diff --git a/include/llvm/CodeGen/MachineFrameInfo.h b/include/llvm/CodeGen/MachineFrameInfo.h
index 93d77287d7c..0748b9ab24a 100644
--- a/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/include/llvm/CodeGen/MachineFrameInfo.h
@@ -493,11 +493,23 @@ public:
     return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
   }
 
+  /// CreateStackObjectWithMinAlign - Create a new statically sized stack
+  /// object, returning a nonnegative identifier to represent it. This function
+  /// takes a preferred alignment and a minimal alignment.
+  ///
+  int CreateStackObjectWithMinAlign(uint64_t Size, unsigned PrefAlignment,
+                        unsigned MinAlignment, bool isSS,
+                        bool MayNeedSP = false, const AllocaInst *Alloca = 0);
+
   /// CreateStackObject - Create a new statically sized stack object, returning
-  /// a nonnegative identifier to represent it.
+  /// a nonnegative identifier to represent it. Will not emit an error when
+  /// Alignment can't be satisfied.
   ///
   int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS,
-                        bool MayNeedSP = false, const AllocaInst *Alloca = 0);
+                        bool MayNeedSP = false, const AllocaInst *Alloca = 0) {
+    return CreateStackObjectWithMinAlign(Size, Alignment, 0, isSS,
+                                         MayNeedSP, Alloca);
+  }
 
   /// CreateSpillStackObject - Create a new statically sized stack object that
   /// represents a spill slot, returning a nonnegative identifier to represent
@@ -517,7 +529,8 @@ public:
   /// variable sized object is created, whether or not the index returned is
   /// actually used.
   ///
-  int CreateVariableSizedObject(unsigned Alignment);
+  int CreateVariableSizedObject(unsigned PrefAlignment, unsigned MinAlignment,
+                                const AllocaInst *Alloca = 0);
 
   /// getCalleeSavedInfo - Returns a reference to call saved info vector for the
   /// current function.
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 9647e83e24c..3d7d20d4160 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -473,24 +473,32 @@ void MachineFrameInfo::ensureMaxAlignment(unsigned Align) {
 }
 
 /// clampStackAlignment - Clamp the alignment if requested and emit a warning.
-static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align,
-                                           unsigned StackAlign) {
-  if (!ShouldClamp || Align <= StackAlign)
-    return Align;
-  DEBUG(dbgs() << "Warning: requested alignment " << Align
-               << " exceeds the stack alignment " << StackAlign
-               << " when stack realignment is off" << '\n');
+static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned PrefAlign,
+                         unsigned MinAlign, unsigned StackAlign,
+                         const AllocaInst *Alloca = 0) {
+  if (!ShouldClamp || PrefAlign <= StackAlign)
+    return PrefAlign;
+  if (Alloca && MinAlign > StackAlign)
+    Alloca->getParent()->getContext().emitError(Alloca,
+        "Requested Minimal Alignment exceeds the Stack Alignment!");
+  else
+    assert(MinAlign <= StackAlign &&
+           "Requested Minimal Alignment exceeds the Stack Alignment!");
   return StackAlign;
 }
 
-/// CreateStackObject - Create a new statically sized stack object, returning
-/// a nonnegative identifier to represent it.
+/// CreateStackObjectWithMinAlign - Create a new statically sized stack
+/// object, returning a nonnegative identifier to represent it. This function
+/// takes a preferred alignment and a minimal alignment.
 ///
-int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
-                      bool isSS, bool MayNeedSP, const AllocaInst *Alloca) {
+int MachineFrameInfo::CreateStackObjectWithMinAlign(uint64_t Size,
+                          unsigned PrefAlignment, unsigned MinAlignment,
+                          bool isSS, bool MayNeedSP, const AllocaInst *Alloca) {
   assert(Size != 0 && "Cannot allocate zero size stack objects!");
-  Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                                  Alignment, TFI.getStackAlignment());
+  unsigned Alignment = clampStackAlignment(
+                           !TFI.isStackRealignable() || !RealignOption,
+                           PrefAlignment, MinAlignment,
+                           TFI.getStackAlignment(), Alloca);
   Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP,
                                 Alloca));
   int Index = (int)Objects.size() - NumFixedObjects - 1;
@@ -506,7 +514,8 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
 int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
                                              unsigned Alignment) {
   Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                                  Alignment, TFI.getStackAlignment()); 
+                                  Alignment, 0,
+                                  TFI.getStackAlignment()); 
   CreateStackObject(Size, Alignment, true, false);
   int Index = (int)Objects.size() - NumFixedObjects - 1;
   ensureMaxAlignment(Alignment);
@@ -518,10 +527,13 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
 /// variable sized object is created, whether or not the index returned is
 /// actually used.
 ///
-int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment) {
+int MachineFrameInfo::CreateVariableSizedObject(unsigned PrefAlignment,
+                        unsigned MinAlignment, const AllocaInst *Alloca) {
   HasVarSizedObjects = true;
-  Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                                  Alignment, TFI.getStackAlignment()); 
+  unsigned Alignment = clampStackAlignment(
+                           !TFI.isStackRealignable() || !RealignOption,
+                           PrefAlignment, MinAlignment,
+                           TFI.getStackAlignment(), Alloca); 
   Objects.push_back(StackObject(0, Alignment, 0, false, false, true, 0));
   ensureMaxAlignment(Alignment);
   return (int)Objects.size()-NumFixedObjects-1;
@@ -542,7 +554,7 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
   unsigned StackAlign = TFI.getStackAlignment();
   unsigned Align = MinAlign(SPOffset, StackAlign);
   Align = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                              Align, TFI.getStackAlignment()); 
+                              Align, 0, TFI.getStackAlignment()); 
   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
                                               /*isSS*/   false,
                                               /*NeedSP*/ false,
diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index b46edad7a3d..229c50be9a1 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -95,7 +95,8 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
            (TySize >= 8 && isa<ArrayType>(Ty) &&
             cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
         StaticAllocaMap[AI] =
-          MF->getFrameInfo()->CreateStackObject(TySize, Align, false,
+          MF->getFrameInfo()->CreateStackObjectWithMinAlign(TySize, Align,
+                                                AI->getAlignment(), false,
                                                 MayNeedSP, AI);
       }
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8c22db35cb1..ee98b00e2b5 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3259,7 +3259,8 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
 
   // Inform the Frame Information that we have just allocated a variable-sized
   // object.
-  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1);
+  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1,
+                                 I.getAlignment(), &I);
 }
 
 void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
diff --git a/test/CodeGen/ARM/alloc-no-stack-realign-error.ll b/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
new file mode 100644
index 00000000000..96c00174dba
--- /dev/null
+++ b/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -mtriple=armv7-apple-ios -O0 -realign-stack=0 2>&1 | FileCheck %s
+
+; rdar://12713765
+@T3_retval = common global <16 x float> zeroinitializer, align 16
+
+; If alignment for alloc is smaller than or equal to stack alignment, but the 
+; preferred type alignment is bigger, the alignment will be clamped.
+; If alignment for alloca is bigger than stack alignment, the compiler
+; will emit an error.
+define void @test(<16 x float>* noalias sret %agg.result) nounwind ssp {
+entry:
+; CHECK: Requested Minimal Alignment exceeds the Stack Alignment!
+ %retval = alloca <16 x float>, align 16
+ %0 = load <16 x float>* @T3_retval, align 16
+ store <16 x float> %0, <16 x float>* %retval
+ %1 = load <16 x float>* %retval
+ store <16 x float> %1, <16 x float>* %agg.result, align 16
+ ret void
+}
diff --git a/test/CodeGen/ARM/alloc-no-stack-realign.ll b/test/CodeGen/ARM/alloc-no-stack-realign.ll
index 273041dee34..94adc9c67de 100644
--- a/test/CodeGen/ARM/alloc-no-stack-realign.ll
+++ b/test/CodeGen/ARM/alloc-no-stack-realign.ll
@@ -39,7 +39,7 @@ entry:
 ; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
 ; NO-REALIGN: vst1.64
 ; NO-REALIGN: vst1.64
- %retval = alloca <16 x float>, align 16
+ %retval = alloca <16 x float>, align 4
  %0 = load <16 x float>* @T3_retval, align 16
  store <16 x float> %0, <16 x float>* %retval
  %1 = load <16 x float>* %retval