diff --git a/libbacktrace/thread_utils.c b/libbacktrace/thread_utils.c
new file mode 100644
index 0000000..6f4cd3c
--- /dev/null
+++ b/libbacktrace/thread_utils.c
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "thread_utils.h"
+
+#if defined(__APPLE__)
+
+#include <sys/syscall.h>
+
+// Mac OS >= 10.6 has a system call equivalent to Linux's gettid().
+pid_t gettid() {
+  return syscall(SYS_thread_selfid);
+}
+
+#elif !defined(__BIONIC__)
+
+// glibc doesn't implement or export either gettid or tgkill.
+#include <unistd.h>
+#include <sys/syscall.h>
+
+pid_t gettid() {
+  return syscall(__NR_gettid);
+}
+
+int tgkill(int tgid, int tid, int sig) {
+  return syscall(__NR_tgkill, tgid, tid, sig);
+}
+
+#endif