diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index 0875257..b18f62b 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -934,7 +934,7 @@
 
 void RALinScan::DowngradeRegister(LiveInterval *li, unsigned Reg) {
   bool isNew = DowngradedRegs.insert(Reg);
-  isNew = isNew; // Silence compiler warning.
+  (void)isNew; // Silence compiler warning.
   assert(isNew && "Multiple reloads holding the same register?");
   DowngradeMap.insert(std::make_pair(li->reg, Reg));
   for (const unsigned *AS = tri_->getAliasSet(Reg); *AS; ++AS) {
diff --git a/lib/CodeGen/ScheduleDAGEmit.cpp b/lib/CodeGen/ScheduleDAGEmit.cpp
index 0a2fb37..6b7a8c6 100644
--- a/lib/CodeGen/ScheduleDAGEmit.cpp
+++ b/lib/CodeGen/ScheduleDAGEmit.cpp
@@ -57,7 +57,7 @@
       assert(I->getReg() && "Unknown physical register!");
       unsigned VRBase = MRI.createVirtualRegister(SU->CopyDstRC);
       bool isNew = VRBaseMap.insert(std::make_pair(SU, VRBase)).second;
-      isNew = isNew; // Silence compiler warning.
+      (void)isNew; // Silence compiler warning.
       assert(isNew && "Node emitted out of order - early");
       BuildMI(*BB, InsertPos, DebugLoc(), TII->get(TargetOpcode::COPY), VRBase)
         .addReg(I->getReg());
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index c334cf8..3402b9f 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -67,7 +67,7 @@
     if (IsClone)
       VRBaseMap.erase(Op);
     bool isNew = VRBaseMap.insert(std::make_pair(Op, SrcReg)).second;
-    isNew = isNew; // Silence compiler warning.
+    (void)isNew; // Silence compiler warning.
     assert(isNew && "Node emitted out of order - early");
     return;
   }
@@ -150,7 +150,7 @@
   if (IsClone)
     VRBaseMap.erase(Op);
   bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
-  isNew = isNew; // Silence compiler warning.
+  (void)isNew; // Silence compiler warning.
   assert(isNew && "Node emitted out of order - early");
 }
 
@@ -224,7 +224,7 @@
     if (IsClone)
       VRBaseMap.erase(Op);
     bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
-    isNew = isNew; // Silence compiler warning.
+    (void)isNew; // Silence compiler warning.
     assert(isNew && "Node emitted out of order - early");
   }
 }
@@ -496,7 +496,7 @@
      
   SDValue Op(Node, 0);
   bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
-  isNew = isNew; // Silence compiler warning.
+  (void)isNew; // Silence compiler warning.
   assert(isNew && "Node emitted out of order - early");
 }
 
@@ -518,7 +518,7 @@
 
   SDValue Op(Node, 0);
   bool isNew = VRBaseMap.insert(std::make_pair(Op, NewVReg)).second;
-  isNew = isNew; // Silence compiler warning.
+  (void)isNew; // Silence compiler warning.
   assert(isNew && "Node emitted out of order - early");
 }
 
@@ -555,7 +555,7 @@
   MBB->insert(InsertPos, MI);
   SDValue Op(Node, 0);
   bool isNew = VRBaseMap.insert(std::make_pair(Op, NewVReg)).second;
-  isNew = isNew; // Silence compiler warning.
+  (void)isNew; // Silence compiler warning.
   assert(isNew && "Node emitted out of order - early");
 }
 
diff --git a/lib/CodeGen/StackSlotColoring.cpp b/lib/CodeGen/StackSlotColoring.cpp
index 9b7f553..4a6ae60 100644
--- a/lib/CodeGen/StackSlotColoring.cpp
+++ b/lib/CodeGen/StackSlotColoring.cpp
@@ -646,7 +646,7 @@
   } else {
     SmallVector<MachineInstr*, 4> NewMIs;
     bool Success = TII->unfoldMemoryOperand(MF, MI, Reg, false, false, NewMIs);
-    Success = Success; // Silence compiler warning.
+    (void)Success; // Silence compiler warning.
     assert(Success && "Failed to unfold!");
     MachineInstr *NewMI = NewMIs[0];
     MBB->insert(MI, NewMI);