diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index 1d6c536..bcf5384 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -32,6 +32,7 @@
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitcode/BitstreamReader.h"
@@ -397,9 +398,11 @@
   /// preprocessing record.
   unsigned NumPreallocatedPreprocessingEntities;
   
-  /// \brief All the modules that loaded this one. Can contain NULL for
-  /// directly loaded modules.
-  SmallVector<Module *, 1> Loaders;
+  /// \brief List of modules which depend on this module
+  llvm::SetVector<Module *> ImportedBy;
+  
+  /// \brief List of modules which this module depends on
+  llvm::SetVector<Module *> Imports;
 };
 
 /// \brief The manager for modules loaded by the ASTReader.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index f5c2ec3..d8f6c6a 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1380,9 +1380,10 @@
 SourceLocation ASTReader::getImportLocation(Module *F) {
   if (F->ImportLoc.isValid())
     return F->ImportLoc;
+  
   // Otherwise we have a PCH. It's considered to be "imported" at the first
   // location of its includer.
-  if (F->Loaders.empty() || !F->Loaders[0]) {
+  if (F->ImportedBy.empty() || !F->ImportedBy[0]) {
     // Main file is the importer. We assume that it is the first entry in the
     // entry table. We can't ask the manager, because at the time of PCH loading
     // the main file entry doesn't exist yet.
@@ -1390,7 +1391,8 @@
     // offsets 0 and 1.
     return SourceLocation::getFromRawEncoding(2U);
   }
-  return F->Loaders[0]->FirstLoc;
+  //return F->Loaders[0]->FirstLoc;
+  return F->ImportedBy[0]->FirstLoc;
 }
 
 /// ReadBlockAbbrevs - Enter a subblock of the specified BlockID with the
@@ -5466,8 +5468,11 @@
   const FileEntry *Entry = FileMgr.getFile(FileName);
   Modules[Entry] = Current;
 
-  Current->Loaders.push_back(Prev);
-
+  if (Prev) {
+    Current->ImportedBy.insert(Prev);
+    Prev->Imports.insert(Current);
+  }
+  
   return *Current;
 }