diff --git a/libsync/tests/Android.mk b/libsync/tests/Android.mk
new file mode 100644
index 0000000..ad20e50
--- /dev/null
+++ b/libsync/tests/Android.mk
@@ -0,0 +1,31 @@
+#
+# Copyright 2014 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.
+#
+
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+include external/libcxx/libcxx.mk
+LOCAL_CLANG := true
+LOCAL_MODULE := sync-unit-tests
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
+LOCAL_CFLAGS += -g -Wall -Werror -std=gnu++11 -Wno-missing-field-initializers -Wno-sign-compare
+LOCAL_SHARED_LIBRARIES += libsync
+LOCAL_STATIC_LIBRARIES += libgtest_main
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/../include
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/..
+LOCAL_SRC_FILES := \
+    sync_test.cpp
+include $(BUILD_NATIVE_TEST)
diff --git a/libsync/tests/sync_test.cpp b/libsync/tests/sync_test.cpp
new file mode 100644
index 0000000..55cd687
--- /dev/null
+++ b/libsync/tests/sync_test.cpp
@@ -0,0 +1,615 @@
+#include <gtest/gtest.h>
+#include <sync/sync.h>
+#include <sw_sync.h>
+#include <fcntl.h>
+#include <vector>
+#include <string>
+#include <cassert>
+#include <iostream>
+#include <unistd.h>
+#include <thread>
+#include <poll.h>
+#include <mutex>
+#include <algorithm>
+#include <tuple>
+#include <random>
+#include <unordered_map>
+
+// TODO: better stress tests?
+// Handle more than 64 fd's simultaneously, i.e. fix sync_fence_info's 4k limit.
+// Handle wraparound in timelines like nvidia.
+
+using namespace std;
+
+namespace {
+
+// C++ wrapper class for sync timeline.
+class SyncTimeline {
+    int m_fd = -1;
+    bool m_fdInitialized = false;
+public:
+    SyncTimeline(const SyncTimeline &) = delete;
+    SyncTimeline& operator=(SyncTimeline&) = delete;
+    SyncTimeline() noexcept {
+        int fd = sw_sync_timeline_create();
+        if (fd == -1)
+            return;
+        m_fdInitialized = true;
+        m_fd = fd;
+    }
+    void destroy() {
+        if (m_fdInitialized) {
+            close(m_fd);
+            m_fd = -1;
+            m_fdInitialized = false;
+        }
+    }
+    ~SyncTimeline() {
+        destroy();
+    }
+    bool isValid() const {
+        if (m_fdInitialized) {
+            int status = fcntl(m_fd, F_GETFD, 0);
+            if (status == 0)
+                return true;
+            else
+                return false;
+        }
+        else {
+            return false;
+        }
+    }
+    int getFd() const {
+        return m_fd;
+    }
+    int inc(int val = 1) {
+        return sw_sync_timeline_inc(m_fd, val);
+    }
+};
+
+struct SyncPointInfo {
+    std::string driverName;
+    std::string objectName;
+    uint64_t timeStampNs;
+    int status; // 1 sig, 0 active, neg is err
+};
+
+// Wrapper class for sync fence.
+class SyncFence {
+    int m_fd = -1;
+    bool m_fdInitialized = false;
+    static int s_fenceCount;
+
+    void setFd(int fd) {
+        m_fd = fd;
+        m_fdInitialized = true;
+    }
+    void clearFd() {
+        m_fd = -1;
+        m_fdInitialized = false;
+    }
+public:
+    bool isValid() const {
+        if (m_fdInitialized) {
+            int status = fcntl(m_fd, F_GETFD, 0);
+            if (status == 0)
+                return true;
+            else
+                return false;
+        }
+        else {
+            return false;
+        }
+    }
+    SyncFence& operator=(SyncFence &&rhs) noexcept {
+        destroy();
+        if (rhs.isValid()) {
+            setFd(rhs.getFd());
+            rhs.clearFd();
+        }
+        return *this;
+    }
+    SyncFence(SyncFence &&fence) noexcept {
+        if (fence.isValid()) {
+            setFd(fence.getFd());
+            fence.clearFd();
+        }
+    }
+    SyncFence(const SyncFence &fence) noexcept {
+        // This is ok, as sync fences are immutable after construction, so a dup
+        // is basically the same thing as a copy.
+        if (fence.isValid()) {
+            int fd = dup(fence.getFd());
+            if (fd == -1)
+                return;
+            setFd(fd);
+        }
+    }
+    SyncFence(const SyncTimeline &timeline,
+              int value,
+              const char *name = nullptr) noexcept {
+        std::string autoName = "allocFence";
+        autoName += s_fenceCount;
+        s_fenceCount++;
+        int fd = sw_sync_fence_create(timeline.getFd(), name ? name : autoName.c_str(), value);
+        if (fd == -1)
+            return;
+        setFd(fd);
+    }
+    SyncFence(const SyncFence &a, const SyncFence &b, const char *name = nullptr) noexcept {
+        std::string autoName = "mergeFence";
+        autoName += s_fenceCount;
+        s_fenceCount++;
+        int fd = sync_merge(name ? name : autoName.c_str(), a.getFd(), b.getFd());
+        if (fd == -1)
+            return;
+        setFd(fd);
+    }
+    SyncFence(const vector<SyncFence> &sources) noexcept {
+        assert(sources.size());
+        SyncFence temp(*begin(sources));
+        for (auto itr = ++begin(sources); itr != end(sources); ++itr) {
+            temp = SyncFence(*itr, temp);
+        }
+        if (temp.isValid()) {
+            setFd(temp.getFd());
+            temp.clearFd();
+        }
+    }
+    void destroy() {
+        if (isValid()) {
+            close(m_fd);
+            clearFd();
+        }
+    }
+    ~SyncFence() {
+        destroy();
+    }
+    int getFd() const {
+        return m_fd;
+    }
+    int wait(int timeout = -1) {
+        return sync_wait(m_fd, timeout);
+    }
+    vector<SyncPointInfo> getInfo() const {
+        struct sync_pt_info *pointInfo = nullptr;
+        vector<SyncPointInfo> fenceInfo;
+        sync_fence_info_data *info = sync_fence_info(getFd());
+        if (!info) {
+            return fenceInfo;
+        }
+        while ((pointInfo = sync_pt_info(info, pointInfo))) {
+            fenceInfo.push_back(SyncPointInfo{
+                pointInfo->driver_name,
+                pointInfo->obj_name,
+                pointInfo->timestamp_ns,
+                pointInfo->status});
+        }
+        sync_fence_info_free(info);
+        return fenceInfo;
+    }
+    int getSize() const {
+        return getInfo().size();
+    }
+    int getSignaledCount() const {
+        return countWithStatus(1);
+    }
+    int getActiveCount() const {
+        return countWithStatus(0);
+    }
+    int getErrorCount() const {
+        return countWithStatus(-1);
+    }
+private:
+    int countWithStatus(int status) const {
+        int count = 0;
+        for (auto &info : getInfo()) {
+            if (info.status == status) {
+                count++;
+            }
+        }
+        return count;
+    }
+};
+
+int SyncFence::s_fenceCount = 0;
+
+TEST(AllocTest, Timeline) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+}
+
+TEST(AllocTest, Fence) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fence(timeline, 1);
+    ASSERT_TRUE(fence.isValid());
+}
+
+TEST(AllocTest, FenceNegative) {
+    int timeline = sw_sync_timeline_create();
+    ASSERT_GT(timeline, 0);
+
+    // bad fd.
+    ASSERT_LT(sw_sync_fence_create(-1, "fence", 1), 0);
+
+    // No name - segfaults in user space.
+    // Maybe we should be friendlier here?
+    /*
+    ASSERT_LT(sw_sync_fence_create(timeline, nullptr, 1), 0);
+    */
+    close(timeline);
+}
+
+TEST(FenceTest, OneTimelineWait) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fence(timeline, 5);
+    ASSERT_TRUE(fence.isValid());
+
+    // Wait on fence until timeout.
+    ASSERT_EQ(fence.wait(0), -1);
+    ASSERT_EQ(errno, ETIME);
+
+    // Advance timeline from 0 -> 1
+    ASSERT_EQ(timeline.inc(1), 0);
+
+    // Wait on fence until timeout.
+    ASSERT_EQ(fence.wait(0), -1);
+    ASSERT_EQ(errno, ETIME);
+
+    // Signal the fence.
+    ASSERT_EQ(timeline.inc(4), 0);
+
+    // Wait successfully.
+    ASSERT_EQ(fence.wait(0), 0);
+
+    // Go even futher, and confirm wait still succeeds.
+    ASSERT_EQ(timeline.inc(10), 0);
+    ASSERT_EQ(fence.wait(0), 0);
+}
+
+TEST(FenceTest, OneTimelinePoll) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fence(timeline, 100);
+    ASSERT_TRUE(fence.isValid());
+
+    fd_set set;
+    FD_ZERO(&set);
+    FD_SET(fence.getFd(), &set);
+
+    // Poll the fence, and wait till timeout.
+    timeval time = {0};
+    ASSERT_EQ(select(fence.getFd() + 1, &set, nullptr, nullptr, &time), 0);
+
+    // Advance the timeline.
+    timeline.inc(100);
+    timeline.inc(100);
+
+    // Select should return that the fd is read for reading.
+    FD_ZERO(&set);
+    FD_SET(fence.getFd(), &set);
+
+    ASSERT_EQ(select(fence.getFd() + 1, &set, nullptr, nullptr, &time), 1);
+    ASSERT_TRUE(FD_ISSET(fence.getFd(), &set));
+}
+
+TEST(FenceTest, OneTimelineMerge) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    // create fence a,b,c and then merge them all into fence d.
+    SyncFence a(timeline, 1), b(timeline, 2), c(timeline, 3);
+    ASSERT_TRUE(a.isValid());
+    ASSERT_TRUE(b.isValid());
+    ASSERT_TRUE(c.isValid());
+
+    SyncFence d({a,b,c});
+    ASSERT_TRUE(d.isValid());
+
+    // confirm all fences have one active point (even d).
+    ASSERT_EQ(a.getActiveCount(), 1);
+    ASSERT_EQ(b.getActiveCount(), 1);
+    ASSERT_EQ(c.getActiveCount(), 1);
+    ASSERT_EQ(d.getActiveCount(), 1);
+
+    // confirm that d is not signaled until the max of a,b,c
+    timeline.inc(1);
+    ASSERT_EQ(a.getSignaledCount(), 1);
+    ASSERT_EQ(d.getActiveCount(), 1);
+
+    timeline.inc(1);
+    ASSERT_EQ(b.getSignaledCount(), 1);
+    ASSERT_EQ(d.getActiveCount(), 1);
+
+    timeline.inc(1);
+    ASSERT_EQ(c.getSignaledCount(), 1);
+    ASSERT_EQ(d.getActiveCount(), 0);
+    ASSERT_EQ(d.getSignaledCount(), 1);
+}
+
+TEST(FenceTest, MergeSameFence) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fence(timeline, 5);
+    ASSERT_TRUE(fence.isValid());
+
+    SyncFence selfMergeFence(fence, fence);
+    ASSERT_TRUE(selfMergeFence.isValid());
+
+    ASSERT_EQ(selfMergeFence.getSignaledCount(), 0);
+
+    timeline.inc(5);
+    ASSERT_EQ(selfMergeFence.getSignaledCount(), 1);
+}
+
+TEST(FenceTest, WaitOnDestroyedTimeline) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fenceSig(timeline, 100);
+    SyncFence fenceKill(timeline, 200);
+
+    // Spawn a thread to wait on a fence when the timeline is killed.
+    thread waitThread{
+        [&]() {
+            ASSERT_EQ(timeline.inc(100), 0);
+
+            ASSERT_EQ(fenceKill.wait(-1), -1);
+            ASSERT_EQ(errno, ENOENT);
+        }
+    };
+
+    // Wait for the thread to spool up.
+    fenceSig.wait();
+
+    // Kill the timeline.
+    timeline.destroy();
+
+    // wait for the thread to clean up.
+    waitThread.join();
+}
+
+TEST(FenceTest, PollOnDestroyedTimeline) {
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    SyncFence fenceSig(timeline, 100);
+    SyncFence fenceKill(timeline, 200);
+
+    // Spawn a thread to wait on a fence when the timeline is killed.
+    thread waitThread{
+        [&]() {
+            ASSERT_EQ(timeline.inc(100), 0);
+
+            // Wait on the fd.
+            struct pollfd fds;
+            fds.fd = fenceKill.getFd();
+            fds.events = POLLIN | POLLERR;
+            ASSERT_EQ(poll(&fds, 1, -1), 1);
+            ASSERT_TRUE(fds.revents & POLLERR);
+        }
+    };
+
+    // Wait for the thread to spool up.
+    fenceSig.wait();
+
+    // Kill the timeline.
+    timeline.destroy();
+
+    // wait for the thread to clean up.
+    waitThread.join();
+}
+
+TEST(FenceTest, MultiTimelineWait) {
+    SyncTimeline timelineA, timelineB, timelineC;
+
+    SyncFence fenceA(timelineA, 5);
+    SyncFence fenceB(timelineB, 5);
+    SyncFence fenceC(timelineC, 5);
+
+    // Make a larger fence using 3 other fences from different timelines.
+    SyncFence mergedFence({fenceA, fenceB, fenceC});
+    ASSERT_TRUE(mergedFence.isValid());
+
+    // Confirm fence isn't signaled
+    ASSERT_EQ(mergedFence.getActiveCount(), 3);
+    ASSERT_EQ(mergedFence.wait(0), -1);
+    ASSERT_EQ(errno, ETIME);
+
+    timelineA.inc(5);
+    ASSERT_EQ(mergedFence.getActiveCount(), 2);
+    ASSERT_EQ(mergedFence.getSignaledCount(), 1);
+
+    timelineB.inc(5);
+    ASSERT_EQ(mergedFence.getActiveCount(), 1);
+    ASSERT_EQ(mergedFence.getSignaledCount(), 2);
+
+    timelineC.inc(5);
+    ASSERT_EQ(mergedFence.getActiveCount(), 0);
+    ASSERT_EQ(mergedFence.getSignaledCount(), 3);
+
+    // confirm you can successfully wait.
+    ASSERT_EQ(mergedFence.wait(100), 0);
+}
+
+TEST(StressTest, TwoThreadsSharedTimeline) {
+    const int iterations = 1 << 16;
+    int counter = 0;
+    SyncTimeline timeline;
+    ASSERT_TRUE(timeline.isValid());
+
+    // Use a single timeline to synchronize two threads
+    // hammmering on the same counter.
+    auto threadMain = [&](int threadId) {
+        for (int i = 0; i < iterations; i++) {
+            SyncFence fence(timeline, i * 2 + threadId);
+            ASSERT_TRUE(fence.isValid());
+
+            // Wait on the prior thread to complete.
+            ASSERT_EQ(fence.wait(), 0);
+
+            // Confirm the previous thread's writes are visible and then inc.
+            ASSERT_EQ(counter, i * 2 + threadId);
+            counter++;
+
+            // Kick off the other thread.
+            ASSERT_EQ(timeline.inc(), 0);
+        }
+    };
+
+    thread a{threadMain, 0};
+    thread b{threadMain, 1};
+    a.join();
+    b.join();
+
+    // make sure the threads did not trample on one another.
+    ASSERT_EQ(counter, iterations * 2);
+}
+
+class ConsumerStressTest : public ::testing::TestWithParam<int> {};
+
+TEST_P(ConsumerStressTest, MultiProducerSingleConsumer) {
+    mutex lock;
+    int counter = 0;
+    int iterations = 1 << 12;
+
+    vector<SyncTimeline> producerTimelines(GetParam());
+    vector<thread> threads;
+    SyncTimeline consumerTimeline;
+
+    // Producer threads run this lambda.
+    auto threadMain = [&](int threadId) {
+        for (int i = 0; i < iterations; i++) {
+            SyncFence fence(consumerTimeline, i);
+            ASSERT_TRUE(fence.isValid());
+
+            // Wait for the consumer to finish. Use alternate
+            // means of waiting on the fence.
+            if ((iterations + threadId) % 8 != 0) {
+                ASSERT_EQ(fence.wait(), 0);
+            }
+            else {
+                while (fence.getSignaledCount() != 1) {
+                    ASSERT_EQ(fence.getErrorCount(), 0);
+                }
+            }
+
+            // Every producer increments the counter, the consumer checks + erases it.
+            lock.lock();
+            counter++;
+            lock.unlock();
+
+            ASSERT_EQ(producerTimelines[threadId].inc(), 0);
+        }
+    };
+
+    for (int i = 0; i < GetParam(); i++) {
+        threads.push_back(thread{threadMain, i});
+    }
+
+    // Consumer thread runs this loop.
+    for (int i = 1; i <= iterations; i++) {
+        // Create a fence representing all producers final timelines.
+        vector<SyncFence> fences;
+        for (auto& timeline : producerTimelines) {
+            fences.push_back(SyncFence(timeline, i));
+        }
+        SyncFence mergeFence(fences);
+        ASSERT_TRUE(mergeFence.isValid());
+
+        // Make sure we see an increment from every producer thread. Vary
+        // the means by which we wait.
+        if (iterations % 8 != 0) {
+            ASSERT_EQ(mergeFence.wait(), 0);
+        }
+        else {
+            while (mergeFence.getSignaledCount() != mergeFence.getSize()) {
+                ASSERT_EQ(mergeFence.getErrorCount(), 0);
+            }
+        }
+        ASSERT_EQ(counter, GetParam()*i);
+
+        // Release the producer threads.
+        ASSERT_EQ(consumerTimeline.inc(), 0);
+    }
+
+    for_each(begin(threads), end(threads), [](thread& thread) { thread.join(); });
+}
+INSTANTIATE_TEST_CASE_P(
+    ParameterizedStressTest,
+    ConsumerStressTest,
+    ::testing::Values(2,4,16));
+
+class MergeStressTest : public ::testing::TestWithParam<tuple<int, int>> {};
+
+template <typename K, typename V> using dict = unordered_map<K,V>;
+
+TEST_P(MergeStressTest, RandomMerge) {
+    int timelineCount = get<0>(GetParam());
+    int mergeCount = get<1>(GetParam());
+
+    vector<SyncTimeline> timelines(timelineCount);
+
+    default_random_engine generator;
+    uniform_int_distribution<int> timelineDist(0, timelines.size()-1);
+    uniform_int_distribution<int> syncPointDist(0, numeric_limits<int>::max());
+
+    SyncFence fence(timelines[0], 0);
+    ASSERT_TRUE(fence.isValid());
+
+    unordered_map<int, int> fenceMap;
+    fenceMap.insert(make_tuple(0, 0));
+
+    // Randomly create syncpoints out of a fixed set of timelines, and merge them together.
+    for (int i = 0; i < mergeCount; i++) {
+
+        // Generate syncpoint.
+        int timelineOffset = timelineDist(generator);
+        const SyncTimeline& timeline = timelines[timelineOffset];
+        int syncPoint = syncPointDist(generator);
+
+        // Keep track of the latest syncpoint in each timeline.
+        auto itr = fenceMap.find(timelineOffset);
+        if (itr == end(fenceMap)) {
+            fenceMap.insert(tie(timelineOffset, syncPoint));
+        }
+        else {
+            int oldSyncPoint = itr->second;
+            fenceMap.erase(itr);
+            fenceMap.insert(tie(timelineOffset, max(syncPoint, oldSyncPoint)));
+        }
+
+        // Merge.
+        fence = SyncFence(fence, SyncFence(timeline, syncPoint));
+        ASSERT_TRUE(fence.isValid());
+    }
+
+    // Confirm our map matches the fence.
+    ASSERT_EQ(fence.getSize(), fenceMap.size());
+
+    // Trigger the merged fence.
+    for (auto& item: fenceMap) {
+        ASSERT_EQ(fence.wait(0), -1);
+        ASSERT_EQ(errno, ETIME);
+
+        // Increment the timeline to the last syncpoint.
+        timelines[item.first].inc(item.second);
+    }
+
+    // Check that the fence is triggered.
+    ASSERT_EQ(fence.wait(0), 0);
+}
+
+INSTANTIATE_TEST_CASE_P(
+    ParameterizedMergeStressTest,
+    MergeStressTest,
+    ::testing::Combine(::testing::Values(16,32), ::testing::Values(32, 1024, 1024*32)));
+
+}
+