diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 419e84e..b778a60 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -447,7 +447,7 @@
 
   void setAnonymousNamespace(NamespaceDecl *D) {
     assert(!D || D->isAnonymousNamespace());
-    assert(!D || D->getParent() == this);
+    assert(!D || D->getParent()->getRedeclContext() == this);
     getOriginalNamespace()->OrigOrAnonNamespace.setPointer(D);
   }
 
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 3d4e4cd..52eff19 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1741,10 +1741,15 @@
 
     case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE: {
       NamespaceDecl *Anon = cast<NamespaceDecl>(Reader.GetDecl(Record[Idx++]));
-      if (TranslationUnitDecl *TU = dyn_cast<TranslationUnitDecl>(D))
-        TU->setAnonymousNamespace(Anon);
-      else
-        cast<NamespaceDecl>(D)->OrigOrAnonNamespace.setPointer(Anon);
+      // Guard against these being loaded out of original order. Don't use
+      // getNextNamespace(), since it tries to access the context and can't in
+      // the middle of deserialization.
+      if (!Anon->NextNamespace) {
+        if (TranslationUnitDecl *TU = dyn_cast<TranslationUnitDecl>(D))
+          TU->setAnonymousNamespace(Anon);
+        else
+          cast<NamespaceDecl>(D)->OrigOrAnonNamespace.setPointer(Anon);
+      }
       break;
     }
     }
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index db72be3..df83f2f 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -708,11 +708,13 @@
     }
   }
 
-  if (Writer.hasChain() && D->isOriginalNamespace() &&
-      D->isAnonymousNamespace()) {
-    // This is an original anonymous namespace. If its parent is in a previous
-    // PCH (or is the TU), mark that parent for update.
-    Decl *Parent = cast<Decl>(D->getParent()->getPrimaryContext());
+  if (Writer.hasChain() && D->isAnonymousNamespace() && !D->getNextNamespace()){
+    // This is a most recent reopening of the anonymous namespace. If its parent
+    // is in a previous PCH (or is the TU), mark that parent for update, because
+    // the original namespace always points to the latest re-opening of its
+    // anonymous namespace.
+    Decl *Parent = cast<Decl>(
+        D->getParent()->getRedeclContext()->getPrimaryContext());
     if (Parent->getPCHLevel() > 0) {
       ASTWriter::UpdateRecord &Record = Writer.DeclUpdates[Parent];
       Record.push_back(UPD_CXX_ADDED_ANONYMOUS_NAMESPACE);
diff --git a/test/PCH/chain-late-anonymous-namespace.cpp b/test/PCH/chain-late-anonymous-namespace.cpp
index 5369947..87205c6 100644
--- a/test/PCH/chain-late-anonymous-namespace.cpp
+++ b/test/PCH/chain-late-anonymous-namespace.cpp
@@ -6,6 +6,7 @@
 #define PASS1
 
 namespace ns {}
+namespace os {}
 
 #elif !defined(PASS2)
 #define PASS2
@@ -19,6 +20,16 @@
 namespace {
   extern int y;
 }
+namespace {
+}
+
+namespace os {
+  extern "C" {
+    namespace {
+      extern int z;
+    }
+  }
+}
 
 #else
 
@@ -38,4 +49,13 @@
   (void)y;
 }
 
+namespace os {
+  namespace {
+    int z;
+  }
+  void test() {
+    (void)z;
+  }
+}
+
 #endif