diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index f08b801..79dc441 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -473,6 +473,8 @@
   HelpText<"Disable generation of rtti information">;
 def fno_validate_pch : Flag<"-fno-validate-pch">,
   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 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 851c1f0..34b49e1 100644
--- a/include/clang/Frontend/PreprocessorOptions.h
+++ b/include/clang/Frontend/PreprocessorOptions.h
@@ -46,7 +46,10 @@
   /// \brief When true, disables most of the normal validation performed on
   /// precompiled headers.
   bool DisablePCHValidation;
-  
+
+  /// \brief Dump declarations that are deserialized from PCH, for testing.
+  bool DumpDeserializedPCHDecls;
+
   /// \brief If non-zero, the implicit PCH include is actually a precompiled
   /// preamble that covers this number of bytes in the main source file.
   ///
@@ -118,6 +121,7 @@
 public:
   PreprocessorOptions() : UsePredefines(true), DetailedRecord(false),
                           DisablePCHValidation(false),
+                          DumpDeserializedPCHDecls(false),
                           PrecompiledPreambleBytes(0, true),
                           RetainRemappedFileBuffers(false) { }
 
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index e3ba54c..8f0cb08 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1409,6 +1409,7 @@
   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);
 
   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 b244c5c..429b009 100644
--- a/lib/Frontend/FrontendAction.cpp
+++ b/lib/Frontend/FrontendAction.cpp
@@ -16,12 +16,43 @@
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Parse/ParseAST.h"
+#include "clang/Serialization/ASTDeserializationListener.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace clang;
 
+namespace {
+
+/// \brief Dumps deserialized declarations.
+class DeserializedDeclsDumper : public ASTDeserializationListener {
+  ASTDeserializationListener *Previous;
+
+public:
+  DeserializedDeclsDumper(ASTDeserializationListener *Previous)
+    : Previous(Previous) { }
+
+  virtual void DeclRead(serialization::DeclID ID, const Decl *D) {
+    llvm::outs() << "PCH DECL: " << D->getDeclKindName();
+    if (const NamedDecl *ND = dyn_cast<NamedDecl>(D))
+      llvm::outs() << " - " << ND->getNameAsString();
+    llvm::outs() << "\n";
+
+    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) {}
 
 FrontendAction::~FrontendAction() {}
@@ -118,11 +149,15 @@
     /// Use PCH?
     if (!CI.getPreprocessorOpts().ImplicitPCHInclude.empty()) {
       assert(hasPCHSupport() && "This action does not have PCH support!");
+      ASTDeserializationListener *DeserialListener
+          = CI.getInvocation().getFrontendOpts().ChainedPCH ?
+                  Consumer->GetASTDeserializationListener() : 0;
+      if (CI.getPreprocessorOpts().DumpDeserializedPCHDecls)
+        DeserialListener = new DeserializedDeclsDumper(DeserialListener);
       CI.createPCHExternalASTSource(
                                 CI.getPreprocessorOpts().ImplicitPCHInclude,
                                 CI.getPreprocessorOpts().DisablePCHValidation,
-                                CI.getInvocation().getFrontendOpts().ChainedPCH?
-                                 Consumer->GetASTDeserializationListener() : 0);
+                                DeserialListener);
       if (!CI.getASTContext().getExternalSource())
         goto failure;
     }