Index: lib/Target/X86/X86InstrInfo.cpp
===================================================================
--- lib/Target/X86/X86InstrInfo.cpp
+++ lib/Target/X86/X86InstrInfo.cpp
@@ -6298,14 +6298,30 @@
   return isHighLatencyDef(DefMI->getOpcode());
 }
 
-static bool hasVirtualRegDefsInBasicBlock(const MachineInstr &Inst,
-                                          const MachineBasicBlock *MBB) {
-  assert(Inst.getNumOperands() == 3 && "Reassociation needs binary operators");
+static bool hasReassociableOperands(const MachineInstr &Inst,
+                                    const MachineBasicBlock *MBB) {
+  assert((Inst.getNumOperands() == 3 || Inst.getNumOperands() == 4) &&
+         "Reassociation needs binary operators");
   const MachineOperand &Op1 = Inst.getOperand(1);
   const MachineOperand &Op2 = Inst.getOperand(2);
   const MachineRegisterInfo &MRI = MBB->getParent()->getRegInfo();
 
-  // We need virtual register definitions.
+  // Integer binary math/logic instructions have a third source operand:
+  // the EFLAGS register. That operand must be both defined here and never
+  // used; ie, it must be dead. If the EFLAGS operand is live, then we can
+  // not change anything because rearranging the operands could affect other
+  // instructions that depend on the exact status flags (zero, sign, etc.)
+  // that are set by using these particular operands with this operation.
+  if (Inst.getNumOperands() == 4) {
+    assert(Inst.getOperand(3).isReg() &&
+           Inst.getOperand(3).getReg() == X86::EFLAGS &&
+           "Unexpected operand in reassociable instruction");
+    if (!Inst.getOperand(3).isDead())
+      return false;
+  }
+  
+  // We need virtual register definitions for the operands that we will
+  // reassociate.
   MachineInstr *MI1 = nullptr;
   MachineInstr *MI2 = nullptr;
   if (Op1.isReg() && TargetRegisterInfo::isVirtualRegister(Op1.getReg()))
@@ -6338,7 +6354,7 @@
   //    operands in the same basic block as Inst.
   // 3. The previous instruction's result must only be used by Inst.
   if (MI1->getOpcode() == AssocOpcode &&
-      hasVirtualRegDefsInBasicBlock(*MI1, MBB) &&
+      hasReassociableOperands(*MI1, MBB) &&
       MRI.hasOneNonDBGUse(MI1->getOperand(0).getReg()))
     return true;
 
@@ -6350,6 +6366,10 @@
 //       2. Other math / logic operations (and, or)
 static bool isAssociativeAndCommutative(const MachineInstr &Inst) {
   switch (Inst.getOpcode()) {
+  case X86::IMUL16rr:
+  case X86::IMUL32rr:
+  case X86::IMUL64rr:
+    return true;
   case X86::ADDSDrr:
   case X86::ADDSSrr:
   case X86::VADDSDrr:
@@ -6375,7 +6395,7 @@
   //    operands in the same basic block.
   // 3. The instruction must have a reassociable sibling.
   if (isAssociativeAndCommutative(Inst) &&
-      hasVirtualRegDefsInBasicBlock(Inst, Inst.getParent()) &&
+      hasReassociableOperands(Inst, Inst.getParent()) &&
       hasReassocSibling(Inst, Commuted))
     return true;
 
Index: test/CodeGen/X86/machine-combiner-int.ll
===================================================================
--- test/CodeGen/X86/machine-combiner-int.ll
+++ test/CodeGen/X86/machine-combiner-int.ll
@@ -0,0 +1,43 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=x86-64 < %s | FileCheck %s
+
+; Verify that integer multiplies are reassociated. The first multiply in 
+; each test should be independent of the result of the preceding add (lea).
+
+define i16 @reassociate_muls_i16(i16 %x0, i16 %x1, i16 %x2, i16 %x3) {
+; CHECK-LABEL: reassociate_muls_i16:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    leal   (%rdi,%rsi), %eax
+; CHECK-NEXT:    imull  %ecx, %edx
+; CHECK-NEXT:    imull  %edx, %eax
+; CHECK-NEXT:    retq
+  %t0 = add i16 %x0, %x1
+  %t1 = mul i16 %x2, %t0
+  %t2 = mul i16 %x3, %t1
+  ret i16 %t2
+}
+
+define i32 @reassociate_muls_i32(i32 %x0, i32 %x1, i32 %x2, i32 %x3) {
+; CHECK-LABEL: reassociate_muls_i32:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    leal   (%rdi,%rsi), %eax
+; CHECK-NEXT:    imull  %ecx, %edx
+; CHECK-NEXT:    imull  %edx, %eax
+; CHECK-NEXT:    retq
+  %t0 = add i32 %x0, %x1
+  %t1 = mul i32 %x2, %t0
+  %t2 = mul i32 %x3, %t1
+  ret i32 %t2
+}
+
+define i64 @reassociate_muls_i64(i64 %x0, i64 %x1, i64 %x2, i64 %x3) {
+; CHECK-LABEL: reassociate_muls_i64:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    leaq   (%rdi,%rsi), %rax
+; CHECK-NEXT:    imulq  %rcx, %rdx
+; CHECK-NEXT:    imulq  %rdx, %rax
+; CHECK-NEXT:    retq
+  %t0 = add i64 %x0, %x1
+  %t1 = mul i64 %x2, %t0
+  %t2 = mul i64 %x3, %t1
+  ret i64 %t2
+}