diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index a43d0d3..586002d 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -27,6 +27,7 @@
 #include "clang/Frontend/FrontendOptions.h"
 #include "clang/Frontend/Utils.h"
 #include "clang/Serialization/ASTReader.h"
+#include "clang/Serialization/ASTSerializationListener.h"
 #include "clang/Serialization/ASTWriter.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Preprocessor.h"
@@ -637,10 +638,11 @@
   }
 };
 
-class PrecompilePreambleConsumer : public PCHGenerator {
+class PrecompilePreambleConsumer : public PCHGenerator, 
+                                   public ASTSerializationListener {
   ASTUnit &Unit;
   std::vector<Decl *> TopLevelDecls;
-
+                                     
 public:
   PrecompilePreambleConsumer(ASTUnit &Unit,
                              const Preprocessor &PP, bool Chaining,
@@ -672,6 +674,15 @@
                                       getWriter().getDeclID(TopLevelDecls[I]));
     }
   }
+                                     
+  virtual void SerializedPreprocessedEntity(PreprocessedEntity *Entity,
+                                            uint64_t Offset) {
+    Unit.addPreprocessedEntityFromPreamble(Offset);
+  }
+                                     
+  virtual ASTSerializationListener *GetASTSerializationListener() {
+    return this;
+  }
 };
 
 class PrecompilePreambleAction : public ASTFrontendAction {
@@ -757,6 +768,7 @@
   
   // Clear out old caches and data.
   TopLevelDecls.clear();
+  PreprocessedEntities.clear();
   CleanTemporaryFiles();
   PreprocessedEntitiesByFile.clear();
 
@@ -765,6 +777,7 @@
                     StoredDiagnostics.begin() + NumStoredDiagnosticsFromDriver,
                             StoredDiagnostics.end());
     TopLevelDeclsInPreamble.clear();
+    PreprocessedEntitiesInPreamble.clear();
   }
 
   // Create a file manager object to provide access to and cache the filesystem.
@@ -1237,6 +1250,8 @@
                           StoredDiagnostics.end());
   TopLevelDecls.clear();
   TopLevelDeclsInPreamble.clear();
+  PreprocessedEntities.clear();
+  PreprocessedEntitiesInPreamble.clear();
   
   // Create a file manager object to provide access to and cache the filesystem.
   Clang.setFileManager(new FileManager(Clang.getFileSystemOpts()));
@@ -1269,6 +1284,8 @@
     llvm::sys::Path(FrontendOpts.OutputFile).eraseFromDisk();
     Preamble.clear();
     TopLevelDeclsInPreamble.clear();
+    PreprocessedEntities.clear();
+    PreprocessedEntitiesInPreamble.clear();
     PreambleRebuildCounter = DefaultPreambleRebuildInterval;
     PreprocessorOpts.eraseRemappedFile(
                                PreprocessorOpts.remapped_file_buffer_end() - 1);
@@ -1321,6 +1338,55 @@
   TopLevelDecls.insert(TopLevelDecls.begin(), Resolved.begin(), Resolved.end());
 }
 
+void ASTUnit::RealizePreprocessedEntitiesFromPreamble() {
+  if (!PP)
+    return;
+  
+  PreprocessingRecord *PPRec = PP->getPreprocessingRecord();
+  if (!PPRec)
+    return;
+  
+  ExternalPreprocessingRecordSource *External = PPRec->getExternalSource();
+  if (!External)
+    return;
+
+  for (unsigned I = 0, N = PreprocessedEntitiesInPreamble.size(); I != N; ++I) {
+    if (PreprocessedEntity *PE
+          = External->ReadPreprocessedEntity(PreprocessedEntitiesInPreamble[I]))
+      PreprocessedEntities.push_back(PE);
+  }
+  
+  if (PreprocessedEntities.empty())
+    return;
+  
+  PreprocessedEntities.insert(PreprocessedEntities.end(), 
+                              PPRec->begin(true), PPRec->end(true));
+}
+
+ASTUnit::pp_entity_iterator ASTUnit::pp_entity_begin() {
+  if (!PreprocessedEntitiesInPreamble.empty() &&
+      PreprocessedEntities.empty())
+    RealizePreprocessedEntitiesFromPreamble();
+  
+  if (PreprocessedEntities.empty())
+    if (PreprocessingRecord *PPRec = PP->getPreprocessingRecord())
+      return PPRec->begin(true);
+  
+  return PreprocessedEntities.begin();
+}
+
+ASTUnit::pp_entity_iterator ASTUnit::pp_entity_end() {
+  if (!PreprocessedEntitiesInPreamble.empty() &&
+      PreprocessedEntities.empty())
+    RealizePreprocessedEntitiesFromPreamble();
+  
+  if (PreprocessedEntities.empty())
+    if (PreprocessingRecord *PPRec = PP->getPreprocessingRecord())
+      return PPRec->end(true);
+  
+  return PreprocessedEntities.end();
+}
+
 unsigned ASTUnit::getMaxPCHLevel() const {
   if (!getOnlyLocalDecls())
     return Decl::MaxPCHLevel;