
+      LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
+  ConstantRange RHSRange = computeConstantRangeIncludingKnownBits(
+      RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
   OverflowResult OR =
       mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange));
   if (OR != OverflowResult::MayOverflow)
Index: llvm/trunk/test/Transforms/InstCombine/and2.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/and2.ll
+++ llvm/trunk/test/Transforms/InstCombine/and2.ll
@@ -154,7 +154,7 @@
 ; CHECK-LABEL: @and1_lshr1_is_cmp_eq_0_multiuse(
 ; CHECK-NEXT:    [[SH:%.*]] = lshr i8 1, %x
 ; CHECK-NEXT:    [[AND:%.*]] = and i8 [[SH]], 1
-; CHECK-NEXT:    [[ADD:%.*]] = add nuw i8 [[SH]], [[AND]]
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw i8 [[SH]], [[AND]]
 ; CHECK-NEXT:    ret i8 [[ADD]]
 ;
   %sh = lshr i8 1, %x
Index: llvm/trunk/test/Transforms/InstCombine/icmp-add.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp-add.ll
+++ llvm/trunk/test/Transforms/InstCombine/icmp-add.ll
@@ -407,7 +407,7 @@
 ; CHECK-LABEL: @sum_ugt_op_uses(
 ; CHECK-NEXT:    [[X:%.*]] = sdiv i8 42, [[P1:%.*]]
 ; CHECK-NEXT:    [[Y:%.*]] = sdiv i8 42, [[P2:%.*]]
-; CHECK-NEXT:    [[A:%.*]] = add i8 [[X]], [[Y]]
+; CHECK-NEXT:    [[A:%.*]] = add nsw i8 [[X]], [[Y]]
 ; CHECK-NEXT:    store i8 [[A]], i8* [[P3:%.*]], align 1
 ; CHECK-NEXT:    [[C:%.*]] = icmp ugt i8 [[X]], [[A]]
 ; CHECK-NEXT:    ret i1 [[C]]
Index: llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
+++ llvm/trunk/test/Transforms/InstCombine/minmax-fold.ll
@@ -1423,7 +1423,7 @@
 ; CHECK-LABEL: @PR14613_smin(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 40
 ; CHECK-NEXT:    [[TMP2:%.*]] = select i1 [[TMP1]], i8 [[X]], i8 40
-; CHECK-NEXT:    [[U7:%.*]] = add i8 [[TMP2]], 15
+; CHECK-NEXT:    [[U7:%.*]] = add nsw i8 [[TMP2]], 15
 ; CHECK-NEXT:    ret i8 [[U7]]
 ;
   %u4 = sext i8 %x to i32
Index: llvm/trunk/test/Transforms/InstCombine/sadd-with-overflow.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/sadd-with-overflow.ll
+++ llvm/trunk/test/Transforms/InstCombine/sadd-with-overflow.ll
@@ -19,7 +19,8 @@
 
 define { i32, i1 } @fold_mixed_signs(i32 %x) {
 ; CHECK-LABEL: @fold_mixed_signs(
-; CHECK-NEXT:    [[TMP1:%.*]] = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 [[X:%.*]], i32 6)
+; CHECK-NEXT:    [[B:%.*]] = add nsw i32 [[X:%.*]], 6
+; CHECK-NEXT:    [[TMP1:%.*]] = insertvalue { i32, i1 } { i32 undef, i1 false }, i32 [[B]], 0
 ; CHECK-NEXT:    ret { i32, i1 } [[TMP1]]
 ;
   %a = add nsw i32 %x, 13
Index: llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll
+++ llvm/trunk/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -391,7 +391,7 @@
 define i8 @test_scalar_sadd_srem_no_ov(i8 %a) {
 ; CHECK-LABEL: @test_scalar_sadd_srem_no_ov(
 ; CHECK-NEXT:    [[B:%.*]] = srem i8 [[A:%.*]], 100
-; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[B]], i8 28)
+; CHECK-NEXT:    [[R:%.*]] = add nsw i8 [[B]], 28
 ; CHECK-NEXT:    ret i8 [[R]]
 ;
   %b = srem i8 %a, 100
@@ -414,7 +414,7 @@
 ; CHECK-LABEL: @test_scalar_sadd_srem_and_no_ov(
 ; CHECK-NEXT:    [[AA:%.*]] = srem i8 [[A:%.*]], 100
 ; CHECK-NEXT:    [[BB:%.*]] = and i8 [[B:%.*]], 15
-; CHECK-NEXT:    [[R:%.*]] = call i8 @llvm.sadd.sat.i8(i8 [[AA]], i8 [[BB]])
+; CHECK-NEXT:    [[R:%.*]] = add nsw i8 [[AA]], [[BB]]
 ; CHECK-NEXT:    ret i8 [[R]]
 ;
   %aa = srem i8 %a, 100
Index: llvm/trunk/test/Transforms/InstCombine/sub.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/sub.ll
+++ llvm/trunk/test/Transforms/InstCombine/sub.ll
@@ -1185,7 +1185,7 @@
 ; CHECK-LABEL: @test64(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt i32 [[X:%.*]], 255
 ; CHECK-NEXT:    [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[X]], i32 255
-; CHECK-NEXT:    [[RES:%.*]] = add i32 [[TMP2]], 1
+; CHECK-NEXT:    [[RES:%.*]] = add nsw i32 [[TMP2]], 1
 ; CHECK-NEXT:    ret i32 [[RES]]
 ;
   %1 = xor i32 %x, -1
@@ -1242,7 +1242,7 @@
 ; CHECK-LABEL: @test68(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt <2 x i32> [[X:%.*]], <i32 255, i32 255>
 ; CHECK-NEXT:    [[TMP2:%.*]] = select <2 x i1> [[TMP1]], <2 x i32> [[X]], <2 x i32> <i32 255, i32 255>
-; CHECK-NEXT:    [[RES:%.*]] = add <2 x i32> [[TMP2]], <i32 1, i32 1>
+; CHECK-NEXT:    [[RES:%.*]] = add nsw <2 x i32> [[TMP2]], <i32 1, i32 1>
 ; CHECK-NEXT:    ret <2 x i32> [[RES]]
 ;
   %1 = xor <2 x i32> %x, <i32 -1, i32 -1>