diff --git a/include/clang/Basic/IdentifierTable.h b/include/clang/Basic/IdentifierTable.h
index 2cb68b3..66c5dee 100644
--- a/include/clang/Basic/IdentifierTable.h
+++ b/include/clang/Basic/IdentifierTable.h
@@ -254,6 +254,35 @@
   }
 };
 
+/// \brief An iterator that walks over all of the known identifiers
+/// in the lookup table.
+///
+/// Since this iterator uses an abstract interface via virtual
+/// functions, it uses an object-oriented interface rather than the
+/// more standard C++ STL iterator interface. In this OO-style
+/// iteration, the single function \c Next() provides dereference,
+/// advance, and end-of-sequence checking in a single
+/// operation. Subclasses of this iterator type will provide the
+/// actual functionality.
+class IdentifierIterator {
+private:
+  IdentifierIterator(const IdentifierIterator&); // Do not implement
+  IdentifierIterator &operator=(const IdentifierIterator&); // Do not implement
+
+protected:
+  IdentifierIterator() { }
+  
+public:
+  virtual ~IdentifierIterator();
+
+  /// \brief Retrieve the next string in the identifier table and
+  /// advances the iterator for the following string.
+  ///
+  /// \returns The next string in the identifier table. If there is
+  /// no such string, returns an empty \c llvm::StringRef.
+  virtual llvm::StringRef Next() = 0;
+};
+
 /// IdentifierInfoLookup - An abstract class used by IdentifierTable that
 ///  provides an interface for performing lookups from strings
 /// (const char *) to IdentiferInfo objects.
@@ -266,6 +295,18 @@
   ///  of a reference.  If the pointer is NULL then the IdentifierInfo cannot
   ///  be found.
   virtual IdentifierInfo* get(llvm::StringRef Name) = 0;
+
+  /// \brief Retrieve an iterator into the set of all identifiers
+  /// known to this identifier lookup source.
+  ///
+  /// This routine provides access to all of the identifiers known to
+  /// the identifier lookup, allowing access to the contents of the
+  /// identifiers without introducing the overhead of constructing
+  /// IdentifierInfo objects for each.
+  ///
+  /// \returns A new iterator into the set of known identifiers. The
+  /// caller is responsible for deleting this iterator.
+  virtual IdentifierIterator *getIdentifiers() const;
 };
 
 /// \brief An abstract class used to resolve numerical identifier
@@ -304,6 +345,11 @@
     ExternalLookup = IILookup;
   }
 
+  /// \brief Retrieve the external identifier lookup object, if any.
+  IdentifierInfoLookup *getExternalIdentifierLookup() const {
+    return ExternalLookup;
+  }
+  
   llvm::BumpPtrAllocator& getAllocator() {
     return HashTable.getAllocator();
   }
diff --git a/include/clang/Basic/OnDiskHashTable.h b/include/clang/Basic/OnDiskHashTable.h
index 8909e47..30bf39e 100644
--- a/include/clang/Basic/OnDiskHashTable.h
+++ b/include/clang/Basic/OnDiskHashTable.h
@@ -334,6 +334,70 @@
 
   iterator end() const { return iterator(); }
 
+  /// \brief Iterates over all of the keys in the table.
+  class key_iterator {
+    const unsigned char* Ptr;
+    unsigned NumItemsInBucketLeft;
+    unsigned NumEntriesLeft;
+    Info *InfoObj;
+  public:
+    typedef external_key_type value_type;
+
+    key_iterator(const unsigned char* const Ptr, unsigned NumEntries,
+                  Info *InfoObj)
+      : Ptr(Ptr), NumItemsInBucketLeft(0), NumEntriesLeft(NumEntries),
+        InfoObj(InfoObj) { }
+    key_iterator()
+      : Ptr(0), NumItemsInBucketLeft(0), NumEntriesLeft(0), InfoObj(0) { }
+
+    friend bool operator==(const key_iterator &X, const key_iterator &Y) {
+      return X.NumEntriesLeft == Y.NumEntriesLeft;
+    }
+    friend bool operator!=(const key_iterator& X, const key_iterator &Y) {
+      return X.NumEntriesLeft != Y.NumEntriesLeft;
+    }
+    
+    key_iterator& operator++() {  // Preincrement
+      if (!NumItemsInBucketLeft) {
+        // 'Items' starts with a 16-bit unsigned integer representing the
+        // number of items in this bucket.
+        NumItemsInBucketLeft = io::ReadUnalignedLE16(Ptr);
+      }
+      Ptr += 4; // Skip the hash.
+      // Determine the length of the key and the data.
+      const std::pair<unsigned, unsigned>& L = Info::ReadKeyDataLength(Ptr);
+      Ptr += L.first + L.second;
+      assert(NumItemsInBucketLeft);
+      --NumItemsInBucketLeft;
+      assert(NumEntriesLeft);
+      --NumEntriesLeft;
+      return *this;
+    }
+    key_iterator operator++(int) {  // Postincrement
+      key_iterator tmp = *this; ++*this; return tmp;
+    }
+
+    value_type operator*() const {
+      const unsigned char* LocalPtr = Ptr;
+      if (!NumItemsInBucketLeft)
+        LocalPtr += 2; // number of items in bucket
+      LocalPtr += 4; // Skip the hash.
+
+      // Determine the length of the key and the data.
+      const std::pair<unsigned, unsigned>& L
+        = Info::ReadKeyDataLength(LocalPtr);
+
+      // Read the key.
+      const internal_key_type& Key = InfoObj->ReadKey(LocalPtr, L.first);
+      return InfoObj->GetExternalKey(Key);
+    }
+  };
+
+  key_iterator key_begin() {
+    return key_iterator(Base + 4, getNumEntries(), &InfoObj);
+  }
+  key_iterator key_end() { return key_iterator(); }
+
   /// \brief Iterates over all the entries in the table, returning
   /// a key/data pair.
   class item_iterator {
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index f275c76..01ccc06 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -47,6 +47,7 @@
 class AddrLabelExpr;
 class ASTConsumer;
 class ASTContext;
+class ASTIdentifierIterator;
 class Attr;
 class Decl;
 class DeclContext;
@@ -180,6 +181,7 @@
   friend class PCHValidator;
   friend class ASTDeclReader;
   friend class ASTStmtReader;
+  friend class ASTIdentifierIterator;
   friend class ASTIdentifierLookupTrait;
   friend class TypeLocReader;
 private:
@@ -969,6 +971,10 @@
     return get(Name.begin(), Name.end());
   }
 
+  /// \brief Retrieve an iterator into the set of all identifiers
+  /// in all loaded AST files.
+  virtual IdentifierIterator *getIdentifiers() const;
+
   /// \brief Load the contents of the global method pool for a given
   /// selector.
   ///
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index bd30c68..4ea6ced 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -44,8 +44,24 @@
 // IdentifierTable Implementation
 //===----------------------------------------------------------------------===//
 
+IdentifierIterator::~IdentifierIterator() { }
+
 IdentifierInfoLookup::~IdentifierInfoLookup() {}
 
+namespace {
+  /// \brief A simple identifier lookup iterator that represents an
+  /// empty sequence of identifiers.
+  class EmptyLookupIterator : public IdentifierIterator
+  {
+  public:
+    virtual llvm::StringRef Next() { return llvm::StringRef(); }
+  };
+}
+
+IdentifierIterator *IdentifierInfoLookup::getIdentifiers() const {
+  return new EmptyLookupIterator();
+}
+
 ExternalIdentifierLookup::~ExternalIdentifierLookup() {}
 
 IdentifierTable::IdentifierTable(const LangOptions &LangOpts,
diff --git a/lib/Sema/SemaExprObjC.cpp b/lib/Sema/SemaExprObjC.cpp
index 055edd9..1a90a2a 100644
--- a/lib/Sema/SemaExprObjC.cpp
+++ b/lib/Sema/SemaExprObjC.cpp
@@ -557,9 +557,10 @@
   ReceiverType = ParsedType();
 
   // If the identifier is "super" and there is no trailing dot, we're
-  // messaging super.
-  if (IsSuper && !HasTrailingDot && S->isInObjcMethodScope())
-    return ObjCSuperMessage;
+  // messaging super. If the identifier is "super" and there is a
+  // trailing dot, it's an instance message.
+  if (IsSuper && S->isInObjcMethodScope())
+    return HasTrailingDot? ObjCInstanceMessage : ObjCSuperMessage;
   
   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
   LookupName(Result, S);
@@ -568,14 +569,15 @@
   case LookupResult::NotFound:
     // Normal name lookup didn't find anything. If we're in an
     // Objective-C method, look for ivars. If we find one, we're done!
-    // FIXME: This is a hack. Ivar lookup should be part of normal lookup.
+    // FIXME: This is a hack. Ivar lookup should be part of normal
+    // lookup.
     if (ObjCMethodDecl *Method = getCurMethodDecl()) {
       ObjCInterfaceDecl *ClassDeclared;
       if (Method->getClassInterface()->lookupInstanceVariable(Name, 
                                                               ClassDeclared))
         return ObjCInstanceMessage;
     }
-      
+  
     // Break out; we'll perform typo correction below.
     break;
 
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index b363e57..f12ac22 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -2694,6 +2694,7 @@
       BestEditDistance((std::numeric_limits<unsigned>::max)()) { }
 
   virtual void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, bool InBaseClass);
+  void FoundName(llvm::StringRef Name);
   void addKeywordResult(ASTContext &Context, llvm::StringRef Keyword);
 
   typedef llvm::StringMap<bool, llvm::BumpPtrAllocator>::iterator iterator;
@@ -2721,10 +2722,17 @@
   if (!Name)
     return;
 
+  FoundName(Name->getName());
+}
+
+void TypoCorrectionConsumer::FoundName(llvm::StringRef Name) {
   // Compute the edit distance between the typo and the name of this
   // entity. If this edit distance is not worse than the best edit
   // distance we've seen so far, add it to the list of results.
-  unsigned ED = Typo.edit_distance(Name->getName());
+  unsigned ED = Typo.edit_distance(Name);
+  if (ED == 0)
+    return;
+  
   if (ED < BestEditDistance) {
     // This result is better than any we've seen before; clear out
     // the previous results.
@@ -2735,12 +2743,12 @@
     // ignore it.
     return;
   }
-
+  
   // Add this name to the list of results. By not assigning a value, we
   // keep the current value if we've seen this name before (either as a
   // keyword or as a declaration), or get the default value (not a keyword)
   // if we haven't seen it before.
-  (void)BestResults[Name->getName()];
+  (void)BestResults[Name];  
 }
 
 void TypoCorrectionConsumer::addKeywordResult(ASTContext &Context, 
@@ -2842,7 +2850,25 @@
     
     LookupVisibleDecls(DC, Res.getLookupKind(), Consumer);
   } else {
-    LookupVisibleDecls(S, Res.getLookupKind(), Consumer);
+    // For unqualified lookup, look through all of the names that we have
+    // seen in this translation unit.
+    for (IdentifierTable::iterator I = Context.Idents.begin(), 
+                                IEnd = Context.Idents.end();
+         I != IEnd; ++I)
+      Consumer.FoundName(I->getKey());
+    
+    // Walk through identifiers in external identifier sources.
+    if (IdentifierInfoLookup *External
+                              = Context.Idents.getExternalIdentifierLookup()) {
+      IdentifierIterator *Iter = External->getIdentifiers();
+      do {
+        llvm::StringRef Name = Iter->Next();
+        if (Name.empty())
+          break;
+
+        Consumer.FoundName(Name);
+      } while (true);
+    }
   }
 
   // Add context-dependent keywords.
@@ -3017,7 +3043,7 @@
   // Make sure that the user typed at least 3 characters for each correction 
   // made. Otherwise, we don't even both looking at the results.
   unsigned ED = Consumer.getBestEditDistance();
-  if (ED == 0 || (Typo->getName().size() / ED) < 3)
+  if (ED > 0 && Typo->getName().size() / ED < 3)
     return DeclarationName();
 
   // Weed out any names that could not be found by name lookup.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 2002ccd..0f7486f 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -603,6 +603,10 @@
   static const internal_key_type&
   GetInternalKey(const external_key_type& x) { return x; }
 
+  // This hopefully will just get inlined and removed by the optimizer.
+  static const external_key_type&
+  GetExternalKey(const internal_key_type& x) { return x; }
+
   static std::pair<unsigned, unsigned>
   ReadKeyDataLength(const unsigned char*& d) {
     using namespace clang::io;
@@ -3571,6 +3575,64 @@
   return 0;
 }
 
+namespace clang {
+  /// \brief An identifier-lookup iterator that enumerates all of the
+  /// identifiers stored within a set of AST files.
+  class ASTIdentifierIterator : public IdentifierIterator {
+    /// \brief The AST reader whose identifiers are being enumerated.
+    const ASTReader &Reader;
+
+    /// \brief The current index into the chain of AST files stored in
+    /// the AST reader.
+    unsigned Index;
+
+    /// \brief The current position within the identifier lookup table
+    /// of the current AST file.
+    ASTIdentifierLookupTable::key_iterator Current;
+
+    /// \brief The end position within the identifier lookup table of
+    /// the current AST file.
+    ASTIdentifierLookupTable::key_iterator End;
+
+  public:
+    explicit ASTIdentifierIterator(const ASTReader &Reader);
+
+    virtual llvm::StringRef Next();
+  };
+}
+
+ASTIdentifierIterator::ASTIdentifierIterator(const ASTReader &Reader)
+  : Reader(Reader), Index(Reader.Chain.size() - 1) {
+  ASTIdentifierLookupTable *IdTable
+    = (ASTIdentifierLookupTable *)Reader.Chain[Index]->IdentifierLookupTable;
+  Current = IdTable->key_begin();
+  End = IdTable->key_end();
+}
+
+llvm::StringRef ASTIdentifierIterator::Next() {
+  while (Current == End) {
+    // If we have exhausted all of our AST files, we're done.
+    if (Index == 0)
+      return llvm::StringRef();
+
+    --Index;
+    ASTIdentifierLookupTable *IdTable
+      = (ASTIdentifierLookupTable *)Reader.Chain[Index]->IdentifierLookupTable;
+    Current = IdTable->key_begin();
+    End = IdTable->key_end();
+  }
+
+  // We have any identifiers remaining in the current AST file; return
+  // the next one.
+  std::pair<const char*, unsigned> Key = *Current;
+  ++Current;
+  return llvm::StringRef(Key.first, Key.second);
+}
+
+IdentifierIterator *ASTReader::getIdentifiers() const {
+  return new ASTIdentifierIterator(*this);
+}
+
 std::pair<ObjCMethodList, ObjCMethodList>
 ASTReader::ReadMethodPool(Selector Sel) {
   // Find this selector in a hash table. We want to find the most recent entry.
diff --git a/test/PCH/Inputs/typo.h b/test/PCH/Inputs/typo.h
new file mode 100644
index 0000000..63b553b
--- /dev/null
+++ b/test/PCH/Inputs/typo.h
@@ -0,0 +1,6 @@
+
+
+@interface NSString
++ (id)alloc;
+@end
+
diff --git a/test/PCH/typo.m b/test/PCH/typo.m
new file mode 100644
index 0000000..c6f0275
--- /dev/null
+++ b/test/PCH/typo.m
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -x objective-c-header -emit-pch -o %t %S/Inputs/typo.h
+// RUN: %clang_cc1 -include-pch %t -verify %s
+// In header: expected-note{{declared here}}
+void f() {
+  [NSstring alloc]; // expected-error{{unknown receiver 'NSstring'; did you mean 'NSString'?}}
+}
diff --git a/test/SemaObjC/synth-provisional-ivars.m b/test/SemaObjC/synth-provisional-ivars.m
index 973c771..8ad2233 100644
--- a/test/SemaObjC/synth-provisional-ivars.m
+++ b/test/SemaObjC/synth-provisional-ivars.m
@@ -18,7 +18,7 @@
 @end
 
 @implementation I
-- (int) Meth { return PROP; }	// expected-note {{'PROP' declared here}}
+- (int) Meth { return PROP; }
 
 @dynamic PROP1;
 - (int) Meth1 { return PROP1; }  // expected-error {{use of undeclared identifier 'PROP1'}}