diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 95276b1..d22d467 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -699,6 +699,56 @@
   }
 }
 
+bool BitcodeReader::ParseMetadata() {
+  unsigned NextValueNo = ValueList.size();
+
+  if (Stream.EnterSubBlock(bitc::METADATA_BLOCK_ID))
+    return Error("Malformed block record");
+  
+  SmallVector<uint64_t, 64> Record;
+  
+  // Read all the records.
+  while (1) {
+    unsigned Code = Stream.ReadCode();
+    if (Code == bitc::END_BLOCK) {
+      if (Stream.ReadBlockEnd())
+        return Error("Error at end of PARAMATTR block");
+      return false;
+    }
+    
+    if (Code == bitc::ENTER_SUBBLOCK) {
+      // No known subblocks, always skip them.
+      Stream.ReadSubBlockID();
+      if (Stream.SkipBlock())
+        return Error("Malformed block record");
+      continue;
+    }
+    
+    if (Code == bitc::DEFINE_ABBREV) {
+      Stream.ReadAbbrevRecord();
+      continue;
+    }
+    
+    // Read a record.
+    Record.clear();
+    switch (Stream.ReadRecord(Code, Record)) {
+    default:  // Default behavior: ignore.
+      break;
+    case bitc::METADATA_STRING: {
+      unsigned MDStringLength = Record.size();
+      SmallString<8> String;
+      String.resize(MDStringLength);
+      for (unsigned i = 0; i != MDStringLength; ++i)
+        String[i] = Record[i];
+      Value *V = 
+        Context.getMDString(String.c_str(), String.c_str() + MDStringLength);
+      ValueList.AssignValue(V, NextValueNo++);
+      break;
+    }
+    }
+  }
+}
+
 /// DecodeSignRotatedValue - Decode a signed value stored with the sign bit in
 /// the LSB for dense VBR encoding.
 static uint64_t DecodeSignRotatedValue(uint64_t V) {
@@ -1028,15 +1078,6 @@
                          AsmStr, ConstrStr, HasSideEffects);
       break;
     }
-    case bitc::CST_CODE_MDSTRING: {
-      unsigned MDStringLength = Record.size();
-      SmallString<8> String;
-      String.resize(MDStringLength);
-      for (unsigned i = 0; i != MDStringLength; ++i)
-        String[i] = Record[i];
-      V = Context.getMDString(String.c_str(), String.c_str() + MDStringLength);
-      break;
-    }
     case bitc::CST_CODE_MDNODE: {
       if (Record.empty() || Record.size() % 2 == 1)
         return Error("Invalid CST_MDNODE record");
@@ -1171,6 +1212,10 @@
         if (ParseConstants() || ResolveGlobalAndAliasInits())
           return true;
         break;
+      case bitc::METADATA_BLOCK_ID:
+        if (ParseMetadata())
+          return true;
+        break;
       case bitc::FUNCTION_BLOCK_ID:
         // If this is the first function body we've seen, reverse the
         // FunctionsWithBodies list.
diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index bbbe4ec..77dabde 100644
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -210,6 +210,7 @@
   bool RememberAndSkipFunctionBody();
   bool ParseFunctionBody(Function *F);
   bool ResolveGlobalAndAliasInits();
+  bool ParseMetadata();
 };
   
 } // End llvm namespace
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index d245e5bc..467762e 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -473,6 +473,42 @@
   return Flags;
 }
 
+ static void WriteModuleMetadata(const ValueEnumerator &VE,
+                                 BitstreamWriter &Stream) {
+   const ValueEnumerator::ValueList &Vals = VE.getValues();
+   bool StartedMetadataBlock = false;
+   unsigned MDSAbbrev = 0;
+   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
+     if (const MDString *MDS = dyn_cast<MDString>(Vals[i].first)) {
+       if (!StartedMetadataBlock)  {
+        Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
+
+         // Abbrev for CST_CODE_STRING.
+         BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+         Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
+        Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+         Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
+         MDSAbbrev = Stream.EmitAbbrev(Abbv);
+         StartedMetadataBlock = true;
+       }
+
+      SmallVector<unsigned, 64> StrVals;
+      StrVals.clear();
+       // Code: [strchar x N]
+       const char *StrBegin = MDS->begin();
+       for (unsigned i = 0, e = MDS->size(); i != e; ++i)
+        StrVals.push_back(StrBegin[i]);
+    
+       // Emit the finished record.
+      Stream.EmitRecord(bitc::METADATA_STRING, StrVals, MDSAbbrev);
+     }
+   }
+
+   if (StartedMetadataBlock)
+     Stream.ExitBlock();    
+}
+
+
 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
                            const ValueEnumerator &VE,
                            BitstreamWriter &Stream, bool isGlobal) {
@@ -484,8 +520,6 @@
   unsigned String8Abbrev = 0;
   unsigned CString7Abbrev = 0;
   unsigned CString6Abbrev = 0;
-  unsigned MDString8Abbrev = 0;
-  unsigned MDString6Abbrev = 0;
   // If this is a constant pool for the module, emit module-specific abbrevs.
   if (isGlobal) {
     // Abbrev for CST_CODE_AGGREGATE.
@@ -513,19 +547,6 @@
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
     CString6Abbrev = Stream.EmitAbbrev(Abbv);
-
-    // Abbrev for CST_CODE_MDSTRING.
-    Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_MDSTRING));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
-    MDString8Abbrev = Stream.EmitAbbrev(Abbv);
-    // Abbrev for CST_CODE_MDSTRING.
-    Abbv = new BitCodeAbbrev();
-    Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_MDSTRING));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
-    MDString6Abbrev = Stream.EmitAbbrev(Abbv);
   }  
   
   SmallVector<uint64_t, 64> Record;
@@ -534,6 +555,8 @@
   const Type *LastTy = 0;
   for (unsigned i = FirstVal; i != LastVal; ++i) {
     const Value *V = Vals[i].first;
+    if (isa<MDString>(V))
+      continue;
     // If we need to switch types, do so now.
     if (V->getType() != LastTy) {
       LastTy = V->getType();
@@ -713,16 +736,6 @@
         Record.push_back(CE->getPredicate());
         break;
       }
-    } else if (const MDString *S = dyn_cast<MDString>(C)) {
-      Code = bitc::CST_CODE_MDSTRING;
-      AbbrevToUse = MDString6Abbrev;
-      for (unsigned i = 0, e = S->size(); i != e; ++i) {
-        char V = S->begin()[i];
-        Record.push_back(V);
-
-        if (!BitCodeAbbrevOp::isChar6(V))
-          AbbrevToUse = MDString8Abbrev;
-      }
     } else if (const MDNode *N = dyn_cast<MDNode>(C)) {
       Code = bitc::CST_CODE_MDNODE;
       for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
@@ -1328,7 +1341,10 @@
   // Emit top-level description of module, including target triple, inline asm,
   // descriptors for global variables, and function prototype info.
   WriteModuleInfo(M, VE, Stream);
-  
+
+  // Emit metadata.
+  WriteModuleMetadata(VE, Stream);
+
   // Emit constants.
   WriteModuleConstants(VE, Stream);
   
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index 32b2819..a31a492 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -259,10 +259,14 @@
       EnumerateOperandType(C->getOperand(i));
 
     if (const MDNode *N = dyn_cast<MDNode>(V)) {
-      for (unsigned i = 0, e = N->getNumElements(); i != e; ++i)
-        EnumerateOperandType(N->getElement(i));
+      for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
+        Value *Elem = N->getElement(i);
+        if (Elem)
+          EnumerateOperandType(Elem);
+      }
     }
-  }
+  } else if (const MDString *MDS = dyn_cast<MDString>(V))
+    EnumerateValue(V);
 }
 
 void ValueEnumerator::EnumerateAttributes(const AttrListPtr &PAL) {