Index: cfe/trunk/include/clang/Frontend/FrontendActions.h
===================================================================
--- cfe/trunk/include/clang/Frontend/FrontendActions.h
+++ cfe/trunk/include/clang/Frontend/FrontendActions.h
@@ -139,6 +139,12 @@
                                                  StringRef InFile) override;
 };
 
+class GenerateInterfaceIfsExpV1Action : public GenerateInterfaceStubAction {
+protected:
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
+                                                 StringRef InFile) override;
+};
+
 class GenerateModuleFromModuleMapAction : public GenerateModuleAction {
 private:
   bool BeginSourceFileAction(CompilerInstance &CI) override;
Index: cfe/trunk/include/clang/Frontend/FrontendOptions.h
===================================================================
--- cfe/trunk/include/clang/Frontend/FrontendOptions.h
+++ cfe/trunk/include/clang/Frontend/FrontendOptions.h
@@ -92,6 +92,7 @@
   /// Generate Interface Stub Files.
   GenerateInterfaceYAMLExpV1,
   GenerateInterfaceTBEExpV1,
+  GenerateInterfaceIfsExpV1,
 
   /// Only execute frontend initialization.
   InitOnly,
Index: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp
@@ -3638,12 +3638,14 @@
                   : "")
               .Case("experimental-yaml-elf-v1", "experimental-yaml-elf-v1")
               .Case("experimental-tapi-elf-v1", "experimental-tapi-elf-v1")
+              .Case("experimental-ifs-v1", "experimental-ifs-v1")
               .Default("");
 
       if (StubFormat.empty())
         D.Diag(diag::err_drv_invalid_value)
             << "Must specify a valid interface stub format type using "
             << "-interface-stub-version=<experimental-tapi-elf-v1 | "
+               "experimental-ifs-v1 | "
                "experimental-yaml-elf-v1>";
 
       CmdArgs.push_back("-emit-interface-stubs");
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -1737,11 +1737,14 @@
                     frontend::GenerateInterfaceYAMLExpV1)
               .Case("experimental-tapi-elf-v1",
                     frontend::GenerateInterfaceTBEExpV1)
+              .Case("experimental-ifs-v1",
+                    frontend::GenerateInterfaceIfsExpV1)
               .Default(llvm::None);
       if (!ProgramAction)
         Diags.Report(diag::err_drv_invalid_value)
             << "Must specify a valid interface stub format type using "
             << "-interface-stub-version=<experimental-tapi-elf-v1 | "
+               "experimental-ifs-v1 | "
                "experimental-yaml-elf-v1>";
       Opts.ProgramAction = *ProgramAction;
       break;
@@ -3185,6 +3188,7 @@
   case frontend::GeneratePCH:
   case frontend::GenerateInterfaceYAMLExpV1:
   case frontend::GenerateInterfaceTBEExpV1:
+  case frontend::GenerateInterfaceIfsExpV1:
   case frontend::ParseSyntaxOnly:
   case frontend::ModuleFileInfo:
   case frontend::VerifyPCH:
Index: cfe/trunk/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
===================================================================
--- cfe/trunk/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
+++ cfe/trunk/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
@@ -354,9 +354,55 @@
       OS.flush();
     };
 
+    auto writeIfsV1 =
+        [this](const llvm::Triple &T, const MangledSymbols &Symbols,
+               const ASTContext &context, StringRef Format,
+               raw_ostream &OS) -> void {
+      OS << "--- !" << Format << "\n";
+      OS << "IfsVersion: 1.0\n";
+      OS << "Triple: " << T.str() << "\n";
+      OS << "ObjectFileFormat: " << "ELF" << "\n"; // TODO: For now, just ELF.
+      OS << "Symbols:\n";
+      for (const auto &E : Symbols) {
+        const MangledSymbol &Symbol = E.second;
+        for (auto Name : Symbol.Names) {
+          OS << "  "
+             << (Symbol.ParentName.empty() || Instance.getLangOpts().CPlusPlus
+                     ? ""
+                     : (Symbol.ParentName + "."))
+             << Name << ": { Type: ";
+          switch (Symbol.Type) {
+          default:
+            llvm_unreachable(
+                "clang -emit-iterface-stubs: Unexpected symbol type.");
+          case llvm::ELF::STT_NOTYPE:
+            OS << "NoType";
+            break;
+          case llvm::ELF::STT_OBJECT: {
+            auto VD = cast<ValueDecl>(E.first)->getType();
+            OS << "Object, Size: "
+               << context.getTypeSizeInChars(VD).getQuantity();
+            break;
+          }
+          case llvm::ELF::STT_FUNC:
+            OS << "Func";
+            break;
+          }
+          if (Symbol.Binding == llvm::ELF::STB_WEAK)
+            OS << ", Weak: true";
+          OS << " }\n";
+        }
+      }
+      OS << "...\n";
+      OS.flush();
+    };
+
     if (Format == "experimental-yaml-elf-v1")
       writeIfoYaml(Instance.getTarget().getTriple(), Symbols, context, Format,
                    *OS);
+    else if (Format == "experimental-ifs-v1")
+      writeIfsV1(Instance.getTarget().getTriple(), Symbols, context, Format,
+                 *OS);
     else
       writeIfoElfAbiYaml(Instance.getTarget().getTriple(), Symbols, context,
                          Format, *OS);
@@ -376,3 +422,10 @@
   return std::make_unique<InterfaceStubFunctionsConsumer>(
       CI, InFile, "experimental-tapi-elf-v1");
 }
+
+std::unique_ptr<ASTConsumer>
+GenerateInterfaceIfsExpV1Action::CreateASTConsumer(CompilerInstance &CI,
+                                                   StringRef InFile) {
+  return std::make_unique<InterfaceStubFunctionsConsumer>(
+      CI, InFile, "experimental-ifs-v1");
+}
Index: cfe/trunk/lib/FrontendTool/ExecuteCompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ cfe/trunk/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -68,6 +68,8 @@
     return std::make_unique<GenerateInterfaceYAMLExpV1Action>();
   case GenerateInterfaceTBEExpV1:
     return std::make_unique<GenerateInterfaceTBEExpV1Action>();
+  case GenerateInterfaceIfsExpV1:
+    return std::make_unique<GenerateInterfaceIfsExpV1Action>();
   case InitOnly:               return std::make_unique<InitOnlyAction>();
   case ParseSyntaxOnly:        return std::make_unique<SyntaxOnlyAction>();
   case ModuleFileInfo:         return std::make_unique<DumpModuleInfoAction>();