diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 604b23143e9d..92dcc7d70327 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2053,8 +2053,24 @@ bool ASTReader::ReadASTBlock(ModuleFile &F) {
       break;
 
     case SPECIAL_TYPES:
-      for (unsigned I = 0, N = Record.size(); I != N; ++I)
-        SpecialTypes.push_back(getGlobalTypeID(F, Record[I]));
+      if (SpecialTypes.empty()) {
+        for (unsigned I = 0, N = Record.size(); I != N; ++I)
+          SpecialTypes.push_back(getGlobalTypeID(F, Record[I]));
+        break;
+      }
+
+      if (SpecialTypes.size() != Record.size()) {
+        Error("invalid special-types record");
+        return true;
+      }
+
+      for (unsigned I = 0, N = Record.size(); I != N; ++I) {
+        serialization::TypeID ID = getGlobalTypeID(F, Record[I]);
+        if (!SpecialTypes[I])
+          SpecialTypes[I] = ID;
+        // FIXME: If ID && SpecialTypes[I] != ID, do we need a separate
+        // merge step?
+      }
       break;
 
     case STATISTICS:
diff --git a/clang/test/Modules/Inputs/module.map b/clang/test/Modules/Inputs/module.map
index 5ec595c9e1b8..55496fa35a22 100644
--- a/clang/test/Modules/Inputs/module.map
+++ b/clang/test/Modules/Inputs/module.map
@@ -155,3 +155,7 @@ module autolink {
     link framework "autolink_framework"
   }
 }
+
+module weird_objc {
+  header "weird_objc.h"
+}
diff --git a/clang/test/Modules/Inputs/weird_objc.h b/clang/test/Modules/Inputs/weird_objc.h
new file mode 100644
index 000000000000..8acaf746e855
--- /dev/null
+++ b/clang/test/Modules/Inputs/weird_objc.h
@@ -0,0 +1 @@
+typedef struct objc_object { void *super; int wibble; } *id;
diff --git a/clang/test/Modules/objc_redef.m b/clang/test/Modules/objc_redef.m
new file mode 100644
index 000000000000..13a5b1d9cc07
--- /dev/null
+++ b/clang/test/Modules/objc_redef.m
@@ -0,0 +1,13 @@
+@import redeclarations_left;
+@import weird_objc;
+
+int test(id x) {
+  return x->wibble;
+}
+
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -x objective-c -fmodule-cache-path %t -emit-module -fmodule-name=redeclarations_left %S/Inputs/module.map
+// RUN: %clang_cc1 -fmodules -x objective-c -fmodule-cache-path %t -emit-module -fmodule-name=weird_objc %S/Inputs/module.map
+// RUN: %clang_cc1 -fmodules -fmodule-cache-path %t %s -verify
+// expected-no-diagnostics
+