diff --git a/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.cpp b/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.cpp
index b96ae54..65309ea 100644
--- a/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.cpp
+++ b/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.cpp
@@ -73,7 +73,7 @@
   DbgInfo.BeginFunction(MF);
 
   // Emit the autos section of function.
-  EmitAutos(CurrentFnName);
+  EmitAutos(F);
 
   // Now emit the instructions of function in its code section.
   const MCSection *fCodeSection = 
@@ -362,9 +362,10 @@
   const TargetData *TD = TM.getTargetData();
   // Emit the data section name.
   O << "\n"; 
-  
+ 
+  std::string SectionName = getObjFileLowering().getNameForFunctFrame(F);
   const MCSection *fPDataSection =
-    getObjFileLowering().getSectionForFunctionFrame(CurrentFnName);
+    getObjFileLowering().getSectionForFunctionFrame(SectionName); 
   OutStreamer.SwitchSection(fPDataSection);
   
   // Emit function frame label
@@ -440,12 +441,12 @@
   }
 }
 
-void PIC16AsmPrinter::EmitAutos(std::string FunctName) {
+void PIC16AsmPrinter::EmitAutos(const Function *F) {
   // Section names for all globals are already set.
   const TargetData *TD = TM.getTargetData();
 
   // Now print Autos section for this function.
-  std::string SectionName = PAN::getAutosSectionName(FunctName);
+  std::string SectionName = PAN::getAutosSectionName(CurrentFnName);
 
   // If this function is a cloned function then the name of auto section 
   // will not be present in the list of existing section. Hence this section
@@ -459,6 +460,15 @@
     if (AutosSections[i]->S_->getName() == SectionName) { 
       // Set the printing status to true
       AutosSections[i]->setPrintedStatus(true);
+      // Overlay auto sections with same function color.
+      std::string BaseSectionName = getObjFileLowering().
+                                    getNameForFunctFrame(F, true);
+      if (BaseSectionName != F->getName()) {
+        std::string NewSectionName = PAN::getAutosSectionName(BaseSectionName);
+        const_cast<MCSectionPIC16 *>(AutosSections[i]->S_)->setName(
+                                                            NewSectionName);
+      }
+
       OutStreamer.SwitchSection(AutosSections[i]->S_);
       const std::vector<const GlobalVariable*> &Items = AutosSections[i]->Items;
       for (unsigned j = 0; j < Items.size(); j++) {
diff --git a/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.h b/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.h
index 55a2fcf..ece19ca 100644
--- a/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.h
+++ b/lib/Target/PIC16/AsmPrinter/PIC16AsmPrinter.h
@@ -52,7 +52,7 @@
     void EmitDefinedVars (Module &M);
     void EmitIData (Module &M);
     void EmitUData (Module &M);
-    void EmitAutos (std::string FunctName);
+    void EmitAutos (const Function *F);
     void EmitRemainingAutos ();
     void EmitRomData (Module &M);
     void EmitFunctionFrame(MachineFunction &MF);
diff --git a/lib/Target/PIC16/MCSectionPIC16.h b/lib/Target/PIC16/MCSectionPIC16.h
index 66607c8..cfc8dd0 100644
--- a/lib/Target/PIC16/MCSectionPIC16.h
+++ b/lib/Target/PIC16/MCSectionPIC16.h
@@ -28,7 +28,8 @@
   public:
     
     const std::string &getName() const { return Name; }
-    
+
+    void setName(std::string name) { Name = name; }    
     static MCSectionPIC16 *Create(const StringRef &Name, 
                                   SectionKind K, MCContext &Ctx);
     
diff --git a/lib/Target/PIC16/PIC16.h b/lib/Target/PIC16/PIC16.h
index 29f9079..073eb47 100644
--- a/lib/Target/PIC16/PIC16.h
+++ b/lib/Target/PIC16/PIC16.h
@@ -44,6 +44,7 @@
     UGE
   };
 }
+
   // External symbol names require memory to live till the program end.
   // So we have to allocate it and keep.
   inline static const char *createESName (const std::string &name) {
diff --git a/lib/Target/PIC16/PIC16PAN.h b/lib/Target/PIC16/PIC16PAN.h
index cca8f35..f0e1ba0 100644
--- a/lib/Target/PIC16/PIC16PAN.h
+++ b/lib/Target/PIC16/PIC16PAN.h
@@ -22,8 +22,19 @@
 #include <cassert>
 #include <cstring>
 #include <string>
-
 namespace llvm {
+namespace PIC16Overlay {
+  // Implement Overlay through colors because we may want to enhance overlay
+  // architecture later. More colors can be added then. 
+  // Idea here is that functions with same color can be overlayed.
+  enum Overlay {
+    // A color name can only consist of upper case letters and underscore.
+    GREEN, // Stands for mainline functions that can be overlayed.
+    GREEN_IL, // Interrupt line version of GREEN.
+    RED // Stands for functions that can not be overlayed.
+  };
+}
+
   // A Central class to manage all ABI naming conventions.
   // PAN - [P]ic16 [A]BI [N]ames
   class PAN {
@@ -414,6 +425,27 @@
         }
       }
     }
+    inline static std::string getOverlayStr(unsigned Color) {
+      std::string Str = "Overlay=";
+      Str.append(getSectionNameForColor(Color));
+      return Str;
+    }
+
+    inline static std::string getSectionNameForColor(unsigned Color) {
+      switch (Color) {
+        case PIC16Overlay::GREEN:
+          return "GREEN";
+        case PIC16Overlay::GREEN_IL:
+          return "GREEN_IL";
+        default:
+          assert( 0 && "Color not supported");
+      }   
+    }
+
+    inline static std::string getAutosSectionForColor(std::string Color) {
+      return Color.append("_AUTOS");
+    }
+
   }; // class PAN.
 
 } // end namespace llvm;
diff --git a/lib/Target/PIC16/PIC16Passes/Makefile b/lib/Target/PIC16/PIC16Passes/Makefile
index 9195621..61b4362 100644
--- a/lib/Target/PIC16/PIC16Passes/Makefile
+++ b/lib/Target/PIC16/PIC16Passes/Makefile
@@ -12,5 +12,8 @@
 
 LOADABLE_MODULE = 1
 
+# Hack: we need to include 'main' pic16 target directory to grab private headers
+CPPFLAGS = -I$(PROJ_OBJ_DIR)/.. -I$(PROJ_SRC_DIR)/..
+
 include $(LEVEL)/Makefile.common
 
diff --git a/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.cpp b/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.cpp
new file mode 100644
index 0000000..cfeb97d
--- /dev/null
+++ b/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.cpp
@@ -0,0 +1,69 @@
+//===-- PIC16FrameOverlay.cpp - Implementation for PIC16 Frame Overlay===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source 
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the PIC16 Frame Overlay implementation.
+//
+//===----------------------------------------------------------------------===//
+
+
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Pass.h"
+#include "llvm/Module.h"
+#include "llvm/Support/raw_ostream.h"
+#include "PIC16.h"
+#include "PIC16FrameOverlay.h"
+#include <vector>
+#include <iostream>
+using namespace llvm;
+using std::vector;
+using std::string;
+
+
+void PIC16FrameOverlay::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesCFG();
+  AU.addRequired<CallGraph>();
+}
+
+bool PIC16FrameOverlay::runOnModule(Module &M) {
+  CallGraph &CG = getAnalysis<CallGraph>();
+  for (CallGraph::iterator it = CG.begin() ; it != CG.end(); it++)
+  {
+    // External calling node doesn't have any function associated 
+    // with it
+    if (!it->first)
+      continue;
+
+    if (it->second->size() == 0) {
+      if (PAN::isInterruptLineFunction(it->first))
+        ColorFunction(it->second, PIC16Overlay::GREEN_IL);
+      else 
+        ColorFunction(it->second, PIC16Overlay::GREEN);
+    }
+  }
+  return false;
+}
+
+void PIC16FrameOverlay::ColorFunction(CallGraphNode *CGN, unsigned Color) {
+  switch (Color) {
+    case PIC16Overlay::GREEN:
+    case PIC16Overlay::GREEN_IL: {
+      Function *LeafFunct = CGN->getFunction();
+      std::string Section = "";
+      if (LeafFunct->hasSection()) {
+        Section = LeafFunct->getSection();
+        Section.append(" ");
+      }
+      Section.append(PAN::getOverlayStr(Color));
+      LeafFunct->setSection(Section);
+      break;
+    }
+    default:
+      assert( 0 && "Color not supported");   
+  }
+}
diff --git a/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.h b/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.h
new file mode 100644
index 0000000..813ceba
--- /dev/null
+++ b/lib/Target/PIC16/PIC16Passes/PIC16FrameOverlay.h
@@ -0,0 +1,45 @@
+//===-- PIC16FrameOverlay.h - Interface for PIC16 Frame Overlay -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source 
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the PIC16 Frame Overlay infrastructure.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef PIC16FRAMEOVERLAY_H
+#define PIC16FRAMEOVERLAY_H
+ 
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Pass.h"
+#include "llvm/Module.h"
+#include "llvm/Support/raw_ostream.h"
+#include <vector>
+#include <iostream>
+using std::vector;
+using std::string;
+using namespace llvm;
+
+namespace  { 
+
+  class PIC16FrameOverlay : public ModulePass { 
+  public:
+    static char ID; // Class identification 
+    PIC16FrameOverlay() : ModulePass(&ID)  {}
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const; 
+    virtual bool runOnModule(Module &M); 
+  private: 
+    void ColorFunction(CallGraphNode *CGN, unsigned Color);
+  };
+  char PIC16FrameOverlay::ID = 0;
+  static RegisterPass<PIC16FrameOverlay>
+  Y("pic16overlay", "PIC16 Frame Overlay Analysis");
+
+}  // End of  namespace
+
+#endif
diff --git a/lib/Target/PIC16/PIC16TargetObjectFile.cpp b/lib/Target/PIC16/PIC16TargetObjectFile.cpp
index 3ff27a9..4c2349f 100644
--- a/lib/Target/PIC16/PIC16TargetObjectFile.cpp
+++ b/lib/Target/PIC16/PIC16TargetObjectFile.cpp
@@ -82,6 +82,35 @@
   return getPIC16Section(T.c_str(), SectionKind::getDataRel());
 }
 
+std::string PIC16TargetObjectFile::getNameForFunctFrame(const Function *F,
+                                                          bool IsAutosSection) {
+  std::string SectionName = F->getName();
+  if (F->hasSection()) {
+    std::string Sectn = F->getSection();
+    std::string StrToFind = "Overlay=";
+    unsigned Pos = Sectn.find(StrToFind);
+    if (Pos != std::string::npos) {
+      Pos += StrToFind.length();
+      std::string Color = "";
+      char c = Sectn.at(Pos);
+      // A Color can only consist on upper case letters or underscore.
+      while ((c >= 'A' && c<= 'Z') || c == '_') {
+        Color.append(1,c);
+        Pos++;
+        if (Pos >= Sectn.length())
+          break;
+        c = Sectn.at(Pos);
+      }
+      // Autos Section need to be given a different name from function frame. 
+      if (IsAutosSection)
+        SectionName = PAN::getAutosSectionForColor(Color);
+      else
+        SectionName = Color;
+    }
+  }
+  return SectionName;
+}
+
 const MCSection *
 PIC16TargetObjectFile::getBSSSectionForGlobal(const GlobalVariable *GV) const {
   assert(GV->hasInitializer() && "This global doesn't need space");
diff --git a/lib/Target/PIC16/PIC16TargetObjectFile.h b/lib/Target/PIC16/PIC16TargetObjectFile.h
index 4676b3c..a8f4c63 100644
--- a/lib/Target/PIC16/PIC16TargetObjectFile.h
+++ b/lib/Target/PIC16/PIC16TargetObjectFile.h
@@ -12,6 +12,7 @@
 
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Function.h"
 #include <vector>
 #include <string>
 
@@ -84,6 +85,9 @@
     // If the current function is cloned then create the new autos section
     // also. 
     void createClonedSectionForAutos(const std::string &SecName);
+    std::string getNameForFunctFrame(const Function *F, 
+                                     bool IsAutosSection = false); 
+
   private:
     std::string getSectionNameForSym(const std::string &Sym) const;