--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -68,16 +68,22 @@
 #include "ProfilerParent.h"
 #include "mozilla/Services.h"
 #include "nsThreadUtils.h"
 #include "ProfilerMarkerPayload.h"
 #include "shared-libraries.h"
 #include "prdtoa.h"
 #include "prtime.h"
 
+#if defined(XP_WIN)
+#include <processthreadsapi.h>  // for GetCurrentProcessId()
+#else
+#include <unistd.h> // for getpid()
+#endif // defined(XP_WIN)
+
 #ifdef MOZ_TASK_TRACER
 #include "GeckoTaskTracer.h"
 #endif
 
 #if defined(GP_OS_android)
 # include "FennecJNINatives.h"
 # include "FennecJNIWrappers.h"
 #endif
@@ -423,16 +429,30 @@ private:
     for (uint32_t i = 0; i < mFilters.length(); ++i) {
       std::string filter = mFilters[i];
       std::transform(filter.begin(), filter.end(), filter.begin(), ::tolower);
 
       // Crude, non UTF-8 compatible, case insensitive substring search
       if (name.find(filter) != std::string::npos) {
         return true;
       }
+
+      // If the filter starts with pid:, check for a pid match
+      if (filter.find("pid:") == 0) {
+        std::string mypid = std::to_string(
+#ifdef XP_WIN
+          GetCurrentProcessId()
+#else
+          getpid()
+#endif
+        );
+        if (filter.compare(4, std::string::npos, mypid) == 0) {
+          return true;
+        }
+      }
     }
 
     return false;
   }
 
 public:
   static void Create(PSLockRef aLock, uint32_t aEntries, double aInterval,
                      uint32_t aFeatures,

--- a/tools/profiler/public/GeckoProfiler.h
+++ b/tools/profiler/public/GeckoProfiler.h
@@ -242,16 +242,22 @@ void profiler_shutdown();
 // Start the profiler -- initializing it first if necessary -- with the
 // selected options. Stops and restarts the profiler if it is already active.
 // After starting the profiler is "active". The samples will be recorded in a
 // circular buffer.
 //   "aEntries" is the number of entries in the profiler's circular buffer.
 //   "aInterval" the sampling interval, measured in millseconds.
 //   "aFeatures" is the feature set. Features unsupported by this
 //               platform/configuration are ignored.
+//   "aFilters" is the list of thread filters. Threads that do not match any
+//              of the filters are not profiled. A filter matches a thread if
+//              (a) the thread name contains the filter as a case-insensitive
+//                  substring, or
+//              (b) the filter is of the form "pid:<n>" where n is the process
+//                  id of the process that the thread is running in.
 void profiler_start(uint32_t aEntries, double aInterval, uint32_t aFeatures,
                     const char** aFilters, uint32_t aFilterCount);
 
 // Stop the profiler and discard the profile without saving it. A no-op if the
 // profiler is inactive. After stopping the profiler is "inactive".
 void profiler_stop();
 
 // If the profiler is inactive, start it. If it's already active, restart it if