diff --git a/compiler-rt/lib/tsan/rtl/tsan_sync.cpp b/compiler-rt/lib/tsan/rtl/tsan_sync.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_sync.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_sync.cpp
@@ -194,18 +194,16 @@
   u32 *meta = MemToMeta(addr);
   u32 idx0 = *meta;
   u32 myidx = 0;
-  SyncVar *mys = 0;
+  SyncVar *mys = nullptr;
   for (;;) {
     u32 idx = idx0;
     for (;;) {
-      if (idx == 0)
-        break;
-      if (idx & kFlagBlock)
+      if (UNLIKELY((idx == 0) || (idx & kFlagBlock)))
         break;
       DCHECK(idx & kFlagSync);
       SyncVar * s = sync_alloc_.Map(idx & ~kFlagMask);
-      if (s->addr == addr) {
-        if (myidx != 0) {
+      if (LIKELY(s->addr == addr)) {
+        if (UNLIKELY(myidx != 0)) {
           mys->Reset(thr->proc());
           sync_alloc_.Free(&thr->proc()->sync_cache, myidx);
         }