diff --git a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
index 94a5355c9167..236942cb6efd 100644
--- a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
@@ -220,7 +220,8 @@ protected:
   bool needMigrateBlock(MachineBasicBlock *MBB) const;
 
   // Utility Functions
-  void reversePredicateSetter(MachineBasicBlock::iterator I);
+  void reversePredicateSetter(MachineBasicBlock::iterator I,
+                              MachineBasicBlock &MBB);
   /// Compute the reversed DFS post order of Blocks
   void orderBlocks(MachineFunction *MF);
 
@@ -422,9 +423,11 @@ bool AMDGPUCFGStructurizer::needMigrateBlock(MachineBasicBlock *MBB) const {
 }
 
 void AMDGPUCFGStructurizer::reversePredicateSetter(
-    MachineBasicBlock::iterator I) {
+    MachineBasicBlock::iterator I, MachineBasicBlock &MBB) {
   assert(I.isValid() && "Expected valid iterator");
   for (;; --I) {
+    if (I == MBB.end())
+      continue;
     if (I->getOpcode() == AMDGPU::PRED_X) {
       switch (I->getOperand(2).getImm()) {
       case OPCODE_IS_ZERO_INT:
@@ -991,7 +994,7 @@ int AMDGPUCFGStructurizer::ifPatternMatch(MachineBasicBlock *MBB) {
     // Triangle pattern, true is empty
     // We reverse the predicate to make a triangle, empty false pattern;
     std::swap(TrueMBB, FalseMBB);
-    reversePredicateSetter(MBB->end());
+    reversePredicateSetter(MBB->end(), *MBB);
     LandBlk = FalseMBB;
     FalseMBB = nullptr;
   } else if (FalseMBB->succ_size() == 1
@@ -1501,7 +1504,7 @@ void AMDGPUCFGStructurizer::mergeLoopbreakBlock(MachineBasicBlock *ExitingMBB,
   MachineBasicBlock *TrueBranch = getTrueBranch(BranchMI);
   MachineBasicBlock::iterator I = BranchMI;
   if (TrueBranch != LandMBB)
-    reversePredicateSetter(I);
+    reversePredicateSetter(I, *I->getParent());
   insertCondBranchBefore(ExitingMBB, I, AMDGPU::IF_PREDICATE_SET, AMDGPU::PREDICATE_BIT, DL);
   insertInstrBefore(I, AMDGPU::BREAK);
   insertInstrBefore(I, AMDGPU::ENDIF);
diff --git a/llvm/lib/Target/AMDGPU/R600EmitClauseMarkers.cpp b/llvm/lib/Target/AMDGPU/R600EmitClauseMarkers.cpp
index 93ed5be94a54..783dba43aaf7 100644
--- a/llvm/lib/Target/AMDGPU/R600EmitClauseMarkers.cpp
+++ b/llvm/lib/Target/AMDGPU/R600EmitClauseMarkers.cpp
@@ -307,7 +307,7 @@ public:
                                                     BB != BB_E; ++BB) {
       MachineBasicBlock &MBB = *BB;
       MachineBasicBlock::iterator I = MBB.begin();
-      if (I->getOpcode() == AMDGPU::CF_ALU)
+      if (I != MBB.end() && I->getOpcode() == AMDGPU::CF_ALU)
         continue; // BB was already parsed
       for (MachineBasicBlock::iterator E = MBB.end(); I != E;) {
         if (isALU(*I))
diff --git a/llvm/lib/Target/AMDGPU/R600ISelLowering.cpp b/llvm/lib/Target/AMDGPU/R600ISelLowering.cpp
index 21854affe5aa..560fe0a16df8 100644
--- a/llvm/lib/Target/AMDGPU/R600ISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/R600ISelLowering.cpp
@@ -205,6 +205,8 @@ const R600Subtarget *R600TargetLowering::getSubtarget() const {
 }
 
 static inline bool isEOP(MachineBasicBlock::iterator I) {
+  if (std::next(I) == I->getParent()->end())
+    return false;
   return std::next(I)->getOpcode() == AMDGPU::RETURN;
 }
 
diff --git a/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp b/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
index 9e972a569a0f..7c220306cc5c 100644
--- a/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
@@ -158,10 +158,11 @@ MachineBasicBlock::iterator
 SILoadStoreOptimizer::findMatchingDSInst(MachineBasicBlock::iterator I,
                                          unsigned EltSize){
   MachineBasicBlock::iterator E = I->getParent()->end();
+  MachineBasicBlock &MBB = *I->getParent();
   MachineBasicBlock::iterator MBBI = I;
   ++MBBI;
 
-  if (MBBI->getOpcode() != I->getOpcode())
+  if (MBBI == MBB.end() || MBBI->getOpcode() != I->getOpcode())
     return E;
 
   // Don't merge volatiles.
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 7318e788a22a..9f5a0c6134c6 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -156,8 +156,10 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
 
   const TargetRegisterClass &AvailableRegs = *TRI->getGPRsForTailCall(*MF);
 
-  unsigned Opc = MBBI->getOpcode();
-  switch (Opc) {
+  if (MBBI == MBB.end())
+    return 0;
+
+  switch (MBBI->getOpcode()) {
   default: return 0;
   case TargetOpcode::PATCHABLE_RET:
   case X86::RET: