diff --git a/tools/testing/selftests/sync/Makefile b/tools/testing/selftests/sync/Makefile
index 19731b9..1ed2864 100644
--- a/tools/testing/selftests/sync/Makefile
+++ b/tools/testing/selftests/sync/Makefile
@@ -18,6 +18,7 @@ TESTS += sync_alloc.o
 TESTS += sync_fence.o
 TESTS += sync_merge.o
 TESTS += sync_wait.o
+TESTS += sync_stress_parallelism.o
 
 sync_test: $(SRC) $(TESTS)
 
diff --git a/tools/testing/selftests/sync/sync_stress_parallelism.c b/tools/testing/selftests/sync/sync_stress_parallelism.c
new file mode 100644
index 0000000..e6c9be6
--- /dev/null
+++ b/tools/testing/selftests/sync/sync_stress_parallelism.c
@@ -0,0 +1,111 @@
+/*
+ *  sync stress test: parallelism
+ *  Copyright 2015-2016 Collabora Ltd.
+ *
+ *  Based on the implementation from the Android Open Source Project,
+ *
+ *  Copyright 2012 Google, Inc
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a
+ *  copy of this software and associated documentation files (the "Software"),
+ *  to deal in the Software without restriction, including without limitation
+ *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ *  and/or sell copies of the Software, and to permit persons to whom the
+ *  Software is furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in
+ *  all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ *  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ *  OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ *  ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *  OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <pthread.h>
+
+#include "sync.h"
+#include "sw_sync.h"
+#include "synctest.h"
+
+static struct {
+	int iterations;
+	int timeline;
+	int counter;
+} test_data_two_threads;
+
+static int test_stress_two_threads_shared_timeline_thread(void *d)
+{
+	int thread_id = (long)d;
+	int timeline = test_data_two_threads.timeline;
+	int iterations = test_data_two_threads.iterations;
+	int fence, valid, ret, i;
+
+	for (i = 0; i < iterations; i++) {
+		fence = sw_sync_fence_create(timeline, "fence",
+					     i * 2 + thread_id);
+		valid = sw_sync_fence_is_valid(fence);
+		ASSERT(valid, "Failure allocating fence\n");
+
+		/* Wait on the prior thread to complete */
+		ret = sync_wait(fence, -1);
+		ASSERT(ret > 0, "Problem occurred on prior thread\n");
+
+		/*
+		 * Confirm the previous thread's writes are visible
+		 * and then increment
+		 */
+		ASSERT(test_data_two_threads.counter == i * 2 + thread_id,
+		       "Counter got damaged!\n");
+		test_data_two_threads.counter++;
+
+		/* Kick off the other thread */
+		ret = sw_sync_timeline_inc(timeline, 1);
+		ASSERT(ret == 0, "Advancing timeline failed\n");
+
+		sw_sync_fence_destroy(fence);
+	}
+
+	return 0;
+}
+
+int test_stress_two_threads_shared_timeline(void)
+{
+	pthread_t a, b;
+	int valid;
+	int timeline = sw_sync_timeline_create();
+
+	valid = sw_sync_timeline_is_valid(timeline);
+	ASSERT(valid, "Failure allocating timeline\n");
+
+	test_data_two_threads.iterations = 1 << 16;
+	test_data_two_threads.counter = 0;
+	test_data_two_threads.timeline = timeline;
+
+	/*
+	 * Use a single timeline to synchronize two threads
+	 * hammmering on the same counter.
+	 */
+
+	pthread_create(&a, NULL, (void *(*)(void *))
+		       test_stress_two_threads_shared_timeline_thread,
+		       (void *)0);
+	pthread_create(&b, NULL, (void *(*)(void *))
+		       test_stress_two_threads_shared_timeline_thread,
+		       (void *)1);
+
+	pthread_join(a, NULL);
+	pthread_join(b, NULL);
+
+	/* make sure the threads did not trample on one another */
+	ASSERT(test_data_two_threads.counter ==
+	       test_data_two_threads.iterations * 2,
+	       "Counter has unexpected value\n");
+
+	sw_sync_timeline_destroy(timeline);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/sync/sync_test.c b/tools/testing/selftests/sync/sync_test.c
index eab5ceb..3bb1024 100644
--- a/tools/testing/selftests/sync/sync_test.c
+++ b/tools/testing/selftests/sync/sync_test.c
@@ -66,6 +66,7 @@ int main(void)
 	err += RUN_TEST(test_fence_one_timeline_merge);
 	err += RUN_TEST(test_fence_merge_same_fence);
 	err += RUN_TEST(test_fence_multi_timeline_wait);
+	err += RUN_TEST(test_stress_two_threads_shared_timeline);
 
 	if (err)
 		printf("[FAIL]\tsync errors: %d\n", err);
diff --git a/tools/testing/selftests/sync/synctest.h b/tools/testing/selftests/sync/synctest.h
index 0fad57d..c461577 100644
--- a/tools/testing/selftests/sync/synctest.h
+++ b/tools/testing/selftests/sync/synctest.h
@@ -54,4 +54,7 @@ int test_fence_merge_same_fence(void);
 /* Fence wait tests */
 int test_fence_multi_timeline_wait(void);
 
+/* Stress test - parallelism */
+int test_stress_two_threads_shared_timeline(void);
+
 #endif
