diff --git a/include/llvm/Transforms/MutateStructTypes.h b/include/llvm/Transforms/MutateStructTypes.h
new file mode 100644
index 00000000000..1f3b2503803
--- /dev/null
+++ b/include/llvm/Transforms/MutateStructTypes.h
@@ -0,0 +1,87 @@
+//===- llvm/Transforms/MutateStructTypes.h - Change struct defns -*- C++ -*--=//
+//
+// This pass is used to change structure accesses and type definitions in some
+// way.  It can be used to arbitrarily permute structure fields, safely, without
+// breaking code.  A transformation may only be done on a type if that type has
+// been found to be "safe" by the 'FindUnsafePointerTypes' pass.  This pass will
+// assert and die if you try to do an illegal transformation.
+//
+// This is an interprocedural pass that requires the entire program to do a
+// transformation.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_MUTATESTRUCTTYPES_H
+#define LLVM_TRANSFORMS_MUTATESTRUCTTYPES_H
+
+#include "llvm/Pass.h"
+#include <map>
+
+class StructType;
+class GlobalValue;
+
+class MutateStructTypes : public Pass {
+  // TransformType - Representation of the destination type for a particular
+  // incoming structure.  The first member is the destination type that we are
+  // mapping to, and the second member is the destination slot # to put each
+  // incoming slot [or negative if the specified incoming slot should be
+  // removed].
+  //
+  typedef pair<const StructType*, vector<int> > TransformType;
+
+  // Transforms to do for each structure type...
+  map<const StructType*, TransformType> Transforms;
+
+  // Mapping of old type to new types...
+  map<const Type *, PATypeHolder<Type> > TypeMap;
+
+  // Mapping from global value of old type, to a global value of the new type...
+  map<const GlobalValue*, GlobalValue*> GlobalMap;
+
+  // Mapping from intra method value to intra method value
+  map<const Value*, Value*> LocalValueMap;
+
+public:
+  // Ctor - Take a map that specifies what transformation to do for each field
+  // of the specified structure types.  There is one element of the vector for
+  // each field of the structure.  The value specified indicates which slot of
+  // the destination structure the field should end up in.  A negative value 
+  // indicates that the field should be deleted entirely.
+  //
+  MutateStructTypes(const map<const StructType*, vector<int> > &Transforms);
+
+
+  // doPassInitialization - This loops over global constants defined in the
+  // module, converting them to their new type.  Also this creates placeholder
+  // methods for methods than need to be copied because they have a new
+  // signature type.
+  //
+  bool doPassInitialization(Module *M);
+
+  // doPerMethodWork - This transforms the instructions of the method to use the
+  // new types.
+  //
+  bool doPerMethodWork(Method *M);
+
+  // doPassFinalization - This removes the old versions of methods that are no
+  // longer needed.
+  //
+  virtual bool doPassFinalization(Module *M);
+
+private:
+  // ConvertType - Convert from the old type system to the new one...
+  const Type *ConvertType(const Type *Ty);
+
+  // ConvertValue - Convert from the old value in the old type system to the new
+  // type system.
+  //
+  Value *ConvertValue(const Value *V);
+
+  // AdjustIndices - Convert the indexes specifed by Idx to the new changed form
+  // using the specified OldTy as the base type being indexed into.
+  //
+  void AdjustIndices(const StructType *OldTy, vector<ConstPoolVal*> &Idx,
+                     unsigned idx = 0);
+};
+
+#endif