diff --git a/include/v8.h b/include/v8.h
index a716793ccc..12da59f2a0 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -8636,7 +8636,11 @@ class V8_EXPORT V8 {
   /**
    * Sets V8 flags from a string.
    */
-  static void SetFlagsFromString(const char* str, int length);
+  static void SetFlagsFromString(const char* str);
+  static void SetFlagsFromString(const char* str, size_t length);
+  V8_DEPRECATE_SOON("use size_t version",
+                    static void SetFlagsFromString(const char* str,
+                                                   int length));
 
   /**
    * Sets V8 flags from the command line.
diff --git a/src/api.cc b/src/api.cc
index 5cc20b077c..eec965b43c 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -891,11 +891,19 @@ void V8::SetDcheckErrorHandler(DcheckErrorCallback that) {
   v8::base::SetDcheckFunction(that);
 }
 
-void V8::SetFlagsFromString(const char* str, int length) {
+void V8::SetFlagsFromString(const char* str) {
+  SetFlagsFromString(str, strlen(str));
+}
+
+void V8::SetFlagsFromString(const char* str, size_t length) {
   i::FlagList::SetFlagsFromString(str, length);
   i::FlagList::EnforceFlagImplications();
 }
 
+void V8::SetFlagsFromString(const char* str, int length) {
+  CHECK_LE(0, length);
+  SetFlagsFromString(str, static_cast<size_t>(length));
+}
 
 void V8::SetFlagsFromCommandLine(int* argc, char** argv, bool remove_flags) {
   i::FlagList::SetFlagsFromCommandLine(argc, argv, remove_flags);
@@ -10494,12 +10502,6 @@ int Testing::GetStressRuns() {
 #endif
 }
 
-
-static void SetFlagsFromString(const char* flags) {
-  V8::SetFlagsFromString(flags, i::StrLength(flags));
-}
-
-
 void Testing::PrepareStressRun(int run) {
   static const char* kLazyOptimizations =
       "--prepare-always-opt "
@@ -10513,22 +10515,22 @@ void Testing::PrepareStressRun(int run) {
   static const char* kDeoptEvery13Times = "--deopt-every-n-times=13";
   if (internal::Testing::stress_type() == Testing::kStressTypeDeopt &&
       internal::FLAG_deopt_every_n_times == 0) {
-    SetFlagsFromString(kDeoptEvery13Times);
+    V8::SetFlagsFromString(kDeoptEvery13Times);
   }
 
 #ifdef DEBUG
   // As stressing in debug mode only make two runs skip the deopt stressing
   // here.
   if (run == GetStressRuns() - 1) {
-    SetFlagsFromString(kForcedOptimizations);
+    V8::SetFlagsFromString(kForcedOptimizations);
   } else {
-    SetFlagsFromString(kLazyOptimizations);
+    V8::SetFlagsFromString(kLazyOptimizations);
   }
 #else
   if (run == GetStressRuns() - 1) {
-    SetFlagsFromString(kForcedOptimizations);
+    V8::SetFlagsFromString(kForcedOptimizations);
   } else if (run != GetStressRuns() - 2) {
-    SetFlagsFromString(kLazyOptimizations);
+    V8::SetFlagsFromString(kLazyOptimizations);
   }
 #endif
 }
diff --git a/src/d8.cc b/src/d8.cc
index be90dd0859..acbe4b78f9 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -2794,12 +2794,6 @@ void Worker::PostMessageOut(const v8::FunctionCallbackInfo<v8::Value>& args) {
   }
 }
 
-
-void SetFlagsFromString(const char* flags) {
-  v8::V8::SetFlagsFromString(flags, static_cast<int>(strlen(flags)));
-}
-
-
 bool Shell::SetOptions(int argc, char* argv[]) {
   bool logfile_per_isolate = false;
   for (int i = 0; i < argc; i++) {
@@ -2976,7 +2970,7 @@ bool Shell::SetOptions(int argc, char* argv[]) {
   current->End(argc);
 
   if (!logfile_per_isolate && options.num_isolates) {
-    SetFlagsFromString("--nologfile_per_isolate");
+    V8::SetFlagsFromString("--no-logfile-per-isolate");
   }
 
   return true;
@@ -3414,10 +3408,10 @@ int Shell::Main(int argc, char* argv[]) {
   }
 
   if (i::FLAG_trace_turbo_cfg_file == nullptr) {
-    SetFlagsFromString("--trace-turbo-cfg-file=turbo.cfg");
+    V8::SetFlagsFromString("--trace-turbo-cfg-file=turbo.cfg");
   }
   if (i::FLAG_redirect_code_traces_to == nullptr) {
-    SetFlagsFromString("--redirect-code-traces-to=code.asm");
+    V8::SetFlagsFromString("--redirect-code-traces-to=code.asm");
   }
   v8::V8::InitializePlatform(g_platform.get());
   v8::V8::Initialize();
diff --git a/src/flags.cc b/src/flags.cc
index d16c547c52..c87e5d5d45 100644
--- a/src/flags.cc
+++ b/src/flags.cc
@@ -526,14 +526,14 @@ static char* SkipBlackSpace(char* p) {
 
 
 // static
-int FlagList::SetFlagsFromString(const char* str, int len) {
+int FlagList::SetFlagsFromString(const char* str, size_t len) {
   // make a 0-terminated copy of str
-  ScopedVector<char> copy0(len + 1);
-  MemCopy(copy0.start(), str, len);
+  std::unique_ptr<char[]> copy0{NewArray<char>(len + 1)};
+  MemCopy(copy0.get(), str, len);
   copy0[len] = '\0';
 
   // strip leading white space
-  char* copy = SkipWhiteSpace(copy0.start());
+  char* copy = SkipWhiteSpace(copy0.get());
 
   // count the number of 'arguments'
   int argc = 1;  // be compatible with SetFlagsFromCommandLine()
@@ -557,7 +557,6 @@ int FlagList::SetFlagsFromString(const char* str, int len) {
   return SetFlagsFromCommandLine(&argc, argv.start(), false);
 }
 
-
 // static
 void FlagList::ResetAllFlags() {
   for (size_t i = 0; i < num_flags; ++i) {
diff --git a/src/flags.h b/src/flags.h
index d82c5b40d1..7e6e0cb715 100644
--- a/src/flags.h
+++ b/src/flags.h
@@ -51,7 +51,7 @@ class V8_EXPORT_PRIVATE FlagList {
   // Set the flag values by parsing the string str. Splits string into argc
   // substrings argv[], each of which consisting of non-white-space chars,
   // and then calls SetFlagsFromCommandLine() and returns its result.
-  static int SetFlagsFromString(const char* str, int len);
+  static int SetFlagsFromString(const char* str, size_t len);
 
   // Reset all flags to their default value.
   static void ResetAllFlags();
diff --git a/src/third_party/vtune/vtune-jit.cc b/src/third_party/vtune/vtune-jit.cc
index 5c49855359..dbbab7fc58 100644
--- a/src/third_party/vtune/vtune-jit.cc
+++ b/src/third_party/vtune/vtune-jit.cc
@@ -257,8 +257,7 @@ void VTUNEJITInterface::event_handler(const v8::JitCodeEvent* event) {
 }  // namespace internal
 
 v8::JitCodeEventHandler GetVtuneCodeEventHandler() {
-  v8::V8::SetFlagsFromString("--nocompact_code_space",
-                             (int)strlen("--nocompact_code_space"));
+  v8::V8::SetFlagsFromString("--no-compact-code-space");
   return vTune::internal::VTUNEJITInterface::event_handler;
 }
 
diff --git a/test/cctest/heap/test-heap.cc b/test/cctest/heap/test-heap.cc
index 166e1e7019..1d1066bc82 100644
--- a/test/cctest/heap/test-heap.cc
+++ b/test/cctest/heap/test-heap.cc
@@ -5144,7 +5144,7 @@ TEST(MessageObjectLeak) {
   CompileRun(test);
 
   const char* flag = "--turbo-filter=*";
-  FlagList::SetFlagsFromString(flag, StrLength(flag));
+  FlagList::SetFlagsFromString(flag, strlen(flag));
   FLAG_always_opt = true;
 
   CompileRun(test);
diff --git a/test/cctest/test-flags.cc b/test/cctest/test-flags.cc
index e38a61f4b3..596a84082f 100644
--- a/test/cctest/test-flags.cc
+++ b/test/cctest/test-flags.cc
@@ -80,7 +80,7 @@ TEST(Flags2b) {
       "-notesting-maybe-bool-flag   "
       "-testing_float_flag=.25  "
       "--testing_string_flag   no_way!  ";
-  CHECK_EQ(0, FlagList::SetFlagsFromString(str, StrLength(str)));
+  CHECK_EQ(0, FlagList::SetFlagsFromString(str, strlen(str)));
   CHECK(!FLAG_testing_bool_flag);
   CHECK(FLAG_testing_maybe_bool_flag.has_value);
   CHECK(!FLAG_testing_maybe_bool_flag.value);
@@ -117,7 +117,7 @@ TEST(Flags3b) {
       "--testing_int_flag -666 "
       "--testing_float_flag -12E10 "
       "-testing-string-flag=foo-bar";
-  CHECK_EQ(0, FlagList::SetFlagsFromString(str, StrLength(str)));
+  CHECK_EQ(0, FlagList::SetFlagsFromString(str, strlen(str)));
   CHECK(FLAG_testing_bool_flag);
   CHECK(FLAG_testing_maybe_bool_flag.has_value);
   CHECK(FLAG_testing_maybe_bool_flag.value);
@@ -142,7 +142,7 @@ TEST(Flags4) {
 TEST(Flags4b) {
   SetFlagsToDefault();
   const char* str = "--testing_bool_flag --foo";
-  CHECK_EQ(2, FlagList::SetFlagsFromString(str, StrLength(str)));
+  CHECK_EQ(2, FlagList::SetFlagsFromString(str, strlen(str)));
   CHECK(!FLAG_testing_maybe_bool_flag.has_value);
 }
 
@@ -161,7 +161,7 @@ TEST(Flags5) {
 TEST(Flags5b) {
   SetFlagsToDefault();
   const char* str = "                     --testing_int_flag=\"foobar\"";
-  CHECK_EQ(1, FlagList::SetFlagsFromString(str, StrLength(str)));
+  CHECK_EQ(1, FlagList::SetFlagsFromString(str, strlen(str)));
 }
 
 
@@ -180,7 +180,7 @@ TEST(Flags6) {
 TEST(Flags6b) {
   SetFlagsToDefault();
   const char* str = "       --testing-int-flag 0      --testing_float_flag    ";
-  CHECK_EQ(3, FlagList::SetFlagsFromString(str, StrLength(str)));
+  CHECK_EQ(3, FlagList::SetFlagsFromString(str, strlen(str)));
 }
 
 TEST(FlagsRemoveIncomplete) {
diff --git a/test/cctest/test-serialize.cc b/test/cctest/test-serialize.cc
index 2703113838..38e0eb19fc 100644
--- a/test/cctest/test-serialize.cc
+++ b/test/cctest/test-serialize.cc
@@ -1843,7 +1843,7 @@ TEST(CodeSerializerLargeCodeObjectWithIncrementalMarking) {
   ManualGCScope manual_gc_scope;
   FLAG_always_opt = false;
   const char* filter_flag = "--turbo-filter=NOTHING";
-  FlagList::SetFlagsFromString(filter_flag, StrLength(filter_flag));
+  FlagList::SetFlagsFromString(filter_flag, strlen(filter_flag));
   FLAG_manual_evacuation_candidates_selection = true;
 
   LocalContext context;