--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -1632,19 +1632,25 @@ PrintUsageThenExit(int aExitCode)
     "  the profiler's circular buffer when the profiler is first started.\n"
     "  If unset, the platform default is used.\n"
     "\n"
     "  MOZ_PROFILER_STARTUP_INTERVAL=<1..1000>\n"
     "  If MOZ_PROFILER_STARTUP is set, specifies the sample interval,\n"
     "  measured in milliseconds, when the profiler is first started.\n"
     "  If unset, the platform default is used.\n"
     "\n"
+    "  MOZ_PROFILER_STARTUP_FEATURES_BITFIELD=<Number>\n"
+    "  If MOZ_PROFILER_STARTUP is set, specifies the profiling features, as\n"
+    "  the integer value of the features bitfield.\n"
+    "  If unset, the value from MOZ_PROFILER_STARTUP_FEATURES is used.\n"
+    "\n"
     "  MOZ_PROFILER_STARTUP_FEATURES=<Features>\n"
-    "  If MOZ_PROFILER_STARTUP is set, specifies the profiling features, as a\n"
-    "  comma-separated list of strings.\n"
+    "  If MOZ_PROFILER_STARTUP is set, specifies the profiling features, as\n"
+    "  a comma-separated list of strings.\n"
+    "  Ignored if  MOZ_PROFILER_STARTUP_FEATURES_BITFIELD is set.\n"
     "  If unset, the platform default is used.\n"
     "\n"
     "  MOZ_PROFILER_STARTUP_FILTERS=<Filters>\n"
     "  If MOZ_PROFILER_STARTUP is set, specifies the thread filters, as a\n"
     "  comma-separated list of strings. A given thread will be sampled if any\n"
     "  of the filters is a case-insensitive substring of the thread name.\n"
     "  If unset, a default is used.\n"
     "\n"
@@ -2213,24 +2219,38 @@ profiler_init(void* aStackTop)
       interval = PR_strtod(startupInterval, nullptr);
       if (errno == 0 && interval > 0.0 && interval <= 1000.0) {
         LOG("- MOZ_PROFILER_STARTUP_INTERVAL = %f", interval);
       } else {
         PrintUsageThenExit(1);
       }
     }
 
-    const char* startupFeatures = getenv("MOZ_PROFILER_STARTUP_FEATURES");
-    if (startupFeatures) {
-      UniquePtr<char[]> featureStringStorage;
-      nsTArray<const char*> featureStringArray =
-        SplitAtCommas(startupFeatures, featureStringStorage);
-      features = ParseFeaturesFromStringArray(featureStringArray.Elements(),
-                                              featureStringArray.Length());
-      LOG("- MOZ_PROFILER_STARTUP_FEATURES = %d", features);
+    const char* startupFeaturesBitfield =
+      getenv("MOZ_PROFILER_STARTUP_FEATURES_BITFIELD");
+    if (startupFeaturesBitfield) {
+      errno = 0;
+      features = strtol(startupFeaturesBitfield, nullptr, 10);
+      if (errno == 0 && features != 0) {
+        LOG("- MOZ_PROFILER_STARTUP_FEATURES_BITFIELD = %d", features);
+      } else {
+        PrintUsageThenExit(1);
+      }
+    } else {
+      const char* startupFeatures = getenv("MOZ_PROFILER_STARTUP_FEATURES");
+      if (startupFeatures) {
+        // Interpret startupFeatures as a list of feature strings, separated by
+        // commas.
+        UniquePtr<char[]> featureStringStorage;
+        nsTArray<const char*> featureStringArray =
+          SplitAtCommas(startupFeatures, featureStringStorage);
+        features = ParseFeaturesFromStringArray(featureStringArray.Elements(),
+                                                featureStringArray.Length());
+        LOG("- MOZ_PROFILER_STARTUP_FEATURES = %d", features);
+      }
     }
 
     const char* startupFilters = getenv("MOZ_PROFILER_STARTUP_FILTERS");
     if (startupFilters) {
       filters = SplitAtCommas(startupFilters, filterStorage);
       LOG("- MOZ_PROFILER_STARTUP_FILTERS = %s", startupFilters);
     }