diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 480ee7f..611b045 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -141,8 +141,8 @@
 }
 
 MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
-  instr_iterator I = instr_begin();
-  while (I != end() && I->isPHI())
+  instr_iterator I = instr_begin(), E = instr_end();
+  while (I != E && I->isPHI())
     ++I;
   assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
   return I;
@@ -150,7 +150,8 @@
 
 MachineBasicBlock::iterator
 MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
-  while (I != end() && (I->isPHI() || I->isLabel() || I->isDebugValue()))
+  iterator E = end();
+  while (I != E && (I->isPHI() || I->isLabel() || I->isDebugValue()))
     ++I;
   // FIXME: This needs to change if we wish to bundle labels / dbg_values
   // inside the bundle.
@@ -160,29 +161,29 @@
 }
 
 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
-  iterator I = end();
-  while (I != begin() && ((--I)->isTerminator() || I->isDebugValue()))
+  iterator B = begin(), E = end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
     ; /*noop */
-  while (I != end() && !I->isTerminator())
+  while (I != E && !I->isTerminator())
     ++I;
   return I;
 }
 
 MachineBasicBlock::const_iterator
 MachineBasicBlock::getFirstTerminator() const {
-  const_iterator I = end();
-  while (I != begin() && ((--I)->isTerminator() || I->isDebugValue()))
+  const_iterator B = begin(), E = end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
     ; /*noop */
-  while (I != end() && !I->isTerminator())
+  while (I != E && !I->isTerminator())
     ++I;
   return I;
 }
 
 MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
-  instr_iterator I = instr_end();
-  while (I != instr_begin() && ((--I)->isTerminator() || I->isDebugValue()))
+  instr_iterator B = instr_begin(), E = instr_end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
     ; /*noop */
-  while (I != instr_end() && !I->isTerminator())
+  while (I != E && !I->isTerminator())
     ++I;
   return I;
 }
@@ -726,8 +727,9 @@
 
 MachineInstr *MachineBasicBlock::remove(MachineInstr *I) {
   if (I->isBundle()) {
-    MachineBasicBlock::instr_iterator MII = I; ++MII;
-    while (MII != end() && MII->isInsideBundle()) {
+    instr_iterator MII = llvm::next(I);
+    iterator E = end();
+    while (MII != E && MII->isInsideBundle()) {
       MachineInstr *MI = &*MII++;
       Insts.remove(MI);
     }