Index: lib/Target/SystemZ/SystemZElimCompare.cpp
===================================================================
--- lib/Target/SystemZ/SystemZElimCompare.cpp
+++ lib/Target/SystemZ/SystemZElimCompare.cpp
@@ -320,7 +320,14 @@
   unsigned MIFlags = Desc.TSFlags;
 
   // See which compare-style condition codes are available.
-  unsigned ReusableCCMask = SystemZII::getCompareZeroCCMask(MIFlags);
+  unsigned CCValues = SystemZII::getCCValues(MIFlags);
+  unsigned ReusableCCMask;
+  if (MI.getFlag(MachineInstr::NoSWrap) &&
+      (MIFlags & SystemZII::CCIfNoSignedWrap)) {
+    CCValues &= ~SystemZ::CCMASK_ARITH_OVERFLOW;
+    ReusableCCMask = CCValues;
+  } else
+    ReusableCCMask = SystemZII::getCompareZeroCCMask(MIFlags);
 
   // For unsigned comparisons with zero, only equality makes sense.
   unsigned CompareFlags = Compare.getDesc().TSFlags;
@@ -330,7 +337,6 @@
   if (ReusableCCMask == 0)
     return false;
 
-  unsigned CCValues = SystemZII::getCCValues(MIFlags);
   assert((ReusableCCMask & ~CCValues) == 0 && "Invalid CCValues");
 
   bool MIEquivalentToCmp =
Index: lib/Target/SystemZ/SystemZInstrFormats.td
===================================================================
--- lib/Target/SystemZ/SystemZInstrFormats.td
+++ lib/Target/SystemZ/SystemZInstrFormats.td
@@ -90,6 +90,10 @@
   // in cases where a distinction exists.
   bit IsLogical = 0;
 
+  // True if the (add or sub) instruction sets CC according its CCValues, but
+  // only if the 'nsw' flag is set.
+  bit CCIfNoSignedWrap = 0;
+
   let TSFlags{0}     = SimpleBDXLoad;
   let TSFlags{1}     = SimpleBDXStore;
   let TSFlags{2}     = Has20BitOffset;
@@ -101,6 +105,7 @@
   let TSFlags{18}    = CCMaskFirst;
   let TSFlags{19}    = CCMaskLast;
   let TSFlags{20}    = IsLogical;
+  let TSFlags{21}    = CCIfNoSignedWrap;
 }
 
 //===----------------------------------------------------------------------===//
Index: lib/Target/SystemZ/SystemZInstrInfo.h
===================================================================
--- lib/Target/SystemZ/SystemZInstrInfo.h
+++ lib/Target/SystemZ/SystemZInstrInfo.h
@@ -46,7 +46,8 @@
   CompareZeroCCMaskShift = 14,
   CCMaskFirst            = (1 << 18),
   CCMaskLast             = (1 << 19),
-  IsLogical              = (1 << 20)
+  IsLogical              = (1 << 20),
+  CCIfNoSignedWrap       = (1 << 21)
 };
 
 static inline unsigned getAccessSize(unsigned int Flags) {
Index: lib/Target/SystemZ/SystemZInstrInfo.cpp
===================================================================
--- lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -1036,6 +1036,12 @@
   }
 }
 
+static void transferMIFlag(MachineInstr *OldMI, MachineInstr *NewMI,
+                           MachineInstr::MIFlag Flag) {
+  if (OldMI->getFlag(Flag))
+    NewMI->setFlag(Flag);
+}
+
 MachineInstr *SystemZInstrInfo::convertToThreeAddress(
     MachineFunction::iterator &MFI, MachineInstr &MI, LiveVariables *LV) const {
   MachineBasicBlock *MBB = MI.getParent();
@@ -1141,6 +1147,7 @@
             .addImm(0)
             .addImm(MI.getOperand(2).getImm());
     transferDeadCC(&MI, BuiltMI);
+    transferMIFlag(&MI, BuiltMI, MachineInstr::NoSWrap);
     return BuiltMI;
   }
 
@@ -1291,6 +1298,7 @@
       if (MemDesc.TSFlags & SystemZII::HasIndex)
         MIB.addReg(0);
       transferDeadCC(&MI, MIB);
+      transferMIFlag(&MI, MIB, MachineInstr::NoSWrap);
       return MIB;
     }
   }
Index: lib/Target/SystemZ/SystemZInstrInfo.td
===================================================================
--- lib/Target/SystemZ/SystemZInstrInfo.td
+++ lib/Target/SystemZ/SystemZInstrInfo.td
@@ -915,7 +915,7 @@
 //===----------------------------------------------------------------------===//
 
 // Addition producing a signed overflow flag.
-let Defs = [CC], CCValues = 0xF, CompareZeroCCMask = 0x8 in {
+let Defs = [CC], CCValues = 0xF, CCIfNoSignedWrap = 1 in {
   // Addition of a register.
   let isCommutable = 1 in {
     defm AR : BinaryRRAndK<"ar", 0x1A, 0xB9F8, z_sadd, GR32, GR32>;
@@ -1017,7 +1017,8 @@
 //===----------------------------------------------------------------------===//
 
 // Subtraction producing a signed overflow flag.
-let Defs = [CC], CCValues = 0xF, CompareZeroCCMask = 0x8 in {
+let Defs = [CC], CCValues = 0xF, CompareZeroCCMask = 0x8,
+    CCIfNoSignedWrap = 1 in {
   // Subtraction of a register.
   defm SR : BinaryRRAndK<"sr", 0x1B, 0xB9F9, z_ssub, GR32, GR32>;
   def SGFR : BinaryRRE<"sgfr", 0xB919, null_frag, GR64, GR32>;
Index: test/CodeGen/SystemZ/int-cmp-44.ll
===================================================================
--- test/CodeGen/SystemZ/int-cmp-44.ll
+++ test/CodeGen/SystemZ/int-cmp-44.ll
@@ -6,15 +6,16 @@
 
 declare void @foo()
 
-; Addition provides enough for equality comparisons with zero.  First teest
-; the EQ case.
+; Addition provides enough for comparisons with zero if we know no
+; signed overflow happens, which is when the "nsw" flag is set.
+; First test the EQ case.
 define i32 @f1(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f1:
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: ber %r14
 ; CHECK: br %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -30,10 +31,10 @@
 define i32 @f2(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f2:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: bner %r14
+; CHECK-NEXT: blhr %r14
 ; CHECK: br %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp ne i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -45,14 +46,13 @@
   ret i32 %res
 }
 
-; SLT requires a comparison.
+; ...and again with SLT.
 define i32 @f3(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f3:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: cibl %r2, 0, 0(%r14)
-; CHECK: br %r14
+; CHECK-NEXT: blr %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp slt i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -64,14 +64,13 @@
   ret i32 %res
 }
 
-; ...SLE too.
+; ...and again with SLE.
 define i32 @f4(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f4:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: cible %r2, 0, 0(%r14)
-; CHECK: br %r14
+; CHECK-NEXT: bler %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp sle i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -83,14 +82,13 @@
   ret i32 %res
 }
 
-; ...SGT too.
+; ...and again with SGT.
 define i32 @f5(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f5:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: cibh %r2, 0, 0(%r14)
-; CHECK: br %r14
+; CHECK-NEXT: bhr %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp sgt i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -102,14 +100,13 @@
   ret i32 %res
 }
 
-; ...SGE too.
+; ...and again with SGE.
 define i32 @f6(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f6:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: cibhe %r2, 0, 0(%r14)
-; CHECK: br %r14
+; CHECK-NEXT: bher %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   %cmp = icmp sge i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -121,7 +118,8 @@
   ret i32 %res
 }
 
-; Subtraction also provides enough for equality comparisons with zero.
+; Subtraction provides in addition also enough for equality comparisons with
+; zero even without "nsw".
 define i32 @f7(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f7:
 ; CHECK: s %r2, 0(%r4)
@@ -141,15 +139,14 @@
   ret i32 %res
 }
 
-; ...but not for ordered comparisons.
+; ...and again with SLT.
 define i32 @f8(i32 %a, i32 %b, i32 *%dest) {
 ; CHECK-LABEL: f8:
 ; CHECK: s %r2, 0(%r4)
-; CHECK-NEXT: cibl %r2, 0, 0(%r14)
-; CHECK: br %r14
+; CHECK-NEXT: blr %r14
 entry:
   %cur = load i32, i32 *%dest
-  %res = sub i32 %a, %cur
+  %res = sub nsw i32 %a, %cur
   %cmp = icmp slt i32 %res, 0
   br i1 %cmp, label %exit, label %store
 
@@ -445,10 +442,10 @@
 ; CHECK-LABEL: f23:
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: st %r2, 0(%r4)
-; CHECK-NEXT: bner %r14
+; CHECK-NEXT: blhr %r14
 ; CHECK: br %r14
 entry:
-  %res = add i32 %a, 1000000
+  %res = add nsw i32 %a, 1000000
   store i32 %res, i32 *%dest1
   %cmp = icmp ne i32 %res, 0
   br i1 %cmp, label %exit, label %store
@@ -491,10 +488,10 @@
 ; CHECK-NEXT: #APP
 ; CHECK-NEXT: blah
 ; CHECK-NEXT: #NO_APP
-; CHECK-NEXT: bner %r14
+; CHECK-NEXT: blhr %r14
 ; CHECK: br %r14
 entry:
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   call void asm sideeffect "blah", "r"(i32 %add)
   %cmp = icmp ne i32 %add, 0
   br i1 %cmp, label %exit, label %store
@@ -540,7 +537,7 @@
 ; CHECK-NEXT: cibe %r2, 0, 0(%r14)
 ; CHECK: br %r14
 entry:
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %sub = sub i32 %b, %add
   store i32 %sub, i32 *%dest1
   %cmp = icmp eq i32 %add, 0
Index: test/CodeGen/SystemZ/int-cmp-45.ll
===================================================================
--- test/CodeGen/SystemZ/int-cmp-45.ll
+++ test/CodeGen/SystemZ/int-cmp-45.ll
@@ -3,14 +3,15 @@
 ;
 ; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z196 -no-integrated-as | FileCheck %s
 
-; Addition provides enough for equality comparisons with zero.  First teest
-; the EQ case with LOC.
+; Addition provides enough for comparisons with zero if we know no
+; signed overflow happens, which is when the "nsw" flag is set.
+; First test the EQ case with LOC.
 define i32 @f1(i32 %a, i32 %b, i32 *%cptr) {
 ; CHECK-LABEL: f1:
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: loce %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %add, 0
   %c = load i32, i32 *%cptr
   %arg = select i1 %cmp, i32 %c, i32 %b
@@ -24,7 +25,7 @@
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: stoce %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %add, 0
   %c = load i32, i32 *%cptr
   %newval = select i1 %cmp, i32 %b, i32 %c
@@ -36,9 +37,9 @@
 define i32 @f3(i32 %a, i32 %b, i32 %c) {
 ; CHECK-LABEL: f3:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: locrne %r3, %r4
+; CHECK-NEXT: locrlh %r3, %r4
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %add, 0
   %arg = select i1 %cmp, i32 %b, i32 %c
   call void asm sideeffect "blah $0", "{r3}"(i32 %arg)
@@ -49,9 +50,9 @@
 define i32 @f4(i32 %a, i32 %b, i32 *%cptr) {
 ; CHECK-LABEL: f4:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: locne %r3, 0(%r4)
+; CHECK-NEXT: loclh %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %add, 0
   %c = load i32, i32 *%cptr
   %arg = select i1 %cmp, i32 %b, i32 %c
@@ -63,9 +64,9 @@
 define i32 @f5(i32 %a, i32 %b, i32 *%cptr) {
 ; CHECK-LABEL: f5:
 ; CHECK: afi %r2, 1000000
-; CHECK-NEXT: stocne %r3, 0(%r4)
+; CHECK-NEXT: stoclh %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp eq i32 %add, 0
   %c = load i32, i32 *%cptr
   %newval = select i1 %cmp, i32 %c, i32 %b
@@ -79,7 +80,7 @@
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: locre %r3, %r4
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp ne i32 %add, 0
   %arg = select i1 %cmp, i32 %b, i32 %c
   call void asm sideeffect "blah $0", "{r3}"(i32 %arg)
@@ -92,7 +93,7 @@
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: loce %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp ne i32 %add, 0
   %c = load i32, i32 *%cptr
   %arg = select i1 %cmp, i32 %b, i32 %c
@@ -106,7 +107,7 @@
 ; CHECK: afi %r2, 1000000
 ; CHECK-NEXT: stoce %r3, 0(%r4)
 ; CHECK: br %r14
-  %add = add i32 %a, 1000000
+  %add = add nsw i32 %a, 1000000
   %cmp = icmp ne i32 %add, 0
   %c = load i32, i32 *%cptr
   %newval = select i1 %cmp, i32 %c, i32 %b
Index: test/CodeGen/SystemZ/int-cmp-56.ll
===================================================================
--- /dev/null
+++ test/CodeGen/SystemZ/int-cmp-56.ll
@@ -0,0 +1,160 @@
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z14 | FileCheck %s
+;
+; Check that signed comparisons against 0 are only eliminated if
+; the "nsw" flag is present on the defining add instruction.
+
+define i32 @fun0(i32 %arg, i32 %arg2) {
+; CHECK-LABEL: fun0:
+; CHECK: jle .LBB0_2{{$}}
+; CHECK: je .LBB0_4{{$}}
+
+bb:
+  %tmp2 = add nsw i32 %arg, -1
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = add nsw i32 %arg, %arg2
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
+
+; No "nsw" flag
+define i32 @fun1(i32 %arg, i32 %arg2) {
+; CHECK-LABEL: fun1:
+; CHECK: cijle
+; CHECK: cije
+
+bb:
+  %tmp2 = add i32 %arg, -1
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = add i32 %arg, %arg2
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
+
+; "nuw" flag
+define i32 @fun2(i32 %arg, i32 %arg2) {
+; CHECK-LABEL: fun2:
+; CHECK: cijle
+; CHECK: cije
+
+bb:
+  %tmp2 = add nuw i32 %arg, -1
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = add nuw i32 %arg, %arg2
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
+
+; Subtraction does not produce the value of zero in case of overflow, so
+; "nsw" is not needed for the equality check against zero.
+define i32 @fun3(i32 %arg, i32 %arg2, i32 %arg3) {
+; CHECK-LABEL: fun3:
+; CHECK: jle .LBB3_2{{$}}
+; CHECK: je .LBB3_4{{$}}
+
+bb:
+  %tmp2 = sub nsw i32 %arg, %arg2
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = sub nsw i32 %arg, %arg3
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
+
+; No "nsw" flag
+define i32 @fun4(i32 %arg, i32 %arg2, i32 %arg3) {
+; CHECK-LABEL: fun4:
+; CHECK: cijle
+; CHECK: je .LBB4_4{{$}}
+
+bb:
+  %tmp2 = sub i32 %arg, %arg2
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = sub i32 %arg, %arg3
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
+
+; "nuw" flag
+define i32 @fun5(i32 %arg, i32 %arg2, i32 %arg3) {
+; CHECK-LABEL: fun5:
+; CHECK: cijle
+; CHECK: je .LBB5_4{{$}}
+
+bb:
+  %tmp2 = sub nuw i32 %arg, %arg2
+  %tmp3 = icmp sgt i32 %tmp2, 0
+  br i1 %tmp3, label %bb3, label %bb1
+
+bb1:
+  %tmp4 = sub nuw i32 %arg, %arg3
+  %tmp5 = icmp eq i32 %tmp4, 0
+  br i1 %tmp5, label %bb4, label %bb2
+
+bb2:
+  ret i32 0
+
+bb3:
+  ret i32 1
+
+bb4:
+  ret i32 2
+}
Index: test/CodeGen/SystemZ/loop-01.ll
===================================================================
--- test/CodeGen/SystemZ/loop-01.ll
+++ test/CodeGen/SystemZ/loop-01.ll
@@ -94,7 +94,7 @@
 ; CHECK: aghi [[REG:%r[0-5]]], -1
 ; CHECK: lr [[REG2:%r[0-5]]], [[REG]]
 ; CHECK: stg [[REG2]],
-; CHECK: jne {{\..*}}
+; CHECK: cgijlh [[REG]], 0, {{\..*}}
 ; CHECK: br %r14
 entry:
   br label %loop