diff --git a/include/llvm/IR/MDBuilder.h b/include/llvm/IR/MDBuilder.h
index 074db78a767..ce81b5498f5 100644
--- a/include/llvm/IR/MDBuilder.h
+++ b/include/llvm/IR/MDBuilder.h
@@ -159,26 +159,26 @@ public:
   /// \brief Return metadata for a TBAA struct node in the type DAG
   /// with the given name, a list of pairs (offset, field type in the type DAG).
   MDNode *createTBAAStructTypeNode(StringRef Name,
-             ArrayRef<std::pair<uint64_t, MDNode*> > Fields) {
+             ArrayRef<std::pair<MDNode*, uint64_t> > Fields) {
     SmallVector<Value *, 4> Ops(Fields.size() * 2 + 1);
     Type *Int64 = IntegerType::get(Context, 64);
     Ops[0] = createString(Name);
     for (unsigned i = 0, e = Fields.size(); i != e; ++i) {
-      Ops[i * 2 + 1] = ConstantInt::get(Int64, Fields[i].first);
-      Ops[i * 2 + 2] = Fields[i].second;
+      Ops[i * 2 + 1] = Fields[i].first;
+      Ops[i * 2 + 2] = ConstantInt::get(Int64, Fields[i].second);
     }
     return MDNode::get(Context, Ops);
   }
 
   /// \brief Return metadata for a TBAA scalar type node with the
   /// given name, an offset and a parent in the TBAA type DAG.
-  MDNode *createTBAAScalarTypeNode(StringRef Name, uint64_t Offset,
-                                   MDNode *Parent) {
+  MDNode *createTBAAScalarTypeNode(StringRef Name, MDNode *Parent,
+                                   uint64_t Offset = 0) {
     SmallVector<Value *, 4> Ops(3);
     Type *Int64 = IntegerType::get(Context, 64);
     Ops[0] = createString(Name);
-    Ops[1] = ConstantInt::get(Int64, Offset);
-    Ops[2] = Parent;
+    Ops[1] = Parent;
+    Ops[2] = ConstantInt::get(Int64, Offset);
     return MDNode::get(Context, Ops);
   }
 
diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp
index 442145f5966..bbf3c3a2a5c 100644
--- a/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -134,6 +134,17 @@ namespace {
     uint64_t getOffset() const {
       return cast<ConstantInt>(Node->getOperand(2))->getZExtValue();
     }
+    /// TypeIsImmutable - Test if this TBAAStructTagNode represents a type for
+    /// objects which are not modified (by any means) in the context where this
+    /// AliasAnalysis is relevant.
+    bool TypeIsImmutable() const {
+      if (Node->getNumOperands() < 4)
+        return false;
+      ConstantInt *CI = dyn_cast<ConstantInt>(Node->getOperand(3));
+      if (!CI)
+        return false;
+      return CI->getValue()[0];
+    }
   };
 
   /// This is a simple wrapper around an MDNode which provides a
@@ -153,14 +164,24 @@ namespace {
     /// Get this TBAAStructTypeNode's field in the type DAG with
     /// given offset. Update the offset to be relative to the field type.
     TBAAStructTypeNode getParent(uint64_t &Offset) const {
+      // Parent can be omitted for the root node.
       if (Node->getNumOperands() < 2)
         return TBAAStructTypeNode();
 
+      // Special handling for a scalar type node. 
+      if (Node->getNumOperands() <= 3) {
+        MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(1));
+        if (!P)
+          return TBAAStructTypeNode();
+        return TBAAStructTypeNode(P);
+      }
+
       // Assume the offsets are in order. We return the previous field if
       // the current offset is bigger than the given offset.
       unsigned TheIdx = 0;
       for (unsigned Idx = 1; Idx < Node->getNumOperands(); Idx += 2) {
-        uint64_t Cur = cast<ConstantInt>(Node->getOperand(Idx))->getZExtValue();
+        uint64_t Cur = cast<ConstantInt>(Node->getOperand(Idx + 1))->
+                         getZExtValue();
         if (Cur > Offset) {
           assert(Idx >= 3 &&
                  "TBAAStructTypeNode::getParent should have an offset match!");
@@ -171,10 +192,10 @@ namespace {
       // Move along the last field.
       if (TheIdx == 0)
         TheIdx = Node->getNumOperands() - 2;
-      uint64_t Cur = cast<ConstantInt>(Node->getOperand(TheIdx))->
+      uint64_t Cur = cast<ConstantInt>(Node->getOperand(TheIdx + 1))->
                        getZExtValue();
       Offset -= Cur;
-      MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(TheIdx + 1));
+      MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(TheIdx));
       if (!P)
         return TBAAStructTypeNode();
       return TBAAStructTypeNode(P);
@@ -376,7 +397,8 @@ bool TypeBasedAliasAnalysis::pointsToConstantMemory(const Location &Loc,
 
   // If this is an "immutable" type, we can assume the pointer is pointing
   // to constant memory.
-  if (!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable())
+  if ((!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable()) ||
+      (EnableStructPathTBAA && TBAAStructTagNode(M).TypeIsImmutable()))
     return true;
 
   return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
@@ -392,7 +414,8 @@ TypeBasedAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
   // If this is an "immutable" type, we can assume the call doesn't write
   // to memory.
   if (const MDNode *M = CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa))
-    if (!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable())
+    if ((!EnableStructPathTBAA && TBAANode(M).TypeIsImmutable()) ||
+        (EnableStructPathTBAA && TBAAStructTagNode(M).TypeIsImmutable()))
       Min = OnlyReadsMemory;
 
   return ModRefBehavior(AliasAnalysis::getModRefBehavior(CS) & Min);
@@ -454,20 +477,14 @@ MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) {
   MDNode *T = A;
   while (T) {
     PathA.push_back(T);
-    if (EnableStructPathTBAA)
-      T = T->getNumOperands() >= 3 ? cast_or_null<MDNode>(T->getOperand(2)) : 0;
-    else
-      T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
+    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
   }
 
   SmallVector<MDNode *, 4> PathB;
   T = B;
   while (T) {
     PathB.push_back(T);
-    if (EnableStructPathTBAA)
-      T = T->getNumOperands() >= 3 ? cast_or_null<MDNode>(T->getOperand(2)) : 0;
-    else
-      T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
+    T = T->getNumOperands() >= 2 ? cast_or_null<MDNode>(T->getOperand(1)) : 0;
   }
 
   int IA = PathA.size() - 1;
diff --git a/test/Analysis/TypeBasedAliasAnalysis/tbaa-path.ll b/test/Analysis/TypeBasedAliasAnalysis/tbaa-path.ll
index c63abca3885..ee527639b3d 100644
--- a/test/Analysis/TypeBasedAliasAnalysis/tbaa-path.ll
+++ b/test/Analysis/TypeBasedAliasAnalysis/tbaa-path.ll
@@ -364,29 +364,29 @@ entry:
 attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
 
 !0 = metadata !{metadata !1, metadata !1, i64 0}
-!1 = metadata !{metadata !"any pointer", i64 0, metadata !2}
-!2 = metadata !{metadata !"omnipotent char", i64 0, metadata !3}
+!1 = metadata !{metadata !"any pointer", metadata !2}
+!2 = metadata !{metadata !"omnipotent char", metadata !3}
 !3 = metadata !{metadata !"Simple C/C++ TBAA"}
 !4 = metadata !{metadata !5, metadata !5, i64 0}
-!5 = metadata !{metadata !"long long", i64 0, metadata !2}
+!5 = metadata !{metadata !"long long", metadata !2}
 !6 = metadata !{metadata !7, metadata !7, i64 0}
-!7 = metadata !{metadata !"int", i64 0, metadata !2}
+!7 = metadata !{metadata !"int", metadata !2}
 !8 = metadata !{metadata !9, metadata !7, i64 4}
-!9 = metadata !{metadata !"_ZTS7StructA", i64 0, metadata !10, i64 4, metadata !7, i64 8, metadata !10, i64 12, metadata !7}
-!10 = metadata !{metadata !"short", i64 0, metadata !2}
+!9 = metadata !{metadata !"_ZTS7StructA", metadata !10, i64 0, metadata !7, i64 4, metadata !10, i64 8, metadata !7, i64 12}
+!10 = metadata !{metadata !"short", metadata !2}
 !11 = metadata !{metadata !9, metadata !10, i64 0}
 !12 = metadata !{metadata !13, metadata !7, i64 8}
-!13 = metadata !{metadata !"_ZTS7StructB", i64 0, metadata !10, i64 4, metadata !9, i64 20, metadata !7}
+!13 = metadata !{metadata !"_ZTS7StructB", metadata !10, i64 0, metadata !9, i64 4, metadata !7, i64 20}
 !14 = metadata !{metadata !13, metadata !10, i64 4}
 !15 = metadata !{metadata !13, metadata !7, i64 20}
 !16 = metadata !{metadata !13, metadata !7, i64 16}
 !17 = metadata !{metadata !18, metadata !7, i64 4}
-!18 = metadata !{metadata !"_ZTS7StructS", i64 0, metadata !10, i64 4, metadata !7}
+!18 = metadata !{metadata !"_ZTS7StructS", metadata !10, i64 0, metadata !7, i64 4}
 !19 = metadata !{metadata !18, metadata !10, i64 0}
 !20 = metadata !{metadata !21, metadata !7, i64 4}
-!21 = metadata !{metadata !"_ZTS8StructS2", i64 0, metadata !10, i64 4, metadata !7}
+!21 = metadata !{metadata !"_ZTS8StructS2", metadata !10, i64 0, metadata !7, i64 4}
 !22 = metadata !{metadata !21, metadata !10, i64 0}
 !23 = metadata !{metadata !24, metadata !7, i64 12}
-!24 = metadata !{metadata !"_ZTS7StructC", i64 0, metadata !10, i64 4, metadata !13, i64 28, metadata !7}
+!24 = metadata !{metadata !"_ZTS7StructC", metadata !10, i64 0, metadata !13, i64 4, metadata !7, i64 28}
 !25 = metadata !{metadata !26, metadata !7, i64 12}
-!26 = metadata !{metadata !"_ZTS7StructD", i64 0, metadata !10, i64 4, metadata !13, i64 28, metadata !7, i64 32, metadata !2}
+!26 = metadata !{metadata !"_ZTS7StructD", metadata !10, i64 0, metadata !13, i64 4, metadata !7, i64 28, metadata !2, i64 32}