diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index d538d6e..3e08d99 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1410,9 +1410,18 @@
 
 template <typename T>
 void ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
-  enum RedeclKind { FirstInFile, PointsToPrevious };
+  enum RedeclKind { OnlyDeclaration = 0, FirstInFile, PointsToPrevious };
   RedeclKind Kind = (RedeclKind)Record[Idx++];
   
+  // If this is the only known declaration of this entity, this module file
+  // has no additional redeclaration information. However, other module
+  // files might have redeclarations.
+  if (Kind == OnlyDeclaration) {
+    if (Reader.PendingDeclChainsKnown.insert(ThisDeclID))
+      Reader.PendingDeclChains.push_back(ThisDeclID);
+    return;
+  }
+  
   // Read the first declaration ID, and note that we need to reconstruct
   // the redeclaration chain once we hit the top level.
   DeclID FirstDeclID = ReadDeclID(Record, Idx);
@@ -1422,6 +1431,9 @@
   T *FirstDecl = cast_or_null<T>(Reader.GetDecl(FirstDeclID));
 
   switch (Kind) {
+  case OnlyDeclaration:
+    llvm_unreachable("only declaration handled above");
+      
   case FirstInFile:
     if (FirstDecl != D)
       D->RedeclLink = typename Redeclarable<T>::PreviousDeclLink(FirstDecl);
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 4e9a315..bb4359a 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -126,30 +126,6 @@
   };
 }
 
-static bool isFirstDeclInFile(Decl *D) {
-  // FIXME: There must be a better way to abstract Redeclarable<T> into a 
-  // more-general "redeclarable type".
-  if (TagDecl *Tag = dyn_cast<TagDecl>(D))
-    return !Tag->getPreviousDeclaration() ||
-           Tag->getPreviousDeclaration()->isFromASTFile();
-  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
-    return !FD->getPreviousDeclaration() ||
-           FD->getPreviousDeclaration()->isFromASTFile();
-  if (VarDecl *VD = dyn_cast<VarDecl>(D))
-    return !VD->getPreviousDeclaration() ||
-           VD->getPreviousDeclaration()->isFromASTFile();
-  if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D))
-    return !TD->getPreviousDeclaration() ||
-           TD->getPreviousDeclaration()->isFromASTFile();
-  if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(D))
-    return !ID->getPreviousDeclaration() ||
-            ID->getPreviousDeclaration()->isFromASTFile();
-  
-  RedeclarableTemplateDecl *RTD = cast<RedeclarableTemplateDecl>(D);
-  return !RTD->getPreviousDeclaration() ||
-          RTD->getPreviousDeclaration()->isFromASTFile();  
-}
-
 void ASTDeclWriter::Visit(Decl *D) {
   DeclVisitor<ASTDeclWriter>::Visit(D);
 
@@ -212,7 +188,7 @@
   if (!D->hasAttrs() &&
       !D->isImplicit() &&
       !D->isUsed(false) &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -262,7 +238,7 @@
       !D->isImplicit() &&
       !D->isUsed(false) &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -286,7 +262,7 @@
       !D->isImplicit() &&
       !D->isUsed(false) &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -732,7 +708,7 @@
       !D->isModulePrivate() &&
       D->getDeclName().getNameKind() == DeclarationName::Identifier &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->hasCXXDirectInitializer() &&
       D->getInit() == 0 &&
       !isa<ParmVarDecl>(D) &&
@@ -1298,7 +1274,13 @@
 
 template <typename T>
 void ASTDeclWriter::VisitRedeclarable(Redeclarable<T> *D) {
-  enum { FirstInFile, PointsToPrevious };
+  enum { OnlyDeclaration = 0, FirstInFile, PointsToPrevious };
+  if (D->RedeclLink.getPointer() == D) {
+    // This is the only declaration.
+    Record.push_back(OnlyDeclaration);
+    return;
+  }
+  
   T *First = D->getFirstDeclaration();
   if (!D->getPreviousDeclaration() ||
       D->getPreviousDeclaration()->isFromASTFile()) {
@@ -1399,8 +1381,7 @@
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_ENUM));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1447,8 +1428,7 @@
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_RECORD));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1489,8 +1469,7 @@
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_PARM_VAR));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1540,8 +1519,7 @@
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_TYPEDEF));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1569,8 +1547,7 @@
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_VAR));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
diff --git a/test/Modules/Inputs/redecl-merge-bottom.h b/test/Modules/Inputs/redecl-merge-bottom.h
index e45e0de..198bde3 100644
--- a/test/Modules/Inputs/redecl-merge-bottom.h
+++ b/test/Modules/Inputs/redecl-merge-bottom.h
@@ -1,4 +1,7 @@
 __import_module__ redecl_merge_left;
 __import_module__ redecl_merge_right;
 
+@class B;
+
 @class A;
+
diff --git a/test/Modules/Inputs/redecl-merge-left.h b/test/Modules/Inputs/redecl-merge-left.h
index 0858922..048b3e6 100644
--- a/test/Modules/Inputs/redecl-merge-left.h
+++ b/test/Modules/Inputs/redecl-merge-left.h
@@ -4,4 +4,8 @@
 
 @class A;
 
+@interface B
+@end
+
 @class A;
+
diff --git a/test/Modules/Inputs/redecl-merge-right.h b/test/Modules/Inputs/redecl-merge-right.h
index 266146c..d8fd45f 100644
--- a/test/Modules/Inputs/redecl-merge-right.h
+++ b/test/Modules/Inputs/redecl-merge-right.h
@@ -7,3 +7,5 @@
 - (Super*)init;
 @end
 
+@class B;
+
diff --git a/test/Modules/Inputs/redecl-merge-top.h b/test/Modules/Inputs/redecl-merge-top.h
index 886436c..68dae50 100644
--- a/test/Modules/Inputs/redecl-merge-top.h
+++ b/test/Modules/Inputs/redecl-merge-top.h
@@ -3,3 +3,5 @@
 @class A;
 
 @class A;
+
+@class B;
diff --git a/test/Modules/redecl-merge.m b/test/Modules/redecl-merge.m
index d62d504..fe25044 100644
--- a/test/Modules/redecl-merge.m
+++ b/test/Modules/redecl-merge.m
@@ -14,8 +14,13 @@
 
 @class A;
 
+@class B;
+
 __import_module__ redecl_merge_bottom;
 
+@implementation B
+@end
+
 void g(A *a) {
   [a init];
 }