diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt
index 9d43909d068..75ce6f45603 100644
--- a/Documentation/technical/api-trace2.txt
+++ b/Documentation/technical/api-trace2.txt
@@ -769,6 +769,42 @@ The "value" field may be an integer or a string.
 }
 ------------
 
+`"th_timer"`::
+	This event logs the amount of time that a stopwatch timer was
+	running in the thread.  This event is generated when a thread
+	exits for timers that requested per-thread events.
++
+------------
+{
+	"event":"th_timer",
+	...
+	"category":"my_category",
+	"name":"my_timer",
+	"intervals":5,         # number of time it was started/stopped
+	"t_total":0.052741,    # total time in seconds it was running
+	"t_min":0.010061,      # shortest interval
+	"t_max":0.011648       # longest interval
+}
+------------
+
+`"timer"`::
+	This event logs the amount of time that a stopwatch timer was
+	running aggregated across all threads.  This event is generated
+	when the process exits.
++
+------------
+{
+	"event":"timer",
+	...
+	"category":"my_category",
+	"name":"my_timer",
+	"intervals":5,         # number of time it was started/stopped
+	"t_total":0.052741,    # total time in seconds it was running
+	"t_min":0.010061,      # shortest interval
+	"t_max":0.011648       # longest interval
+}
+------------
+
 == Example Trace2 API Usage
 
 Here is a hypothetical usage of the Trace2 API showing the intended
@@ -1200,6 +1236,60 @@ d0 | main                     | data         | r0  |  0.002126 |  0.002126 | fsy
 d0 | main                     | exit         |     |  0.000470 |           |              | code:0
 d0 | main                     | atexit       |     |  0.000477 |           |              | code:0
 ----------------
+
+Stopwatch Timer Events::
+
+	Measure the time spent in a function call or span of code
+	that might be called from many places within the code
+	throughout the life of the process.
++
+----------------
+static void expensive_function(void)
+{
+	trace2_timer_start(TRACE2_TIMER_ID_TEST1);
+	...
+	sleep_millisec(1000); // Do something expensive
+	...
+	trace2_timer_stop(TRACE2_TIMER_ID_TEST1);
+}
+
+static int ut_100timer(int argc, const char **argv)
+{
+	...
+
+	expensive_function();
+
+	// Do something else 1...
+
+	expensive_function();
+
+	// Do something else 2...
+
+	expensive_function();
+
+	return 0;
+}
+----------------
++
+In this example, we measure the total time spent in
+`expensive_function()` regardless of when it is called
+in the overall flow of the program.
++
+----------------
+$ export GIT_TRACE2_PERF_BRIEF=1
+$ export GIT_TRACE2_PERF=~/log.perf
+$ t/helper/test-tool trace2 100timer 3 1000
+...
+$ cat ~/log.perf
+d0 | main                     | version      |     |           |           |              | ...
+d0 | main                     | start        |     |  0.001453 |           |              | t/helper/test-tool trace2 100timer 3 1000
+d0 | main                     | cmd_name     |     |           |           |              | trace2 (trace2)
+d0 | main                     | exit         |     |  3.003667 |           |              | code:0
+d0 | main                     | timer        |     |           |           | test         | name:test1 intervals:3 total:3.001686 min:1.000254 max:1.000929
+d0 | main                     | atexit       |     |  3.003796 |           |              | code:0
+----------------
+
+
 == Future Work
 
 === Relationship to the Existing Trace Api (api-trace.txt)
diff --git a/Makefile b/Makefile
index cac3452edb9..820649bf62a 100644
--- a/Makefile
+++ b/Makefile
@@ -1102,6 +1102,7 @@ LIB_OBJS += trace2/tr2_tgt_event.o
 LIB_OBJS += trace2/tr2_tgt_normal.o
 LIB_OBJS += trace2/tr2_tgt_perf.o
 LIB_OBJS += trace2/tr2_tls.o
+LIB_OBJS += trace2/tr2_tmr.o
 LIB_OBJS += trailer.o
 LIB_OBJS += transport-helper.o
 LIB_OBJS += transport.o
diff --git a/t/helper/test-trace2.c b/t/helper/test-trace2.c
index a714130ece7..f951b9e97d7 100644
--- a/t/helper/test-trace2.c
+++ b/t/helper/test-trace2.c
@@ -228,6 +228,101 @@ static int ut_010bug_BUG(int argc, const char **argv)
 	BUG("a %s message", "BUG");
 }
 
+/*
+ * Single-threaded timer test.  Create several intervals using the
+ * TEST1 timer.  The test script can verify that an aggregate Trace2
+ * "timer" event is emitted indicating that we started+stopped the
+ * timer the requested number of times.
+ */
+static int ut_100timer(int argc, const char **argv)
+{
+	const char *usage_error =
+		"expect <count> <ms_delay>";
+
+	int count = 0;
+	int delay = 0;
+	int k;
+
+	if (argc != 2)
+		die("%s", usage_error);
+	if (get_i(&count, argv[0]))
+		die("%s", usage_error);
+	if (get_i(&delay, argv[1]))
+		die("%s", usage_error);
+
+	for (k = 0; k < count; k++) {
+		trace2_timer_start(TRACE2_TIMER_ID_TEST1);
+		sleep_millisec(delay);
+		trace2_timer_stop(TRACE2_TIMER_ID_TEST1);
+	}
+
+	return 0;
+}
+
+struct ut_101_data {
+	int count;
+	int delay;
+};
+
+static void *ut_101timer_thread_proc(void *_ut_101_data)
+{
+	struct ut_101_data *data = _ut_101_data;
+	int k;
+
+	trace2_thread_start("ut_101");
+
+	for (k = 0; k < data->count; k++) {
+		trace2_timer_start(TRACE2_TIMER_ID_TEST2);
+		sleep_millisec(data->delay);
+		trace2_timer_stop(TRACE2_TIMER_ID_TEST2);
+	}
+
+	trace2_thread_exit();
+	return NULL;
+}
+
+/*
+ * Multi-threaded timer test.  Create several threads that each create
+ * several intervals using the TEST2 timer.  The test script can verify
+ * that an individual Trace2 "th_timer" events for each thread and an
+ * aggregate "timer" event are generated.
+ */
+static int ut_101timer(int argc, const char **argv)
+{
+	const char *usage_error =
+		"expect <count> <ms_delay> <threads>";
+
+	struct ut_101_data data = { 0, 0 };
+	int nr_threads = 0;
+	int k;
+	pthread_t *pids = NULL;
+
+	if (argc != 3)
+		die("%s", usage_error);
+	if (get_i(&data.count, argv[0]))
+		die("%s", usage_error);
+	if (get_i(&data.delay, argv[1]))
+		die("%s", usage_error);
+	if (get_i(&nr_threads, argv[2]))
+		die("%s", usage_error);
+
+	CALLOC_ARRAY(pids, nr_threads);
+
+	for (k = 0; k < nr_threads; k++) {
+		if (pthread_create(&pids[k], NULL, ut_101timer_thread_proc, &data))
+			die("failed to create thread[%d]", k);
+	}
+
+	for (k = 0; k < nr_threads; k++) {
+		if (pthread_join(pids[k], NULL))
+			die("failed to join thread[%d]", k);
+	}
+
+	free(pids);
+
+	return 0;
+}
+
 /*
  * Usage:
  *     test-tool trace2 <ut_name_1> <ut_usage_1>
@@ -248,6 +343,9 @@ static struct unit_test ut_table[] = {
 	{ ut_008bug,      "008bug",    "" },
 	{ ut_009bug_BUG,  "009bug_BUG","" },
 	{ ut_010bug_BUG,  "010bug_BUG","" },
+
+	{ ut_100timer,    "100timer",  "<count> <ms_delay>" },
+	{ ut_101timer,    "101timer",  "<count> <ms_delay> <threads>" },
 };
 /* clang-format on */
 
diff --git a/t/t0211-trace2-perf.sh b/t/t0211-trace2-perf.sh
index 22d0845544e..5c28424e657 100755
--- a/t/t0211-trace2-perf.sh
+++ b/t/t0211-trace2-perf.sh
@@ -173,4 +173,53 @@ test_expect_success 'using global config, perf stream, return code 0' '
 	test_cmp expect actual
 '
 
+# Exercise the stopwatch timers in a loop and confirm that we have
+# as many start/stop intervals as expected.  We cannot really test the
+# actual (total, min, max) timer values, so we have to assume that they
+# are good, but we can verify the interval count.
+#
+# The timer "test/test1" should only emit a global summary "timer" event.
+# The timer "test/test2" should emit per-thread "th_timer" events and a
+# global summary "timer" event.
+
+have_timer_event () {
+	thread=$1 event=$2 category=$3 name=$4 intervals=$5 file=$6 &&
+
+	pattern="d0|${thread}|${event}||||${category}|name:${name} intervals:${intervals}" &&
+
+	grep "${pattern}" ${file}
+}
+
+test_expect_success 'stopwatch timer test/test1' '
+	test_when_finished "rm trace.perf actual" &&
+	test_config_global trace2.perfBrief 1 &&
+	test_config_global trace2.perfTarget "$(pwd)/trace.perf" &&
+
+	# Use the timer "test1" 5 times from "main".
+	test-tool trace2 100timer 5 10 &&
+
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+
+	have_timer_event "main" "timer" "test" "test1" 5 actual
+'
+
+test_expect_success 'stopwatch timer test/test2' '
+	test_when_finished "rm trace.perf actual" &&
+	test_config_global trace2.perfBrief 1 &&
+	test_config_global trace2.perfTarget "$(pwd)/trace.perf" &&
+
+	# Use the timer "test2" 5 times each in 3 threads.
+	test-tool trace2 101timer 5 10 3 &&
+
+	perl "$TEST_DIRECTORY/t0211/scrub_perf.perl" <trace.perf >actual &&
+
+	# So we should have 3 per-thread events of 5 each.
+	have_timer_event "th01:ut_101" "th_timer" "test" "test2" 5 actual &&
+	have_timer_event "th02:ut_101" "th_timer" "test" "test2" 5 actual &&
+	have_timer_event "th03:ut_101" "th_timer" "test" "test2" 5 actual &&
+
+	# And we should have 15 total uses.
+	have_timer_event "main" "timer" "test" "test2" 15 actual
+'
+
 test_done
diff --git a/t/t0211/scrub_perf.perl b/t/t0211/scrub_perf.perl
index 299999f0f89..7a50bae6463 100644
--- a/t/t0211/scrub_perf.perl
+++ b/t/t0211/scrub_perf.perl
@@ -64,6 +64,12 @@ while (<>) {
 	    goto SKIP_LINE;
 	}
     }
+    elsif ($tokens[$col_event] =~ m/timer/) {
+	# This also captures "th_timer" events
+	$tokens[$col_rest] =~ s/ total:\d+\.\d*/ total:_T_TOTAL_/;
+	$tokens[$col_rest] =~ s/ min:\d+\.\d*/ min:_T_MIN_/;
+	$tokens[$col_rest] =~ s/ max:\d+\.\d*/ max:_T_MAX_/;
+    }
 
     # t_abs and t_rel are either blank or a float.  Replace the float
     # with a constant for matching the HEREDOC in the test script.
diff --git a/trace2.c b/trace2.c
index 165264dc79a..a93cab7c2b7 100644
--- a/trace2.c
+++ b/trace2.c
@@ -13,6 +13,7 @@
 #include "trace2/tr2_sysenv.h"
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
+#include "trace2/tr2_tmr.h"
 
 static int trace2_enabled;
 
@@ -83,6 +84,23 @@ static void tr2_tgt_disable_builtins(void)
 		tgt_j->pfn_term();
 }
 
+/*
+ * The signature of this function must match the pfn_timer
+ * method in the targets.  (Think of this is an apply operation
+ * across the set of active targets.)
+ */
+static void tr2_tgt_emit_a_timer(const struct tr2_timer_metadata *meta,
+				 const struct tr2_timer *timer,
+				 int is_final_data)
+{
+	struct tr2_tgt *tgt_j;
+	int j;
+
+	for_each_wanted_builtin (j, tgt_j)
+		if (tgt_j->pfn_timer)
+			tgt_j->pfn_timer(meta, timer, is_final_data);
+}
+
 static int tr2main_exit_code;
 
 /*
@@ -110,6 +128,26 @@ static void tr2main_atexit_handler(void)
 	 */
 	tr2tls_pop_unwind_self();
 
+	/*
+	 * Some timers want per-thread details.  If the main thread
+	 * used one of those timers, emit the details now (before
+	 * we emit the aggregate timer values).
+	 */
+	tr2_emit_per_thread_timers(tr2_tgt_emit_a_timer);
+
+	/*
+	 * Add stopwatch timer data for the main thread to the final
+	 * totals.  And then emit the final timer values.
+	 *
+	 * Technically, we shouldn't need to hold the lock to update
+	 * and output the final_timer_block (since all other threads
+	 * should be dead by now), but it doesn't hurt anything.
+	 */
+	tr2tls_lock();
+	tr2_update_final_timers();
+	tr2_emit_final_timers(tr2_tgt_emit_a_timer);
+	tr2tls_unlock();
+
 	for_each_wanted_builtin (j, tgt_j)
 		if (tgt_j->pfn_atexit)
 			tgt_j->pfn_atexit(us_elapsed_absolute,
@@ -541,6 +579,21 @@ void trace2_thread_exit_fl(const char *file, int line)
 	tr2tls_pop_unwind_self();
 	us_elapsed_thread = tr2tls_region_elasped_self(us_now);
 
+	/*
+	 * Some timers want per-thread details.  If this thread used
+	 * one of those timers, emit the details now.
+	 */
+	tr2_emit_per_thread_timers(tr2_tgt_emit_a_timer);
+
+	/*
+	 * Add stopwatch timer data from the current (non-main) thread
+	 * to the final totals.  (We'll accumulate data for the main
+	 * thread later during "atexit".)
+	 */
+	tr2tls_lock();
+	tr2_update_final_timers();
+	tr2tls_unlock();
+
 	for_each_wanted_builtin (j, tgt_j)
 		if (tgt_j->pfn_thread_exit_fl)
 			tgt_j->pfn_thread_exit_fl(file, line,
@@ -795,6 +848,28 @@ void trace2_printf_fl(const char *file, int line, const char *fmt, ...)
 	va_end(ap);
 }
 
+void trace2_timer_start(enum trace2_timer_id tid)
+{
+	if (!trace2_enabled)
+		return;
+
+	if (tid < 0 || tid >= TRACE2_NUMBER_OF_TIMERS)
+		BUG("trace2_timer_start: invalid timer id: %d", tid);
+
+	tr2_start_timer(tid);
+}
+
+void trace2_timer_stop(enum trace2_timer_id tid)
+{
+	if (!trace2_enabled)
+		return;
+
+	if (tid < 0 || tid >= TRACE2_NUMBER_OF_TIMERS)
+		BUG("trace2_timer_stop: invalid timer id: %d", tid);
+
+	tr2_stop_timer(tid);
+}
+
 const char *trace2_session_id(void)
 {
 	return tr2_sid_get();
diff --git a/trace2.h b/trace2.h
index 74cdb1354f7..7a843ac0518 100644
--- a/trace2.h
+++ b/trace2.h
@@ -51,6 +51,7 @@ struct json_writer;
  * [] trace2_region*    -- emit region nesting messages.
  * [] trace2_data*      -- emit region/thread/repo data messages.
  * [] trace2_printf*    -- legacy trace[1] messages.
+ * [] trace2_timer*     -- stopwatch timers (messages are deferred).
  */
 
 /*
@@ -485,6 +486,48 @@ void trace2_printf_fl(const char *file, int line, const char *fmt, ...);
 
 #define trace2_printf(...) trace2_printf_fl(__FILE__, __LINE__, __VA_ARGS__)
 
+/*
+ * Define the set of stopwatch timers.
+ *
+ * We can add more at any time, but they must be defined at compile
+ * time (to avoid the need to dynamically allocate and synchronize
+ * them between different threads).
+ *
+ * These must start at 0 and be contiguous (because we use them
+ * elsewhere as array indexes).
+ *
+ * Any values added to this enum must also be added to the
+ * `tr2_timer_metadata[]` in `trace2/tr2_tmr.c`.
+ */
+enum trace2_timer_id {
+	/*
+	 * Define two timers for testing.  See `t/helper/test-trace2.c`.
+	 * These can be used for ad hoc testing, but should not be used
+	 * for permanent analysis code.
+	 */
+	TRACE2_TIMER_ID_TEST1 = 0, /* emits summary event only */
+	TRACE2_TIMER_ID_TEST2,     /* emits summary and thread events */
+
+	/* Add additional timer definitions before here. */
+	TRACE2_NUMBER_OF_TIMERS
+};
+
+/*
+ * Start/Stop the indicated stopwatch timer in the current thread.
+ *
+ * The time spent by the current thread between the _start and _stop
+ * calls will be added to the thread's partial sum for this timer.
+ *
+ * Timer events are emitted at thread and program exit.
+ *
+ * Note: Since the stopwatch API routines do not generate individual
+ * events, they do not take (file, line) arguments.  Similarly, the
+ * category and timer name values are defined at compile-time in the
+ * timer definitions array, so they are not needed here in the API.
+ */
+void trace2_timer_start(enum trace2_timer_id tid);
+void trace2_timer_stop(enum trace2_timer_id tid);
+
 /*
  * Optional platform-specific code to dump information about the
  * current and any parent process(es).  This is intended to allow
diff --git a/trace2/tr2_tgt.h b/trace2/tr2_tgt.h
index 65f94e15748..2a80bef0df5 100644
--- a/trace2/tr2_tgt.h
+++ b/trace2/tr2_tgt.h
@@ -4,6 +4,8 @@
 struct child_process;
 struct repository;
 struct json_writer;
+struct tr2_timer_metadata;
+struct tr2_timer;
 
 /*
  * Function prototypes for a TRACE2 "target" vtable.
@@ -96,6 +98,10 @@ typedef void(tr2_tgt_evt_printf_va_fl_t)(const char *file, int line,
 					 uint64_t us_elapsed_absolute,
 					 const char *fmt, va_list ap);
 
+typedef void(tr2_tgt_evt_timer_t)(const struct tr2_timer_metadata *meta,
+				  const struct tr2_timer *timer,
+				  int is_final_data);
+
 /*
  * "vtable" for a TRACE2 target.  Use NULL if a target does not want
  * to emit that message.
@@ -132,6 +138,7 @@ struct tr2_tgt {
 	tr2_tgt_evt_data_fl_t                   *pfn_data_fl;
 	tr2_tgt_evt_data_json_fl_t              *pfn_data_json_fl;
 	tr2_tgt_evt_printf_va_fl_t              *pfn_printf_va_fl;
+	tr2_tgt_evt_timer_t                     *pfn_timer;
 };
 /* clang-format on */
 
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 52f9356c695..1196da89ba4 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -9,6 +9,7 @@
 #include "trace2/tr2_sysenv.h"
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
+#include "trace2/tr2_tmr.h"
 
 static struct tr2_dst tr2dst_event = {
 	.sysenv_var = TR2_SYSENV_EVENT,
@@ -617,6 +618,30 @@ static void fn_data_json_fl(const char *file, int line,
 	}
 }
 
+static void fn_timer(const struct tr2_timer_metadata *meta,
+		     const struct tr2_timer *timer,
+		     int is_final_data)
+{
+	const char *event_name = is_final_data ? "timer" : "th_timer";
+	struct json_writer jw = JSON_WRITER_INIT;
+	double t_total = ((double)timer->total_ns) / 1000000000.0;
+	double t_min = ((double)timer->min_ns) / 1000000000.0;
+	double t_max = ((double)timer->max_ns) / 1000000000.0;
+
+	jw_object_begin(&jw, 0);
+	event_fmt_prepare(event_name, __FILE__, __LINE__, NULL, &jw);
+	jw_object_string(&jw, "category", meta->category);
+	jw_object_string(&jw, "name", meta->name);
+	jw_object_intmax(&jw, "intervals", timer->interval_count);
+	jw_object_double(&jw, "t_total", 6, t_total);
+	jw_object_double(&jw, "t_min", 6, t_min);
+	jw_object_double(&jw, "t_max", 6, t_max);
+	jw_end(&jw);
+
+	tr2_dst_write_line(&tr2dst_event, &jw.json);
+	jw_release(&jw);
+}
+
 struct tr2_tgt tr2_tgt_event = {
 	.pdst = &tr2dst_event,
 
@@ -648,4 +673,5 @@ struct tr2_tgt tr2_tgt_event = {
 	.pfn_data_fl = fn_data_fl,
 	.pfn_data_json_fl = fn_data_json_fl,
 	.pfn_printf_va_fl = NULL,
+	.pfn_timer = fn_timer,
 };
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index 69f80330778..3888c10ef50 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -8,6 +8,7 @@
 #include "trace2/tr2_tbuf.h"
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
+#include "trace2/tr2_tmr.h"
 
 static struct tr2_dst tr2dst_normal = {
 	.sysenv_var = TR2_SYSENV_NORMAL,
@@ -329,6 +330,27 @@ static void fn_printf_va_fl(const char *file, int line,
 	strbuf_release(&buf_payload);
 }
 
+static void fn_timer(const struct tr2_timer_metadata *meta,
+		     const struct tr2_timer *timer,
+		     int is_final_data)
+{
+	const char *event_name = is_final_data ? "timer" : "th_timer";
+	struct strbuf buf_payload = STRBUF_INIT;
+	double t_total = ((double)timer->total_ns) / 1000000000.0;
+	double t_min = ((double)timer->min_ns) / 1000000000.0;
+	double t_max = ((double)timer->max_ns) / 1000000000.0;
+
+	strbuf_addf(&buf_payload, ("%s %s/%s"
+				   " intervals:%"PRIu64
+				   " total:%8.6f min:%8.6f max:%8.6f"),
+		    event_name, meta->category, meta->name,
+		    timer->interval_count,
+		    t_total, t_min, t_max);
+
+	normal_io_write_fl(__FILE__, __LINE__, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
 struct tr2_tgt tr2_tgt_normal = {
 	.pdst = &tr2dst_normal,
 
@@ -360,4 +382,5 @@ struct tr2_tgt tr2_tgt_normal = {
 	.pfn_data_fl = NULL,
 	.pfn_data_json_fl = NULL,
 	.pfn_printf_va_fl = fn_printf_va_fl,
+	.pfn_timer = fn_timer,
 };
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index 59ca58f862d..89b30ddc0e4 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -10,6 +10,7 @@
 #include "trace2/tr2_tbuf.h"
 #include "trace2/tr2_tgt.h"
 #include "trace2/tr2_tls.h"
+#include "trace2/tr2_tmr.h"
 
 static struct tr2_dst tr2dst_perf = {
 	.sysenv_var = TR2_SYSENV_PERF,
@@ -555,6 +556,28 @@ static void fn_printf_va_fl(const char *file, int line,
 	strbuf_release(&buf_payload);
 }
 
+static void fn_timer(const struct tr2_timer_metadata *meta,
+		     const struct tr2_timer *timer,
+		     int is_final_data)
+{
+	const char *event_name = is_final_data ? "timer" : "th_timer";
+	struct strbuf buf_payload = STRBUF_INIT;
+	double t_total = ((double)timer->total_ns) / 1000000000.0;
+	double t_min = ((double)timer->min_ns) / 1000000000.0;
+	double t_max = ((double)timer->max_ns) / 1000000000.0;
+
+	strbuf_addf(&buf_payload, ("name:%s"
+				   " intervals:%"PRIu64
+				   " total:%8.6f min:%8.6f max:%8.6f"),
+		    meta->name,
+		    timer->interval_count,
+		    t_total, t_min, t_max);
+
+	perf_io_write_fl(__FILE__, __LINE__, event_name, NULL, NULL, NULL,
+			 meta->category, &buf_payload);
+	strbuf_release(&buf_payload);
+}
+
 struct tr2_tgt tr2_tgt_perf = {
 	.pdst = &tr2dst_perf,
 
@@ -586,4 +609,5 @@ struct tr2_tgt tr2_tgt_perf = {
 	.pfn_data_fl = fn_data_fl,
 	.pfn_data_json_fl = fn_data_json_fl,
 	.pfn_printf_va_fl = fn_printf_va_fl,
+	.pfn_timer = fn_timer,
 };
diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c
index 3a67532aae4..04900bb4c3a 100644
--- a/trace2/tr2_tls.c
+++ b/trace2/tr2_tls.c
@@ -181,3 +181,13 @@ int tr2tls_locked_increment(int *p)
 
 	return current_value;
 }
+
+void tr2tls_lock(void)
+{
+	pthread_mutex_lock(&tr2tls_mutex);
+}
+
+void tr2tls_unlock(void)
+{
+	pthread_mutex_unlock(&tr2tls_mutex);
+}
diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h
index e17cc462f87..2322b0d0ef0 100644
--- a/trace2/tr2_tls.h
+++ b/trace2/tr2_tls.h
@@ -2,6 +2,7 @@
 #define TR2_TLS_H
 
 #include "strbuf.h"
+#include "trace2/tr2_tmr.h"
 
 /*
  * Notice: the term "TLS" refers to "thread-local storage" in the
@@ -20,6 +21,9 @@ struct tr2tls_thread_ctx {
 	size_t alloc;
 	size_t nr_open_regions; /* plays role of "nr" in ALLOC_GROW */
 	int thread_id;
+	struct tr2_timer_block timer_block;
+	unsigned int used_any_timer:1;
+	unsigned int used_any_per_thread_timer:1;
 };
 
 /*
@@ -107,4 +111,10 @@ int tr2tls_locked_increment(int *p);
  */
 void tr2tls_start_process_clock(void);
 
+/*
+ * Explicitly lock/unlock our mutex.
+ */
+void tr2tls_lock(void);
+void tr2tls_unlock(void);
+
 #endif /* TR2_TLS_H */
diff --git a/trace2/tr2_tmr.c b/trace2/tr2_tmr.c
new file mode 100644
index 00000000000..786762dfd26
--- /dev/null
+++ b/trace2/tr2_tmr.c
@@ -0,0 +1,182 @@
+#include "cache.h"
+#include "thread-utils.h"
+#include "trace2/tr2_tgt.h"
+#include "trace2/tr2_tls.h"
+#include "trace2/tr2_tmr.h"
+
+#define MY_MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MY_MIN(a, b) ((a) < (b) ? (a) : (b))
+
+/*
+ * A global timer block to aggregate values from the partial sums from
+ * each thread.
+ */
+static struct tr2_timer_block final_timer_block; /* access under tr2tls_mutex */
+
+/*
+ * Define metadata for each stopwatch timer.
+ *
+ * This array must match "enum trace2_timer_id" and the values
+ * in "struct tr2_timer_block.timer[*]".
+ */
+static struct tr2_timer_metadata tr2_timer_metadata[TRACE2_NUMBER_OF_TIMERS] = {
+	[TRACE2_TIMER_ID_TEST1] = {
+		.category = "test",
+		.name = "test1",
+		.want_per_thread_events = 0,
+	},
+	[TRACE2_TIMER_ID_TEST2] = {
+		.category = "test",
+		.name = "test2",
+		.want_per_thread_events = 1,
+	},
+
+	/* Add additional metadata before here. */
+};
+
+void tr2_start_timer(enum trace2_timer_id tid)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	struct tr2_timer *t = &ctx->timer_block.timer[tid];
+
+	t->recursion_count++;
+	if (t->recursion_count > 1)
+		return; /* ignore recursive starts */
+
+	t->start_ns = getnanotime();
+}
+
+void tr2_stop_timer(enum trace2_timer_id tid)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	struct tr2_timer *t = &ctx->timer_block.timer[tid];
+	uint64_t ns_now;
+	uint64_t ns_interval;
+
+	assert(t->recursion_count > 0);
+
+	t->recursion_count--;
+	if (t->recursion_count)
+		return; /* still in recursive call(s) */
+
+	ns_now = getnanotime();
+	ns_interval = ns_now - t->start_ns;
+
+	t->total_ns += ns_interval;
+
+	/*
+	 * min_ns was initialized to zero (in the xcalloc()) rather
+	 * than UINT_MAX when the block of timers was allocated,
+	 * so we should always set both the min_ns and max_ns values
+	 * the first time that the timer is used.
+	 */
+	if (!t->interval_count) {
+		t->min_ns = ns_interval;
+		t->max_ns = ns_interval;
+	} else {
+		t->min_ns = MY_MIN(ns_interval, t->min_ns);
+		t->max_ns = MY_MAX(ns_interval, t->max_ns);
+	}
+
+	t->interval_count++;
+
+	ctx->used_any_timer = 1;
+	if (tr2_timer_metadata[tid].want_per_thread_events)
+		ctx->used_any_per_thread_timer = 1;
+}
+
+void tr2_update_final_timers(void)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	enum trace2_timer_id tid;
+
+	if (!ctx->used_any_timer)
+		return;
+
+	/*
+	 * Accessing `final_timer_block` requires holding `tr2tls_mutex`.
+	 * We assume that our caller is holding the lock.
+	 */
+
+	for (tid = 0; tid < TRACE2_NUMBER_OF_TIMERS; tid++) {
+		struct tr2_timer *t_final = &final_timer_block.timer[tid];
+		struct tr2_timer *t = &ctx->timer_block.timer[tid];
+
+		if (t->recursion_count) {
+			/*
+			 * The current thread is exiting with
+			 * timer[tid] still running.
+			 *
+			 * Technically, this is a bug, but I'm going
+			 * to ignore it.
+			 *
+			 * I don't think it is worth calling die()
+			 * for.  I don't think it is worth killing the
+			 * process for this bookkeeping error.  We
+			 * might want to call warning(), but I'm going
+			 * to wait on that.
+			 *
+			 * The downside here is that total_ns won't
+			 * include the current open interval (now -
+			 * start_ns).  I can live with that.
+			 */
+		}
+
+		if (!t->interval_count)
+			continue; /* this timer was not used by this thread */
+
+		t_final->total_ns += t->total_ns;
+
+		/*
+		 * final_timer_block.timer[tid].min_ns was initialized to
+		 * was initialized to zero rather than UINT_MAX, so we should
+		 * always set both the min_ns and max_ns values the first time
+		 * that we add a partial sum into it.
+		 */
+		if (!t_final->interval_count) {
+			t_final->min_ns = t->min_ns;
+			t_final->max_ns = t->max_ns;
+		} else {
+			t_final->min_ns = MY_MIN(t_final->min_ns, t->min_ns);
+			t_final->max_ns = MY_MAX(t_final->max_ns, t->max_ns);
+		}
+
+		t_final->interval_count += t->interval_count;
+	}
+}
+
+void tr2_emit_per_thread_timers(tr2_tgt_evt_timer_t *fn_apply)
+{
+	struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
+	enum trace2_timer_id tid;
+
+	if (!ctx->used_any_per_thread_timer)
+		return;
+
+	/*
+	 * For each timer, if the timer wants per-thread events and
+	 * this thread used it, emit it.
+	 */
+	for (tid = 0; tid < TRACE2_NUMBER_OF_TIMERS; tid++)
+		if (tr2_timer_metadata[tid].want_per_thread_events &&
+		    ctx->timer_block.timer[tid].interval_count)
+			fn_apply(&tr2_timer_metadata[tid],
+				 &ctx->timer_block.timer[tid],
+				 0);
+}
+
+void tr2_emit_final_timers(tr2_tgt_evt_timer_t *fn_apply)
+{
+	enum trace2_timer_id tid;
+
+	/*
+	 * Accessing `final_timer_block` requires holding `tr2tls_mutex`.
+	 * We assume that our caller is holding the lock.
+	 */
+
+	for (tid = 0; tid < TRACE2_NUMBER_OF_TIMERS; tid++)
+		if (final_timer_block.timer[tid].interval_count)
+			fn_apply(&tr2_timer_metadata[tid],
+				 &final_timer_block.timer[tid],
+				 1);
+}
diff --git a/trace2/tr2_tmr.h b/trace2/tr2_tmr.h
new file mode 100644
index 00000000000..d5753576134
--- /dev/null
+++ b/trace2/tr2_tmr.h
@@ -0,0 +1,140 @@
+#ifndef TR2_TMR_H
+#define TR2_TMR_H
+
+#include "trace2.h"
+#include "trace2/tr2_tgt.h"
+
+/*
+ * Define a mechanism to allow "stopwatch" timers.
+ *
+ * Timers can be used to measure "interesting" activity that does not
+ * fit the "region" model, such as code called from many different
+ * regions (like zlib) and/or where data for individual calls are not
+ * interesting or are too numerous to be efficiently logged.
+ *
+ * Timer values are accumulated during program execution and emitted
+ * to the Trace2 logs at program exit.
+ *
+ * To make this model efficient, we define a compile-time fixed set of
+ * timers and timer ids using a "timer block" array in thread-local
+ * storage.  This gives us constant time access to each timer within
+ * each thread, since we want start/stop operations to be as fast as
+ * possible.  This lets us avoid the complexities of dynamically
+ * allocating a timer on the first use by a thread and/or possibly
+ * sharing that timer definition with other concurrent threads.
+ * However, this does require that we define time the set of timers at
+ * compile time.
+ *
+ * Each thread uses the timer block in its thread-local storage to
+ * compute partial sums for each timer (without locking).  When a
+ * thread exits, those partial sums are (under lock) added to the
+ * global final sum.
+ *
+ * Using this "timer block" model costs ~48 bytes per timer per thread
+ * (we have about six uint64 fields per timer).  This does increase
+ * the size of the thread-local storage block, but it is allocated (at
+ * thread create time) and not on the thread stack, so I'm not worried
+ * about the size.
+ *
+ * Partial sums for each timer are optionally emitted when a thread
+ * exits.
+ *
+ * Final sums for each timer are emitted between the "exit" and
+ * "atexit" events.
+ *
+ * A parallel "timer metadata" table contains the "category" and "name"
+ * fields for each timer.  This eliminates the need to include those
+ * args in the various timer APIs.
+ */
+
+/*
+ * The definition of an individual timer and used by an individual
+ * thread.
+ */
+struct tr2_timer {
+	/*
+	 * Total elapsed time for this timer in this thread in nanoseconds.
+	 */
+	uint64_t total_ns;
+
+	/*
+	 * The maximum and minimum interval values observed for this
+	 * timer in this thread.
+	 */
+	uint64_t min_ns;
+	uint64_t max_ns;
+
+	/*
+	 * The value of the clock when this timer was started in this
+	 * thread.  (Undefined when the timer is not active in this
+	 * thread.)
+	 */
+	uint64_t start_ns;
+
+	/*
+	 * Number of times that this timer has been started and stopped
+	 * in this thread.  (Recursive starts are ignored.)
+	 */
+	uint64_t interval_count;
+
+	/*
+	 * Number of nested starts on the stack in this thread.  (We
+	 * ignore recursive starts and use this to track the recursive
+	 * calls.)
+	 */
+	unsigned int recursion_count;
+};
+
+/*
+ * Metadata for a timer.
+ */
+struct tr2_timer_metadata {
+	const char *category;
+	const char *name;
+
+	/*
+	 * True if we should emit per-thread events for this timer
+	 * when individual threads exit.
+	 */
+	unsigned int want_per_thread_events:1;
+};
+
+/*
+ * A compile-time fixed-size block of timers to insert into
+ * thread-local storage.  This wrapper is used to avoid quirks
+ * of C and the usual need to pass an array size argument.
+ */
+struct tr2_timer_block {
+	struct tr2_timer timer[TRACE2_NUMBER_OF_TIMERS];
+};
+
+/*
+ * Private routines used by trace2.c to actually start/stop an
+ * individual timer in the current thread.
+ */
+void tr2_start_timer(enum trace2_timer_id tid);
+void tr2_stop_timer(enum trace2_timer_id tid);
+
+/*
+ * Add the current thread's timer data to the global totals.
+ * This is called during thread-exit.
+ *
+ * Caller must be holding the tr2tls_mutex.
+ */
+void tr2_update_final_timers(void);
+
+/*
+ * Emit per-thread timer data for the current thread.
+ * This is called during thread-exit.
+ */
+void tr2_emit_per_thread_timers(tr2_tgt_evt_timer_t *fn_apply);
+
+/*
+ * Emit global total timer values.
+ * This is called during atexit handling.
+ *
+ * Caller must be holding the tr2tls_mutex.
+ */
+void tr2_emit_final_timers(tr2_tgt_evt_timer_t *fn_apply);
+
+#endif /* TR2_TMR_H */
