Index: lib/fuzzer/FuzzerDefs.h
===================================================================
--- lib/fuzzer/FuzzerDefs.h
+++ lib/fuzzer/FuzzerDefs.h
@@ -176,12 +176,6 @@
 
 int FuzzerDriver(int *argc, char ***argv, UserCallback Callback);
 
-struct ScopedDoingMyOwnMemOrStr {
-  ScopedDoingMyOwnMemOrStr() { DoingMyOwnMemOrStr++; }
-  ~ScopedDoingMyOwnMemOrStr() { DoingMyOwnMemOrStr--; }
-  static int DoingMyOwnMemOrStr;
-};
-
 inline uint8_t  Bswap(uint8_t x)  { return x; }
 inline uint16_t Bswap(uint16_t x) { return __builtin_bswap16(x); }
 inline uint32_t Bswap(uint32_t x) { return __builtin_bswap32(x); }
@@ -191,6 +185,8 @@
 uint8_t *ExtraCountersEnd();
 void ClearExtraCounters();
 
+extern bool RunningUserCallback;
+
 }  // namespace fuzzer
 
 #endif  // LLVM_FUZZER_DEFS_H
Index: lib/fuzzer/FuzzerDictionary.h
===================================================================
--- lib/fuzzer/FuzzerDictionary.h
+++ lib/fuzzer/FuzzerDictionary.h
@@ -33,7 +33,6 @@
   }
 
   bool operator==(const FixedWord<kMaxSize> &w) const {
-    ScopedDoingMyOwnMemOrStr scoped_doing_my_own_mem_os_str;
     return Size == w.Size && 0 == memcmp(Data, w.Data, Size);
   }
 
Index: lib/fuzzer/FuzzerInternal.h
===================================================================
--- lib/fuzzer/FuzzerInternal.h
+++ lib/fuzzer/FuzzerInternal.h
@@ -117,7 +117,6 @@
   uint8_t *CurrentUnitData = nullptr;
   std::atomic<size_t> CurrentUnitSize;
   uint8_t BaseSha1[kSHA1NumBytes];  // Checksum of the base unit.
-  bool RunningCB = false;
 
   bool GracefulExitRequested = false;
 
Index: lib/fuzzer/FuzzerLoop.cpp
===================================================================
--- lib/fuzzer/FuzzerLoop.cpp
+++ lib/fuzzer/FuzzerLoop.cpp
@@ -43,6 +43,8 @@
 
 SharedMemoryRegion SMR;
 
+bool RunningUserCallback = false;
+
 // Only one Fuzzer per process.
 static Fuzzer *F;
 
@@ -242,7 +244,7 @@
 }
 
 void Fuzzer::ExitCallback() {
-  if (!RunningCB)
+  if (!RunningUserCallback)
     return; // This exit did not come from the user callback
   if (EF->__sanitizer_acquire_crash_state &&
       !EF->__sanitizer_acquire_crash_state())
@@ -276,7 +278,7 @@
   if (!InFuzzingThread())
     return;
 #endif
-  if (!RunningCB)
+  if (!RunningUserCallback)
     return; // We have not started running units yet.
   size_t Seconds =
       duration_cast<seconds>(system_clock::now() - UnitStartTime).count();
@@ -522,9 +524,9 @@
   AllocTracer.Start(Options.TraceMalloc);
   UnitStartTime = system_clock::now();
   TPC.ResetMaps();
-  RunningCB = true;
+  RunningUserCallback = true;
   int Res = CB(DataCopy, Size);
-  RunningCB = false;
+  RunningUserCallback = false;
   UnitStopTime = system_clock::now();
   (void)Res;
   assert(Res == 0);
Index: lib/fuzzer/FuzzerMutate.cpp
===================================================================
--- lib/fuzzer/FuzzerMutate.cpp
+++ lib/fuzzer/FuzzerMutate.cpp
@@ -195,7 +195,6 @@
     const void *Arg1Mutation, const void *Arg2Mutation,
     size_t ArgSize, const uint8_t *Data,
     size_t Size) {
-  ScopedDoingMyOwnMemOrStr scoped_doing_my_own_mem_os_str;
   bool HandleFirst = Rand.RandBool();
   const void *ExistingBytes, *DesiredBytes;
   Word W;
Index: lib/fuzzer/FuzzerTracePC.h
===================================================================
--- lib/fuzzer/FuzzerTracePC.h
+++ lib/fuzzer/FuzzerTracePC.h
@@ -169,7 +169,6 @@
 
   std::pair<size_t, size_t> FocusFunction = {-1, -1};  // Module and PC IDs.
 
-
   ValueBitMap ValueProfileMap;
   uintptr_t InitialStack;
 };
Index: lib/fuzzer/FuzzerTracePC.cpp
===================================================================
--- lib/fuzzer/FuzzerTracePC.cpp
+++ lib/fuzzer/FuzzerTracePC.cpp
@@ -39,8 +39,6 @@
 
 TracePC TPC;
 
-int ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr;
-
 uint8_t *TracePC::Counters() const {
   return __sancov_trace_pc_guard_8bit_counters;
 }
@@ -568,7 +566,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_memcmp(void *caller_pc, const void *s1,
                                   const void *s2, size_t n, int result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   if (result == 0) return;  // No reason to mutate.
   if (n <= 1) return;  // Not interesting.
   fuzzer::TPC.AddValueForMemcmp(caller_pc, s1, s2, n, /*StopAtZero*/false);
@@ -577,7 +575,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strncmp(void *caller_pc, const char *s1,
                                    const char *s2, size_t n, int result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   if (result == 0) return;  // No reason to mutate.
   size_t Len1 = fuzzer::InternalStrnlen(s1, n);
   size_t Len2 = fuzzer::InternalStrnlen(s2, n);
@@ -590,7 +588,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strcmp(void *caller_pc, const char *s1,
                                    const char *s2, int result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   if (result == 0) return;  // No reason to mutate.
   size_t N = fuzzer::InternalStrnlen2(s1, s2);
   if (N <= 1) return;  // Not interesting.
@@ -600,7 +598,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strncasecmp(void *called_pc, const char *s1,
                                        const char *s2, size_t n, int result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   return __sanitizer_weak_hook_strncmp(called_pc, s1, s2, n, result);
 }
 
@@ -607,7 +605,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strcasecmp(void *called_pc, const char *s1,
                                       const char *s2, int result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   return __sanitizer_weak_hook_strcmp(called_pc, s1, s2, result);
 }
 
@@ -614,7 +612,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strstr(void *called_pc, const char *s1,
                                   const char *s2, char *result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), strlen(s2));
 }
 
@@ -621,7 +619,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_strcasestr(void *called_pc, const char *s1,
                                       const char *s2, char *result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), strlen(s2));
 }
 
@@ -628,7 +626,7 @@
 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 void __sanitizer_weak_hook_memmem(void *called_pc, const void *s1, size_t len1,
                                   const void *s2, size_t len2, void *result) {
-  if (fuzzer::ScopedDoingMyOwnMemOrStr::DoingMyOwnMemOrStr) return;
+  if (!fuzzer::RunningUserCallback) return;
   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), len2);
 }
 }  // extern "C"