diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -409,8 +409,14 @@
     (void)enable_fp;                      \
   } while (0)
 
-constexpr u32 kInvalidTid = -1;
-constexpr u32 kMainTid = 0;
+// Internal thread identifier allocated by ThreadRegistry.
+typedef u32 Tid;
+constexpr Tid kInvalidTid = -1;
+constexpr Tid kMainTid = 0;
+
+// Stack depot stack identifier.
+typedef u32 StackID;
+const StackID kInvalidStackID = 0;
 
 }  // namespace __sanitizer
 
diff --git a/compiler-rt/lib/tsan/go/tsan_go.cpp b/compiler-rt/lib/tsan/go/tsan_go.cpp
--- a/compiler-rt/lib/tsan/go/tsan_go.cpp
+++ b/compiler-rt/lib/tsan/go/tsan_go.cpp
@@ -220,7 +220,7 @@
 void __tsan_go_start(ThreadState *parent, ThreadState **pthr, void *pc) {
   ThreadState *thr = AllocGoroutine();
   *pthr = thr;
-  int goid = ThreadCreate(parent, (uptr)pc, 0, true);
+  Tid goid = ThreadCreate(parent, (uptr)pc, 0, true);
   ThreadStart(thr, goid, 0, ThreadType::Regular);
 }
 
diff --git a/compiler-rt/lib/tsan/rtl/tsan_fd.h b/compiler-rt/lib/tsan/rtl/tsan_fd.h
--- a/compiler-rt/lib/tsan/rtl/tsan_fd.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_fd.h
@@ -53,7 +53,7 @@
 void FdSocketAccept(ThreadState *thr, uptr pc, int fd, int newfd);
 void FdSocketConnecting(ThreadState *thr, uptr pc, int fd);
 void FdSocketConnect(ThreadState *thr, uptr pc, int fd);
-bool FdLocation(uptr addr, int *fd, int *tid, u32 *stack);
+bool FdLocation(uptr addr, int *fd, Tid *tid, StackID *stack);
 void FdOnFork(ThreadState *thr, uptr pc);
 
 uptr File2addr(const char *path);
diff --git a/compiler-rt/lib/tsan/rtl/tsan_fd.cpp b/compiler-rt/lib/tsan/rtl/tsan_fd.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_fd.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_fd.cpp
@@ -26,8 +26,8 @@
 
 struct FdDesc {
   FdSync *sync;
-  int creation_tid;
-  u32 creation_stack;
+  Tid creation_tid;
+  StackID creation_stack;
 };
 
 struct FdContext {
@@ -140,7 +140,7 @@
   }
 }
 
-bool FdLocation(uptr addr, int *fd, int *tid, u32 *stack) {
+bool FdLocation(uptr addr, int *fd, Tid *tid, StackID *stack) {
   for (int l1 = 0; l1 < kTableSizeL1; l1++) {
     FdDesc *tab = (FdDesc*)atomic_load(&fdctx.tab[l1], memory_order_relaxed);
     if (tab == 0)
@@ -211,8 +211,8 @@
   MemoryResetRange(thr, pc, (uptr)d, 8);
   unref(thr, pc, d->sync);
   d->sync = 0;
-  d->creation_tid = 0;
-  d->creation_stack = 0;
+  d->creation_tid = kInvalidTid;
+  d->creation_stack = kInvalidStackID;
 }
 
 void FdFileCreate(ThreadState *thr, uptr pc, int fd) {
diff --git a/compiler-rt/lib/tsan/rtl/tsan_ignoreset.h b/compiler-rt/lib/tsan/rtl/tsan_ignoreset.h
--- a/compiler-rt/lib/tsan/rtl/tsan_ignoreset.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_ignoreset.h
@@ -22,14 +22,14 @@
   static const uptr kMaxSize = 16;
 
   IgnoreSet();
-  void Add(u32 stack_id);
+  void Add(StackID stack_id);
   void Reset();
   uptr Size() const;
-  u32 At(uptr i) const;
+  StackID At(uptr i) const;
 
  private:
   uptr size_;
-  u32 stacks_[kMaxSize];
+  StackID stacks_[kMaxSize];
 };
 
 }  // namespace __tsan
diff --git a/compiler-rt/lib/tsan/rtl/tsan_ignoreset.cpp b/compiler-rt/lib/tsan/rtl/tsan_ignoreset.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_ignoreset.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_ignoreset.cpp
@@ -19,7 +19,7 @@
     : size_() {
 }
 
-void IgnoreSet::Add(u32 stack_id) {
+void IgnoreSet::Add(StackID stack_id) {
   if (size_ == kMaxSize)
     return;
   for (uptr i = 0; i < size_; i++) {
@@ -37,7 +37,7 @@
   return size_;
 }
 
-u32 IgnoreSet::At(uptr i) const {
+StackID IgnoreSet::At(uptr i) const {
   CHECK_LT(i, size_);
   CHECK_LE(size_, kMaxSize);
   return stacks_[i];
diff --git a/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp b/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp
@@ -1010,8 +1010,8 @@
     ThreadIgnoreEnd(thr);
   }
   if (res == 0) {
-    int tid = ThreadCreate(thr, pc, *(uptr*)th, IsStateDetached(detached));
-    CHECK_NE(tid, 0);
+    Tid tid = ThreadCreate(thr, pc, *(uptr *)th, IsStateDetached(detached));
+    CHECK_NE(tid, kMainTid);
     // Synchronization on p.tid serves two purposes:
     // 1. ThreadCreate must finish before the new thread starts.
     //    Otherwise the new thread can call pthread_detach, but the pthread_t
@@ -1030,7 +1030,7 @@
 
 TSAN_INTERCEPTOR(int, pthread_join, void *th, void **ret) {
   SCOPED_INTERCEPTOR_RAW(pthread_join, th, ret);
-  int tid = ThreadConsumeTid(thr, pc, (uptr)th);
+  Tid tid = ThreadConsumeTid(thr, pc, (uptr)th);
   ThreadIgnoreBegin(thr, pc);
   int res = BLOCK_REAL(pthread_join)(th, ret);
   ThreadIgnoreEnd(thr);
@@ -1044,7 +1044,7 @@
 
 TSAN_INTERCEPTOR(int, pthread_detach, void *th) {
   SCOPED_INTERCEPTOR_RAW(pthread_detach, th);
-  int tid = ThreadConsumeTid(thr, pc, (uptr)th);
+  Tid tid = ThreadConsumeTid(thr, pc, (uptr)th);
   int res = REAL(pthread_detach)(th);
   if (res == 0) {
     ThreadDetach(thr, pc, tid);
@@ -1065,7 +1065,7 @@
 #if SANITIZER_LINUX
 TSAN_INTERCEPTOR(int, pthread_tryjoin_np, void *th, void **ret) {
   SCOPED_INTERCEPTOR_RAW(pthread_tryjoin_np, th, ret);
-  int tid = ThreadConsumeTid(thr, pc, (uptr)th);
+  Tid tid = ThreadConsumeTid(thr, pc, (uptr)th);
   ThreadIgnoreBegin(thr, pc);
   int res = REAL(pthread_tryjoin_np)(th, ret);
   ThreadIgnoreEnd(thr);
@@ -1079,7 +1079,7 @@
 TSAN_INTERCEPTOR(int, pthread_timedjoin_np, void *th, void **ret,
                  const struct timespec *abstime) {
   SCOPED_INTERCEPTOR_RAW(pthread_timedjoin_np, th, ret, abstime);
-  int tid = ThreadConsumeTid(thr, pc, (uptr)th);
+  Tid tid = ThreadConsumeTid(thr, pc, (uptr)th);
   ThreadIgnoreBegin(thr, pc);
   int res = BLOCK_REAL(pthread_timedjoin_np)(th, ret, abstime);
   ThreadIgnoreEnd(thr);
diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cpp b/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_mac.cpp
@@ -215,8 +215,8 @@
       Processor *proc = ProcCreate();
       ProcWire(proc, thr);
       ThreadState *parent_thread_state = nullptr;  // No parent.
-      int tid = ThreadCreate(parent_thread_state, 0, (uptr)thread, true);
-      CHECK_NE(tid, 0);
+      Tid tid = ThreadCreate(parent_thread_state, 0, (uptr)thread, true);
+      CHECK_NE(tid, kMainTid);
       ThreadStart(thr, tid, GetTid(), ThreadType::Worker);
     }
   } else if (event == PTHREAD_INTROSPECTION_THREAD_TERMINATE) {
diff --git a/compiler-rt/lib/tsan/rtl/tsan_report.h b/compiler-rt/lib/tsan/rtl/tsan_report.h
--- a/compiler-rt/lib/tsan/rtl/tsan_report.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_report.h
@@ -74,19 +74,19 @@
   uptr heap_chunk_start = 0;
   uptr heap_chunk_size = 0;
   uptr external_tag = 0;
-  int tid = kInvalidTid;
+  Tid tid = kInvalidTid;
   int fd = 0;
   bool suppressable = false;
   ReportStack *stack = nullptr;
 };
 
 struct ReportThread {
-  int id;
+  Tid id;
   tid_t os_id;
   bool running;
   ThreadType thread_type;
   char *name;
-  u32 parent_tid;
+  Tid parent_tid;
   ReportStack *stack;
 };
 
@@ -106,7 +106,7 @@
   Vector<ReportLocation*> locs;
   Vector<ReportMutex*> mutexes;
   Vector<ReportThread*> threads;
-  Vector<int> unique_tids;
+  Vector<Tid> unique_tids;
   ReportStack *sleep;
   int count;
 
diff --git a/compiler-rt/lib/tsan/rtl/tsan_report.cpp b/compiler-rt/lib/tsan/rtl/tsan_report.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_report.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_report.cpp
@@ -52,7 +52,7 @@
 #if !SANITIZER_GO
 
 const int kThreadBufSize = 32;
-const char *thread_name(char *buf, int tid) {
+const char *thread_name(char *buf, Tid tid) {
   if (tid == kMainTid)
     return "main thread";
   internal_snprintf(buf, kThreadBufSize, "thread T%d", tid);
@@ -378,7 +378,7 @@
 
 #else  // #if !SANITIZER_GO
 
-const u32 kMainGoroutineId = 1;
+const Tid kMainGoroutineId = 1;
 
 void PrintStack(const ReportStack *ent) {
   if (ent == 0 || ent->frames == 0) {
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl.h b/compiler-rt/lib/tsan/rtl/tsan_rtl.h
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl.h
@@ -400,7 +400,7 @@
   Vector<JmpBuf> jmp_bufs;
   int ignore_interceptors;
 #endif
-  const u32 tid;
+  const Tid tid;
   const int unique_id;
   bool in_symbolizer;
   bool in_ignored_lib;
@@ -428,7 +428,7 @@
   ThreadSignalContext *signal_ctx;
 
 #if !SANITIZER_GO
-  u32 last_sleep_stack_id;
+  StackID last_sleep_stack_id;
   ThreadClock last_sleep_clock;
 #endif
 
@@ -438,7 +438,7 @@
 
   const ReportDesc *current_report;
 
-  explicit ThreadState(Context *ctx, u32 tid, int unique_id, u64 epoch,
+  explicit ThreadState(Context *ctx, Tid tid, int unique_id, u64 epoch,
                        unsigned reuse_count, uptr stk_addr, uptr stk_size,
                        uptr tls_addr, uptr tls_size);
 };
@@ -469,10 +469,10 @@
 
 class ThreadContext final : public ThreadContextBase {
  public:
-  explicit ThreadContext(int tid);
+  explicit ThreadContext(Tid tid);
   ~ThreadContext();
   ThreadState *thr;
-  u32 creation_stack_id;
+  StackID creation_stack_id;
   SyncClock sync;
   // Epoch at which the thread had started.
   // If we see an event from the thread stamped by an older epoch,
@@ -575,12 +575,12 @@
                        const MutexSet *mset);
   void AddStack(StackTrace stack, bool suppressable = false);
   void AddThread(const ThreadContext *tctx, bool suppressable = false);
-  void AddThread(int unique_tid, bool suppressable = false);
-  void AddUniqueTid(int unique_tid);
+  void AddThread(Tid unique_tid, bool suppressable = false);
+  void AddUniqueTid(Tid unique_tid);
   void AddMutex(const SyncVar *s);
   u64 AddMutex(u64 id);
   void AddLocation(uptr addr, uptr size);
-  void AddSleep(u32 stack_id);
+  void AddSleep(StackID stack_id);
   void SetCount(int count);
 
   const ReportDesc *GetReport() const;
@@ -612,7 +612,7 @@
 
 bool ShouldReport(ThreadState *thr, ReportType typ);
 ThreadContext *IsThreadStackOrTls(uptr addr, bool *is_stack);
-void RestoreStack(int tid, const u64 epoch, VarSizeStackTrace *stk,
+void RestoreStack(Tid tid, const u64 epoch, VarSizeStackTrace *stk,
                   MutexSet *mset, uptr *tag = nullptr);
 
 // The stack could look like:
@@ -678,8 +678,8 @@
 # define DPrintf2(...)
 #endif
 
-u32 CurrentStackId(ThreadState *thr, uptr pc);
-ReportStack *SymbolizeStackId(u32 stack_id);
+StackID CurrentStackId(ThreadState *thr, uptr pc);
+ReportStack *SymbolizeStackId(StackID stack_id);
 void PrintCurrentStack(ThreadState *thr, uptr pc);
 void PrintCurrentStackSlow(uptr pc);  // uses libunwind
 MBlock *JavaHeapBlock(uptr addr, uptr *start);
@@ -742,18 +742,18 @@
 void FuncEntry(ThreadState *thr, uptr pc);
 void FuncExit(ThreadState *thr);
 
-int ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached);
-void ThreadStart(ThreadState *thr, int tid, tid_t os_id,
+Tid ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached);
+void ThreadStart(ThreadState *thr, Tid tid, tid_t os_id,
                  ThreadType thread_type);
 void ThreadFinish(ThreadState *thr);
-int ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid);
-void ThreadJoin(ThreadState *thr, uptr pc, int tid);
-void ThreadDetach(ThreadState *thr, uptr pc, int tid);
+Tid ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid);
+void ThreadJoin(ThreadState *thr, uptr pc, Tid tid);
+void ThreadDetach(ThreadState *thr, uptr pc, Tid tid);
 void ThreadFinalize(ThreadState *thr);
 void ThreadSetName(ThreadState *thr, const char *name);
 int ThreadCount(ThreadState *thr);
 void ProcessPendingSignals(ThreadState *thr);
-void ThreadNotJoined(ThreadState *thr, uptr pc, int tid, uptr uid);
+void ThreadNotJoined(ThreadState *thr, uptr pc, Tid tid, uptr uid);
 
 Processor *ProcCreate();
 void ProcDestroy(Processor *proc);
@@ -818,7 +818,7 @@
 uptr TraceTopPC(ThreadState *thr);
 uptr TraceSize();
 uptr TraceParts();
-Trace *ThreadTrace(int tid);
+Trace *ThreadTrace(Tid tid);
 
 extern "C" void __tsan_trace_switch();
 void ALWAYS_INLINE TraceAddEvent(ThreadState *thr, FastState fs,
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl.cpp
@@ -77,7 +77,7 @@
 }
 #endif
 
-static ThreadContextBase *CreateThreadContext(u32 tid) {
+static ThreadContextBase *CreateThreadContext(Tid tid) {
   // Map thread trace when context is created.
   char name[50];
   internal_snprintf(name, sizeof(name), "trace %u", tid);
@@ -126,7 +126,7 @@
 }
 
 // The objects are allocated in TLS, so one may rely on zero-initialization.
-ThreadState::ThreadState(Context *ctx, u32 tid, int unique_id, u64 epoch,
+ThreadState::ThreadState(Context *ctx, Tid tid, int unique_id, u64 epoch,
                          unsigned reuse_count, uptr stk_addr, uptr stk_size,
                          uptr tls_addr, uptr tls_size)
     : fast_state(tid, epoch)
@@ -438,8 +438,8 @@
           (int)internal_getpid());
 
   // Initialize thread 0.
-  int tid = ThreadCreate(thr, 0, 0, true);
-  CHECK_EQ(tid, 0);
+  Tid tid = ThreadCreate(thr, 0, 0, true);
+  CHECK_EQ(tid, kMainTid);
   ThreadStart(thr, tid, GetTid(), ThreadType::Regular);
 #if TSAN_CONTAINS_UBSAN
   __ubsan::InitAsPlugin();
@@ -581,9 +581,9 @@
 }
 #endif
 
-u32 CurrentStackId(ThreadState *thr, uptr pc) {
+StackID CurrentStackId(ThreadState *thr, uptr pc) {
   if (!thr->is_inited)  // May happen during bootstrap.
-    return 0;
+    return kInvalidStackID;
   if (pc != 0) {
 #if !SANITIZER_GO
     DCHECK_LT(thr->shadow_stack_pos, thr->shadow_stack_end);
@@ -594,7 +594,7 @@
     thr->shadow_stack_pos[0] = pc;
     thr->shadow_stack_pos++;
   }
-  u32 id = StackDepotPut(
+  StackID id = StackDepotPut(
       StackTrace(thr->shadow_stack, thr->shadow_stack_pos - thr->shadow_stack));
   if (pc != 0)
     thr->shadow_stack_pos--;
@@ -617,9 +617,7 @@
   thr->nomalloc--;
 }
 
-Trace *ThreadTrace(int tid) {
-  return (Trace*)GetThreadTraceHeader(tid);
-}
+Trace *ThreadTrace(Tid tid) { return (Trace *)GetThreadTraceHeader(tid); }
 
 uptr TraceTopPC(ThreadState *thr) {
   Event *events = (Event*)GetThreadTrace(thr->tid);
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
@@ -35,7 +35,7 @@
     DDCallback::lt = thr->dd_lt;
   }
 
-  u32 Unwind() override { return CurrentStackId(thr, pc); }
+  StackID Unwind() override { return CurrentStackId(thr, pc); }
   int UniqueTid() override { return thr->unique_id; }
 };
 
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_report.cpp
@@ -195,7 +195,7 @@
   }
 }
 
-void ScopedReportBase::AddUniqueTid(int unique_tid) {
+void ScopedReportBase::AddUniqueTid(Tid unique_tid) {
   rep_->unique_tids.PushBack(unique_tid);
 }
 
@@ -224,14 +224,14 @@
   return tctx->unique_id == (u32)unique_id;
 }
 
-static ThreadContext *FindThreadByUidLocked(int unique_id) {
+static ThreadContext *FindThreadByUidLocked(Tid unique_id) {
   ctx->thread_registry.CheckLocked();
   return static_cast<ThreadContext *>(
       ctx->thread_registry.FindThreadContextLocked(
           FindThreadByUidLockedCallback, &unique_id));
 }
 
-static ThreadContext *FindThreadByTidLocked(int tid) {
+static ThreadContext *FindThreadByTidLocked(Tid tid) {
   ctx->thread_registry.CheckLocked();
   return static_cast<ThreadContext *>(
       ctx->thread_registry.GetThreadLocked(tid));
@@ -262,7 +262,7 @@
 }
 #endif
 
-void ScopedReportBase::AddThread(int unique_tid, bool suppressable) {
+void ScopedReportBase::AddThread(Tid unique_tid, bool suppressable) {
 #if !SANITIZER_GO
   if (const ThreadContext *tctx = FindThreadByUidLocked(unique_tid))
     AddThread(tctx, suppressable);
@@ -319,8 +319,8 @@
     return;
 #if !SANITIZER_GO
   int fd = -1;
-  int creat_tid = kInvalidTid;
-  u32 creat_stack = 0;
+  Tid creat_tid = kInvalidTid;
+  StackID creat_stack = 0;
   if (FdLocation(addr, &fd, &creat_tid, &creat_stack)) {
     auto *loc = New<ReportLocation>();
     loc->type = ReportLocationFD;
@@ -374,7 +374,7 @@
 }
 
 #if !SANITIZER_GO
-void ScopedReportBase::AddSleep(u32 stack_id) {
+void ScopedReportBase::AddSleep(StackID stack_id) {
   rep_->sleep = SymbolizeStackId(stack_id);
 }
 #endif
@@ -388,7 +388,7 @@
 
 ScopedReport::~ScopedReport() {}
 
-void RestoreStack(int tid, const u64 epoch, VarSizeStackTrace *stk,
+void RestoreStack(Tid tid, const u64 epoch, VarSizeStackTrace *stk,
                   MutexSet *mset, uptr *tag) {
   // This function restores stack trace and mutex set for the thread/epoch.
   // It does so by getting stack trace and mutex set at the beginning of
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
@@ -21,13 +21,8 @@
 
 // ThreadContext implementation.
 
-ThreadContext::ThreadContext(int tid)
-  : ThreadContextBase(tid)
-  , thr()
-  , sync()
-  , epoch0()
-  , epoch1() {
-}
+ThreadContext::ThreadContext(Tid tid)
+    : ThreadContextBase(tid), thr(), sync(), epoch0(), epoch1() {}
 
 #if !SANITIZER_GO
 ThreadContext::~ThreadContext() {
@@ -223,15 +218,15 @@
   return (int)result;
 }
 
-int ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached) {
+Tid ThreadCreate(ThreadState *thr, uptr pc, uptr uid, bool detached) {
   OnCreatedArgs args = { thr, pc };
   u32 parent_tid = thr ? thr->tid : kInvalidTid;  // No parent for GCD workers.
-  int tid = ctx->thread_registry.CreateThread(uid, detached, parent_tid, &args);
+  Tid tid = ctx->thread_registry.CreateThread(uid, detached, parent_tid, &args);
   DPrintf("#%d: ThreadCreate tid=%d uid=%zu\n", parent_tid, tid, uid);
   return tid;
 }
 
-void ThreadStart(ThreadState *thr, int tid, tid_t os_id,
+void ThreadStart(ThreadState *thr, Tid tid, tid_t os_id,
                  ThreadType thread_type) {
   uptr stk_addr = 0;
   uptr stk_size = 0;
@@ -299,28 +294,28 @@
   return false;
 }
 
-int ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid) {
+Tid ThreadConsumeTid(ThreadState *thr, uptr pc, uptr uid) {
   ConsumeThreadContext findCtx = {uid, nullptr};
   ctx->thread_registry.FindThread(ConsumeThreadByUid, &findCtx);
-  int tid = findCtx.tctx ? findCtx.tctx->tid : kInvalidTid;
+  Tid tid = findCtx.tctx ? findCtx.tctx->tid : kInvalidTid;
   DPrintf("#%d: ThreadTid uid=%zu tid=%d\n", thr->tid, uid, tid);
   return tid;
 }
 
-void ThreadJoin(ThreadState *thr, uptr pc, int tid) {
+void ThreadJoin(ThreadState *thr, uptr pc, Tid tid) {
   CHECK_GT(tid, 0);
   CHECK_LT(tid, kMaxTid);
   DPrintf("#%d: ThreadJoin tid=%d\n", thr->tid, tid);
   ctx->thread_registry.JoinThread(tid, thr);
 }
 
-void ThreadDetach(ThreadState *thr, uptr pc, int tid) {
+void ThreadDetach(ThreadState *thr, uptr pc, Tid tid) {
   CHECK_GT(tid, 0);
   CHECK_LT(tid, kMaxTid);
   ctx->thread_registry.DetachThread(tid, thr);
 }
 
-void ThreadNotJoined(ThreadState *thr, uptr pc, int tid, uptr uid) {
+void ThreadNotJoined(ThreadState *thr, uptr pc, Tid tid, uptr uid) {
   CHECK_GT(tid, 0);
   CHECK_LT(tid, kMaxTid);
   ctx->thread_registry.SetThreadUserId(tid, uid);
@@ -421,7 +416,7 @@
   void *mem = Alloc(sizeof(ThreadState));
   ThreadState *fiber = static_cast<ThreadState *>(mem);
   internal_memset(fiber, 0, sizeof(*fiber));
-  int tid = ThreadCreate(thr, pc, 0, true);
+  Tid tid = ThreadCreate(thr, pc, 0, true);
   FiberSwitchImpl(thr, fiber);
   ThreadStart(fiber, tid, 0, ThreadType::Fiber);
   FiberSwitchImpl(fiber, thr);
diff --git a/compiler-rt/lib/tsan/rtl/tsan_sync.h b/compiler-rt/lib/tsan/rtl/tsan_sync.h
--- a/compiler-rt/lib/tsan/rtl/tsan_sync.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_sync.h
@@ -52,8 +52,8 @@
   uptr addr;  // overwritten by DenseSlabAlloc freelist
   Mutex mtx;
   u64 uid;  // Globally unique id.
-  u32 creation_stack_id;
-  u32 owner_tid;  // Set only by exclusive owners.
+  StackID creation_stack_id;
+  Tid owner_tid;  // Set only by exclusive owners.
   u64 last_lock;
   int recursion;
   atomic_uint32_t flags;