Index: lib/Driver/Compilation.cpp
===================================================================
--- lib/Driver/Compilation.cpp
+++ lib/Driver/Compilation.cpp
@@ -22,6 +22,8 @@
 using namespace clang;
 using namespace llvm::opt;
 
+int main(int argc_, const char **argv_);
+
 Compilation::Compilation(const Driver &D, const ToolChain &_DefaultToolChain,
                          InputArgList *_Args, DerivedArgList *_TranslatedArgs)
     : TheDriver(D), DefaultToolChain(_DefaultToolChain), Args(_Args),
@@ -197,9 +199,19 @@
   if (const Command *C = dyn_cast<Command>(&J)) {
     if (!InputsOk(*C, FailingCommands))
       return;
-    const Command *FailingCommand = nullptr;
-    if (int Res = ExecuteCommand(*C, FailingCommand))
-      FailingCommands.push_back(std::make_pair(Res, FailingCommand));
+    if (C->getExecutable() == getDriver().getClangProgramPath()) {
+      ArgStringList Args = C->getArguments();
+Args.insert(Args.begin(), C->getExecutable());
+//fprintf(stderr, "in-process\n");
+// XXX response files
+      main(Args.size(), const_cast<const char**>(&Args[0]));
+// XXX this breaks /fallback
+exit(0);
+    } else {
+      const Command *FailingCommand = nullptr;
+      if (int Res = ExecuteCommand(*C, FailingCommand))
+        FailingCommands.push_back(std::make_pair(Res, FailingCommand));
+    }
   } else {
     const JobList *Jobs = cast<JobList>(&J);
     for (const auto &Job : *Jobs)
Index: tools/driver/driver.cpp
===================================================================
--- tools/driver/driver.cpp
+++ tools/driver/driver.cpp
@@ -382,14 +382,19 @@
   if (llvm::sys::Process::FixupStandardFileDescriptors())
     return 1;
 
+//for (int i = 0; i < argc_; ++i) fprintf(stderr, " %s", argv_[i]);
+//fprintf(stderr, "\n");
+
   SmallVector<const char *, 256> argv;
   llvm::SpecificBumpPtrAllocator<char> ArgAllocator;
-  std::error_code EC = llvm::sys::Process::GetArgumentVector(
-      argv, llvm::makeArrayRef(argv_, argc_), ArgAllocator);
-  if (EC) {
-    llvm::errs() << "error: couldn't get arguments: " << EC.message() << '\n';
-    return 1;
-  }
+// XXX :-(
+  //std::error_code EC = llvm::sys::Process::GetArgumentVector(
+      //argv, llvm::makeArrayRef(argv_, argc_), ArgAllocator);
+for (int i = 0; i < argc_; ++i) argv.push_back(argv_[i]);
+  //if (EC) {
+    //llvm::errs() << "error: couldn't get arguments: " << EC.message() << '\n';
+    //return 1;
+  //}
 
   std::set<std::string> SavedStrings;
   StringSetSaver Saver(SavedStrings);