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
@@ -314,6 +314,41 @@
 
   ThreadRegistry thread_registry;
 
+  // This is used to prevent a very unlikely but very pathological behavior.
+  // Since memory access handling is not synchronized with DoReset,
+  // a thread running concurrently with DoReset can leave a bogus shadow value
+  // that will be later falsely detected as a race. For such false races
+  // RestoreStack will return false and we will not report it.
+  // However, consider that a thread leaves a whole lot of such bogus values
+  // and these values are later read by a whole lot of threads.
+  // This will cause massive amounts of ReportRace calls and lots of
+  // serialization. In very pathological cases the resulting slowdown
+  // can be >100x. This is very unlikely, but it was presumably observed
+  // in practice: https://github.com/google/sanitizers/issues/1552
+  // If this happens, previous access sid+epoch will be the same for all of
+  // these false races b/c if the thread will try to increment epoch, it will
+  // notice that DoReset has happened and will stop producing bogus shadow
+  // values. So, last_spurious_race is used to remember the last sid+epoch
+  // for which RestoreStack returned false. Then it is used to filter out
+  // races with the same sid+epoch very early and quickly.
+  // It is of course possible that multiple threads left multiple bogus shadow
+  // values and all of them are read by lots of threads at the same time.
+  // In such case last_spurious_race will only be able to deduplicate a few
+  // races from one thread, then few from another and so on. An alternative
+  // would be to hold an array of such sid+epoch, but we consider such scenario
+  // as even less likely.
+  // Note: this can lead to some rare false negatives as well:
+  // 1. When a legit access with the same sid+epoch participates in a race
+  // as the "previous" memory access, it will be wrongly filtered out.
+  // 2. When RestoreStack returns false for a legit memory access because it
+  // was already evicted from the thread trace, we will still remember it in
+  // last_spurious_race. Then if there is another racing memory access from
+  // the same thread that happened in the same epoch, but was stored in the
+  // next thread trace part (which is still preserved in the thread trace),
+  // we will also wrongly filter it out while RestoreStack would actually
+  // succeed for that second memory access.
+  RawShadow last_spurious_race;
+
   Mutex racy_mtx;
   Vector<RacyStacks> racy_stacks;
   // Number of fired suppressions may be large enough.
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
@@ -204,6 +204,7 @@
   }
   DPrintf("Resetting meta shadow...\n");
   ctx->metamap.ResetClocks();
+  StoreShadow(&ctx->last_spurious_race, Shadow::kEmpty);
   ctx->resetting = false;
 }
 
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_access.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_access.cpp
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_access.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_access.cpp
@@ -145,15 +145,6 @@
   TraceEvent(thr, ev);
 }
 
-ALWAYS_INLINE RawShadow LoadShadow(RawShadow* p) {
-  return static_cast<RawShadow>(
-      atomic_load((atomic_uint32_t*)p, memory_order_relaxed));
-}
-
-ALWAYS_INLINE void StoreShadow(RawShadow* sp, RawShadow s) {
-  atomic_store((atomic_uint32_t*)sp, static_cast<u32>(s), memory_order_relaxed);
-}
-
 NOINLINE void DoReportRace(ThreadState* thr, RawShadow* shadow_mem, Shadow cur,
                            Shadow old,
                            AccessType typ) SANITIZER_NO_THREAD_SAFETY_ANALYSIS {
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
@@ -701,6 +701,11 @@
   return false;
 }
 
+static bool SpuriousRace(Shadow old) {
+  Shadow last(LoadShadow(&ctx->last_spurious_race));
+  return last.sid() == old.sid() && last.epoch() == old.epoch();
+}
+
 void ReportRace(ThreadState *thr, RawShadow *shadow_mem, Shadow cur, Shadow old,
                 AccessType typ0) {
   CheckedMutex::CheckNoLocks();
@@ -721,6 +726,8 @@
       ((typ0 & kAccessAtomic) || (typ1 & kAccessAtomic)) &&
       !(typ0 & kAccessFree) && !(typ1 & kAccessFree))
     return;
+  if (SpuriousRace(old))
+    return;
 
   const uptr kMop = 2;
   Shadow s[kMop] = {cur, old};
@@ -760,9 +767,13 @@
   Lock slot_lock(&ctx->slots[static_cast<uptr>(s[1].sid())].mtx);
   ThreadRegistryLock l0(&ctx->thread_registry);
   Lock slots_lock(&ctx->slot_mtx);
+  if (SpuriousRace(old))
+    return;
   if (!RestoreStack(EventType::kAccessExt, s[1].sid(), s[1].epoch(), addr1,
-                    size1, typ1, &tids[1], &traces[1], mset[1], &tags[1]))
+                    size1, typ1, &tids[1], &traces[1], mset[1], &tags[1])) {
+    StoreShadow(&ctx->last_spurious_race, old.raw());
     return;
+  }
 
   if (IsFiredSuppression(ctx, rep_typ, traces[1]))
     return;
diff --git a/compiler-rt/lib/tsan/rtl/tsan_shadow.h b/compiler-rt/lib/tsan/rtl/tsan_shadow.h
--- a/compiler-rt/lib/tsan/rtl/tsan_shadow.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_shadow.h
@@ -178,6 +178,16 @@
 
 static_assert(sizeof(Shadow) == kShadowSize, "bad Shadow size");
 
+ALWAYS_INLINE RawShadow LoadShadow(RawShadow *p) {
+  return static_cast<RawShadow>(
+      atomic_load((atomic_uint32_t *)p, memory_order_relaxed));
+}
+
+ALWAYS_INLINE void StoreShadow(RawShadow *sp, RawShadow s) {
+  atomic_store((atomic_uint32_t *)sp, static_cast<u32>(s),
+               memory_order_relaxed);
+}
+
 }  // namespace __tsan
 
 #endif