diff --git a/compiler-rt/lib/asan/asan_interceptors.cpp b/compiler-rt/lib/asan/asan_interceptors.cpp
--- a/compiler-rt/lib/asan/asan_interceptors.cpp
+++ b/compiler-rt/lib/asan/asan_interceptors.cpp
@@ -223,9 +223,8 @@
   auto self = GetThreadSelf();
   auto args = asanThreadArgRetval().GetArgs(self);
   t->ThreadStart(GetTid());
-  thread_return_t retval = t->RunThread();
+  thread_return_t retval = (*args.routine)(args.arg_retval);
   asanThreadArgRetval().Finish(self, retval);
-  CHECK_EQ(args.arg_retval, t->get_arg());
   return retval;
 }
 
@@ -243,8 +242,7 @@
   }();
 
   u32 current_tid = GetCurrentTidOrInvalid();
-  AsanThread *t =
-      AsanThread::Create(start_routine, arg, current_tid, &stack, detached);
+  AsanThread *t = AsanThread::Create(current_tid, &stack, detached);
 
   int result;
   {
diff --git a/compiler-rt/lib/asan/asan_mac.cpp b/compiler-rt/lib/asan/asan_mac.cpp
--- a/compiler-rt/lib/asan/asan_mac.cpp
+++ b/compiler-rt/lib/asan/asan_mac.cpp
@@ -154,8 +154,7 @@
 void asan_register_worker_thread(int parent_tid, StackTrace *stack) {
   AsanThread *t = GetCurrentThread();
   if (!t) {
-    t = AsanThread::Create(/* start_routine */ nullptr, /* arg */ nullptr,
-                           parent_tid, stack, /* detached */ true);
+    t = AsanThread::Create(parent_tid, stack, /* detached */ true);
     t->Init();
     asanThreadRegistry().StartThread(t->tid(), GetTid(), ThreadType::Worker,
                                      nullptr);
diff --git a/compiler-rt/lib/asan/asan_thread.h b/compiler-rt/lib/asan/asan_thread.h
--- a/compiler-rt/lib/asan/asan_thread.h
+++ b/compiler-rt/lib/asan/asan_thread.h
@@ -59,8 +59,14 @@
 // AsanThread are stored in TSD and destroyed when the thread dies.
 class AsanThread {
  public:
-  static AsanThread *Create(thread_callback_t start_routine, void *arg,
-                            u32 parent_tid, StackTrace *stack, bool detached);
+  template <typename T>
+  static AsanThread *Create(const T &data, u32 parent_tid, StackTrace *stack,
+                            bool detached) {
+    return Create(&data, sizeof(data), parent_tid, stack, detached);
+  }
+  static AsanThread *Create(u32 parent_tid, StackTrace *stack, bool detached) {
+    return Create(nullptr, 0, parent_tid, stack, detached);
+  }
   static void TSDDtor(void *tsd);
   void Destroy();
 
@@ -131,12 +137,18 @@
 
   void *extra_spill_area() { return &extra_spill_area_; }
 
-  void *get_arg() const { return arg_; }
+  template <typename T>
+  void GetStartData(T &data) const {
+    GetStartData(&data, sizeof(data));
+  }
 
  private:
   // NOTE: There is no AsanThread constructor. It is allocated
   // via mmap() and *must* be valid in zero-initialized state.
 
+  static AsanThread *Create(const void *start_data, uptr data_size,
+                            u32 parent_tid, StackTrace *stack, bool detached);
+
   void SetThreadStackAndTls(const InitOptions *options);
 
   void ClearShadowForThreadStackAndTLS();
@@ -148,9 +160,9 @@
   };
   StackBounds GetStackBounds() const;
 
+  void GetStartData(void *out, uptr out_size) const;
+
   AsanThreadContext *context_;
-  thread_callback_t start_routine_;
-  void *arg_;
 
   uptr stack_top_;
   uptr stack_bottom_;
@@ -169,6 +181,8 @@
   AsanStats stats_;
   bool unwinding_;
   uptr extra_spill_area_;
+
+  char start_data_[];
 };
 
 // Returns a single instance of registry.
diff --git a/compiler-rt/lib/asan/asan_thread.cpp b/compiler-rt/lib/asan/asan_thread.cpp
--- a/compiler-rt/lib/asan/asan_thread.cpp
+++ b/compiler-rt/lib/asan/asan_thread.cpp
@@ -91,20 +91,27 @@
 
 // AsanThread implementation.
 
-AsanThread *AsanThread::Create(thread_callback_t start_routine, void *arg,
+AsanThread *AsanThread::Create(const void *start_data, uptr data_size,
                                u32 parent_tid, StackTrace *stack,
                                bool detached) {
   uptr PageSize = GetPageSizeCached();
   uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
   AsanThread *thread = (AsanThread *)MmapOrDie(size, __func__);
-  thread->start_routine_ = start_routine;
-  thread->arg_ = arg;
+  if (data_size) {
+    uptr availible_size = (uptr)thread + size - (uptr)(thread->start_data_);
+    CHECK_LE(data_size, availible_size);
+    internal_memcpy(thread->start_data_, start_data, data_size);
+  }
   AsanThreadContext::CreateThreadContextArgs args = {thread, stack};
   asanThreadRegistry().CreateThread(0, detached, parent_tid, &args);
 
   return thread;
 }
 
+void AsanThread::GetStartData(void *out, uptr out_size) const {
+  internal_memcpy(out, start_data_, out_size);
+}
+
 void AsanThread::TSDDtor(void *tsd) {
   AsanThreadContext *context = (AsanThreadContext *)tsd;
   VReport(1, "T%d TSDDtor\n", context->tid);
@@ -281,11 +288,9 @@
     SetAlternateSignalStack();
 }
 
-thread_return_t AsanThread::RunThread() { return start_routine_(arg_); }
-
 AsanThread *CreateMainThread() {
   AsanThread *main_thread = AsanThread::Create(
-      /* start_routine */ nullptr, /* arg */ nullptr, /* parent_tid */ kMainTid,
+      /* parent_tid */ kMainTid,
       /* stack */ nullptr, /* detached */ true);
   SetCurrentThread(main_thread);
   main_thread->ThreadStart(internal_getpid());
diff --git a/compiler-rt/lib/asan/asan_win.cpp b/compiler-rt/lib/asan/asan_win.cpp
--- a/compiler-rt/lib/asan/asan_win.cpp
+++ b/compiler-rt/lib/asan/asan_win.cpp
@@ -131,11 +131,20 @@
 }
 #endif
 
+struct ThreadStartParams {
+  thread_callback_t start_routine;
+  void *arg;
+};
+
 static thread_return_t THREAD_CALLING_CONV asan_thread_start(void *arg) {
   AsanThread *t = (AsanThread *)arg;
   SetCurrentThread(t);
   t->ThreadStart(GetTid());
-  auto res = t->RunThread();
+
+  ThreadStartParams params;
+  t->GetStartData(params);
+
+  auto res = (*params.start_routine)(params.arg);
   t->Destroy();  // POSIX calls this from TSD destructor.
   return res;
 }
@@ -151,8 +160,8 @@
   // one.  This is a bandaid fix for PR22025.
   bool detached = false;  // FIXME: how can we determine it on Windows?
   u32 current_tid = GetCurrentTidOrInvalid();
-  AsanThread *t =
-      AsanThread::Create(start_routine, arg, current_tid, &stack, detached);
+  ThreadStartParams params = {start_routine, arg};
+  AsanThread *t = AsanThread::Create(params, current_tid, &stack, detached);
   return REAL(CreateThread)(security, stack_size, asan_thread_start, t,
                             thr_flags, tid);
 }