Index: lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
===================================================================
--- lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -29,13 +29,6 @@
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
-// Option to allow disabling arithmetic relaxation to workaround PR9807, which
-// is useful when running bitwise comparison experiments on Darwin. We should be
-// able to remove this once PR9807 is resolved.
-static cl::opt<bool>
-MCDisableArithRelaxation("mc-x86-disable-arith-relaxation",
-         cl::desc("Disable relaxation of arithmetic instruction for X86"));
-
 static unsigned getFixupKindLog2Size(unsigned Kind) {
   switch (Kind) {
   default:
@@ -231,6 +224,12 @@
   }
 }
 
+static bool isOperandRelaxable(const MCInst &Inst, unsigned OpNum) {
+  // For the current set of relaxable instructions, the relaxable operand is
+  // always the last operand.
+  return OpNum == Inst.getNumOperands() - 1;
+}
+
 static unsigned getRelaxedOpcode(unsigned Op) {
   unsigned R = getRelaxedOpcodeArith(Op);
   if (R != Op)
@@ -243,9 +242,6 @@
   if (getRelaxedOpcodeBranch(Inst.getOpcode()) != Inst.getOpcode())
     return true;
 
-  if (MCDisableArithRelaxation)
-    return false;
-
   // Check if this instruction is ever relaxable.
   if (getRelaxedOpcodeArith(Inst.getOpcode()) == Inst.getOpcode())
     return false;
@@ -256,7 +252,7 @@
   bool hasRIP = false;
   for (unsigned i = 0; i < Inst.getNumOperands(); ++i) {
     const MCOperand &Op = Inst.getOperand(i);
-    if (Op.isExpr())
+    if (Op.isExpr() && isOperandRelaxable(Inst, i))
       hasExp = true;
 
     if (Op.isReg() && Op.getReg() == X86::RIP)
Index: test/MC/ELF/relax-arith2.s
===================================================================
--- test/MC/ELF/relax-arith2.s
+++ test/MC/ELF/relax-arith2.s
@@ -0,0 +1,104 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -s -sd | FileCheck  %s
+
+// Test that we avoid relaxing these instructions and instead generate versions
+// that use 8-bit immediate values.
+
+bar:
+// CHECK:      Name: imul
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 666BDB80 666B1C25 00000000 7F6BDB00
+// CHECK-NEXT:   0010: 6B1C2500 00000001 486BDBFF 486B1C25
+// CHECK-NEXT:   0020: 00000000 2A
+// CHECK-NEXT: )
+        .section imul
+        imul $-128, %bx,  %bx
+        imul $127, bar,  %bx
+        imul $0, %ebx, %ebx
+        imul $1, bar,  %ebx
+        imul $-1, %rbx, %rbx
+        imul $42, bar,  %rbx
+
+
+// CHECK:      Name: and
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 6683E37F 66832425 00000000 0083E301
+// CHECK-NEXT:   0010: 83242500 000000FF 4883E32A 48832425
+// CHECK-NEXT:   0020: 00000000 80
+// CHECK-NEXT: )
+        .section and
+        and  $127, %bx
+        andw $0, bar
+        and  $1, %ebx
+        andl $-1, bar
+        and  $42, %rbx
+        andq $-128, bar
+
+// CHECK:      Name: or
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 6683CB00 66830C25 00000000 0183CBFF
+// CHECK-NEXT:   0010: 830C2500 0000002A 4883CB80 48830C25
+// CHECK-NEXT:   0020: 00000000 7F
+// CHECK-NEXT: )
+        .section or
+        or  $0, %bx
+        orw $1, bar
+        or  $-1, %ebx
+        orl $42, bar
+        or  $-128, %rbx
+        orq $127, bar
+
+// CHECK:      Name: xor
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 6683F301 66833425 00000000 FF83F32A
+// CHECK-NEXT:   0010: 83342500 00000080 4883F37F 48833425
+// CHECK-NEXT:   0020: 00000000 00
+// CHECK-NEXT: )
+        .section xor
+        xor  $1, %bx
+        xorw $-1, bar
+        xor  $42, %ebx
+        xorl $-128, bar
+        xor  $127, %rbx
+        xorq $0, bar
+
+// CHECK:      Name: add
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 6683C3FF 66830425 00000000 2A83C380
+// CHECK-NEXT:   0010: 83042500 0000007F 4883C300 48830425
+// CHECK-NEXT:   0020: 00000000 01
+// CHECK-NEXT: )
+        .section add
+        add  $-1, %bx
+        addw $42, bar
+        add  $-128, %ebx
+        addl $127, bar
+        add  $0, %rbx
+        addq $1, bar
+
+// CHECK:      Name: sub
+// CHECK:      SectionData (
+// CHECK-NEXT:   000: 6683EB2A 66832C25 00000000 8083EB7F
+// CHECK-NEXT:   010: 832C2500 00000000 4883EB01 48832C25
+// CHECK-NEXT:   020: 00000000 FF
+// CHECK-NEXT: )
+        .section sub
+        sub  $42, %bx
+        subw $-128, bar
+        sub  $127, %ebx
+        subl $0, bar
+        sub  $1, %rbx
+        subq $-1, bar
+
+// CHECK:      Name: cmp
+// CHECK:      SectionData (
+// CHECK-NEXT:   0000: 6683FB80 66833C25 00000000 7F83FB00
+// CHECK-NEXT:   0010: 833C2500 00000001 4883FBFF 48833C25
+// CHECK-NEXT:   0020: 00000000 2A
+// CHECK-NEXT: )
+        .section cmp
+        cmp  $-128, %bx
+        cmpw $127, bar
+        cmp  $0, %ebx
+        cmpl $1, bar
+        cmp  $-1, %rbx
+        cmpq $42, bar