diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 79dc441..a175ce5 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -475,6 +475,8 @@
   HelpText<"Disable validation of precompiled headers">;
 def dump_deserialized_pch_decls : Flag<"-dump-deserialized-decls">,
   HelpText<"Dump declarations that are deserialized from PCH, for testing">;
+def error_on_deserialized_pch_decl : Separate<"-error-on-deserialized-decl">,
+  HelpText<"Emit error if a specific declaration is deserialized from PCH, for testing">;
 def fshort_wchar : Flag<"-fshort-wchar">,
   HelpText<"Force wchar_t to be a short unsigned int">;
 def fshort_enums : Flag<"-fshort-enums">,
diff --git a/include/clang/Frontend/PreprocessorOptions.h b/include/clang/Frontend/PreprocessorOptions.h
index 34b49e1..2a540b6 100644
--- a/include/clang/Frontend/PreprocessorOptions.h
+++ b/include/clang/Frontend/PreprocessorOptions.h
@@ -15,6 +15,7 @@
 #include <string>
 #include <utility>
 #include <vector>
+#include <set>
 
 namespace llvm {
   class MemoryBuffer;
@@ -50,6 +51,10 @@
   /// \brief Dump declarations that are deserialized from PCH, for testing.
   bool DumpDeserializedPCHDecls;
 
+  /// \brief This is a set of names for decls that we do not want to be
+  /// deserialized, and we emit an error if they are; for testing purposes.
+  std::set<std::string> DeserializedPCHDeclsToErrorOn;
+
   /// \brief If non-zero, the implicit PCH include is actually a precompiled
   /// preamble that covers this number of bytes in the main source file.
   ///
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 8f0cb08..3a928a5 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1409,7 +1409,13 @@
   Opts.UsePredefines = !Args.hasArg(OPT_undef);
   Opts.DetailedRecord = Args.hasArg(OPT_detailed_preprocessing_record);
   Opts.DisablePCHValidation = Args.hasArg(OPT_fno_validate_pch);
+
   Opts.DumpDeserializedPCHDecls = Args.hasArg(OPT_dump_deserialized_pch_decls);
+  for (arg_iterator it = Args.filtered_begin(OPT_error_on_deserialized_pch_decl),
+         ie = Args.filtered_end(); it != ie; ++it) {
+    const Arg *A = *it;
+    Opts.DeserializedPCHDeclsToErrorOn.insert(A->getValue(Args));
+  }
 
   if (const Arg *A = Args.getLastArg(OPT_preamble_bytes_EQ)) {
     llvm::StringRef Value(A->getValue(Args));
diff --git a/lib/Frontend/FrontendAction.cpp b/lib/Frontend/FrontendAction.cpp
index 429b009..819aa52 100644
--- a/lib/Frontend/FrontendAction.cpp
+++ b/lib/Frontend/FrontendAction.cpp
@@ -51,6 +51,41 @@
                                    MacroDefinition *MD) {}
 };
 
+  /// \brief Checks deserialized declarations and emits error if a name
+  /// matches one given in command-line using -error-on-deserialized-decl.
+  class DeserializedDeclsChecker : public ASTDeserializationListener {
+    ASTContext &Ctx;
+    std::set<std::string> NamesToCheck;
+    ASTDeserializationListener *Previous;
+
+  public:
+    DeserializedDeclsChecker(ASTContext &Ctx,
+                             const std::set<std::string> &NamesToCheck, 
+                             ASTDeserializationListener *Previous)
+      : Ctx(Ctx), NamesToCheck(NamesToCheck), Previous(Previous) { }
+
+    virtual void DeclRead(serialization::DeclID ID, const Decl *D) {
+      if (const NamedDecl *ND = dyn_cast<NamedDecl>(D))
+        if (NamesToCheck.find(ND->getNameAsString()) != NamesToCheck.end()) {
+          unsigned DiagID
+            = Ctx.getDiagnostics().getCustomDiagID(Diagnostic::Error,
+                                                   "%0 was deserialized");
+          Ctx.getDiagnostics().Report(Ctx.getFullLoc(D->getLocation()), DiagID)
+              << ND->getNameAsString();
+        }
+
+      if (Previous)
+        Previous->DeclRead(ID, D);
+    }
+
+    virtual void SetReader(ASTReader *Reader) {}
+    virtual void IdentifierRead(serialization::IdentID ID, IdentifierInfo *II) {}
+    virtual void TypeRead(serialization::TypeIdx Idx, QualType T) {}
+    virtual void SelectorRead(serialization::SelectorID iD, Selector Sel) {}
+    virtual void MacroDefinitionRead(serialization::MacroID,
+                                     MacroDefinition *MD) {}
+};
+
 } // end anonymous namespace
 
 FrontendAction::FrontendAction() : Instance(0) {}
@@ -154,6 +189,10 @@
                   Consumer->GetASTDeserializationListener() : 0;
       if (CI.getPreprocessorOpts().DumpDeserializedPCHDecls)
         DeserialListener = new DeserializedDeclsDumper(DeserialListener);
+      if (!CI.getPreprocessorOpts().DeserializedPCHDeclsToErrorOn.empty())
+        DeserialListener = new DeserializedDeclsChecker(CI.getASTContext(),
+                         CI.getPreprocessorOpts().DeserializedPCHDeclsToErrorOn,
+                                                        DeserialListener);
       CI.createPCHExternalASTSource(
                                 CI.getPreprocessorOpts().ImplicitPCHInclude,
                                 CI.getPreprocessorOpts().DisablePCHValidation,