diff --git a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
--- a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -206,10 +206,6 @@
     /// T2JumpTables - Keep track of all the Thumb2 jumptable instructions.
     SmallVector<MachineInstr*, 4> T2JumpTables;
 
-    /// HasFarJump - True if any far jump instruction has been emitted during
-    /// the branch fix up pass.
-    bool HasFarJump;
-
     MachineFunction *MF;
     MachineConstantPool *MCP;
     const ARMBaseInstrInfo *TII;
@@ -270,7 +266,6 @@
     bool fixupImmediateBr(ImmBranch &Br);
     bool fixupConditionalBr(ImmBranch &Br);
     bool fixupUnconditionalBr(ImmBranch &Br);
-    bool undoLRSpillRestore();
     bool optimizeThumb2Instructions();
     bool optimizeThumb2Branches();
     bool reorderThumb2JumpTables();
@@ -363,7 +358,6 @@
   isThumb1 = AFI->isThumb1OnlyFunction();
   isThumb2 = AFI->isThumb2Function();
 
-  HasFarJump = false;
   bool GenerateTBB = isThumb2 || (isThumb1 && SynthesizeThumb1TBB);
 
   // Renumber all of the machine basic blocks in the function, guaranteeing that
@@ -456,11 +450,6 @@
   // After a while, this might be made debug-only, but it is not expensive.
   verify();
 
-  // If LR has been forced spilled and no far jump (i.e. BL) has been issued,
-  // undo the spill / restore of LR if possible.
-  if (isThumb && !HasFarJump && AFI->isLRSpilledForFarJump())
-    MadeChange |= undoLRSpillRestore();
-
   // Save the mapping between original and cloned constpool entries.
   for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
     for (unsigned j = 0, je = CPEntries[i].size(); j != je; ++j) {
@@ -1633,7 +1622,6 @@
   BBInfoVector &BBInfo = BBUtils->getBBInfo();
   BBInfo[MBB->getNumber()].Size += 2;
   BBUtils->adjustBBOffsetsAfter(MBB);
-  HasFarJump = true;
   ++NumUBrFixed;
 
   LLVM_DEBUG(dbgs() << "  Changed B to long jump " << *MI);
@@ -1735,34 +1723,6 @@
   return true;
 }
 
-/// undoLRSpillRestore - Remove Thumb push / pop instructions that only spills
-/// LR / restores LR to pc. FIXME: This is done here because it's only possible
-/// to do this if tBfar is not used.
-bool ARMConstantIslands::undoLRSpillRestore() {
-  bool MadeChange = false;
-  for (unsigned i = 0, e = PushPopMIs.size(); i != e; ++i) {
-    MachineInstr *MI = PushPopMIs[i];
-    // First two operands are predicates.
-    if (MI->getOpcode() == ARM::tPOP_RET &&
-        MI->getOperand(2).getReg() == ARM::PC &&
-        MI->getNumExplicitOperands() == 3) {
-      // Create the new insn and copy the predicate from the old.
-      BuildMI(MI->getParent(), MI->getDebugLoc(), TII->get(ARM::tBX_RET))
-          .add(MI->getOperand(0))
-          .add(MI->getOperand(1));
-      MI->eraseFromParent();
-      MadeChange = true;
-    } else if (MI->getOpcode() == ARM::tPUSH &&
-               MI->getOperand(2).getReg() == ARM::LR &&
-               MI->getNumExplicitOperands() == 3) {
-      // Just remove the push.
-      MI->eraseFromParent();
-      MadeChange = true;
-    }
-  }
-  return MadeChange;
-}
-
 bool ARMConstantIslands::optimizeThumb2Instructions() {
   bool MadeChange = false;
 
diff --git a/llvm/test/CodeGen/Thumb/remove-unneeded-push-pop.ll b/llvm/test/CodeGen/Thumb/remove-unneeded-push-pop.ll
--- a/llvm/test/CodeGen/Thumb/remove-unneeded-push-pop.ll
+++ b/llvm/test/CodeGen/Thumb/remove-unneeded-push-pop.ll
@@ -5,8 +5,15 @@
 
 define hidden void @foo() {
 entry:
-; CHECK-NOT: push	{lr}
-; CHECK-NOT: pop	{pc}
+; undoLRSpillRestore() in ARMConstantIsland is not safe, as PrologEpilogInserter
+; ensures stack alignment when LR is spilled.
+; This test previously check 'push {lr}' gets erased, as mis-alignment happened when
+; 'pop {pc}' is erased. However, erasing 'push {lr}' will cause the stack mis-aligned
+; when StackAlignment is 8 (functions contain call/alloc).
+; Therefore, we keep LR spill/restore.
+;
+; CHECK: push	{lr}
+; CHECK: pop	{pc}
   store i32 24654, i32* @f, align 4
   br label %if.end
 
diff --git a/llvm/test/CodeGen/Thumb/stack-mis-alignment.ll b/llvm/test/CodeGen/Thumb/stack-mis-alignment.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/Thumb/stack-mis-alignment.ll
@@ -0,0 +1,18 @@
+; RUN: llc -O0 < %s | FileCheck %s
+
+; For noreturn function with StackAlignment 8 (function contains call/alloc),
+; check that lr is saved to keep the stack aligned.
+; CHECK: push    {lr}
+
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv5e-none-linux-gnueabi"
+
+define dso_local i32 @f() noreturn nounwind {
+entry:
+  call i32 @llvm.arm.space(i32 2048, i32 undef)
+  tail call i32 @exit(i32 0)
+  unreachable
+}
+
+declare i32 @llvm.arm.space(i32, i32)
+declare dso_local i32 @exit(i32)