diff --git a/libsync/Android.bp b/libsync/Android.bp
index 3fae5e669..c95563dff 100644
--- a/libsync/Android.bp
+++ b/libsync/Android.bp
@@ -39,13 +39,6 @@ cc_library_static {
     defaults: ["libsync_defaults"],
 }
 
-cc_test {
-    name: "sync_test",
-    defaults: ["libsync_defaults"],
-    gtest: false,
-    srcs: ["sync_test.c"],
-}
-
 cc_test {
     name: "sync-unit-tests",
     shared_libs: ["libsync"],
diff --git a/libsync/include/android/sync.h b/libsync/include/android/sync.h
index 68f74a0b2..32bb878ba 100644
--- a/libsync/include/android/sync.h
+++ b/libsync/include/android/sync.h
@@ -41,28 +41,8 @@
 
 __BEGIN_DECLS
 
-struct sync_fence_info_data {
- uint32_t len;
- char name[32];
- int32_t status;
- uint8_t pt_info[0];
-};
-
-struct sync_pt_info {
- uint32_t len;
- char obj_name[32];
- char driver_name[32];
- int32_t status;
- uint64_t timestamp_ns;
- uint8_t driver_data[0];
-};
-
 /* timeout in msecs */
 int sync_wait(int fd, int timeout);
-struct sync_fence_info_data *sync_fence_info(int fd);
-struct sync_pt_info *sync_pt_info(struct sync_fence_info_data *info,
-                                  struct sync_pt_info *itr);
-void sync_fence_info_free(struct sync_fence_info_data *info);
 
 __END_DECLS
 
diff --git a/libsync/sync.c b/libsync/sync.c
index 6b187faed..b8c48c7f7 100644
--- a/libsync/sync.c
+++ b/libsync/sync.c
@@ -30,6 +30,29 @@
 
 #include <android/sync.h>
 
+/* Prototypes for deprecated functions that used to be declared in the legacy
+ * android/sync.h. They've been moved here to make sure new code does not use
+ * them, but the functions are still defined to avoid breaking existing
+ * binaries. Eventually they can be removed altogether.
+ */
+struct sync_fence_info_data {
+    uint32_t len;
+    char name[32];
+    int32_t status;
+    uint8_t pt_info[0];
+};
+struct sync_pt_info {
+    uint32_t len;
+    char obj_name[32];
+    char driver_name[32];
+    int32_t status;
+    uint64_t timestamp_ns;
+    uint8_t driver_data[0];
+};
+struct sync_fence_info_data* sync_fence_info(int fd);
+struct sync_pt_info* sync_pt_info(struct sync_fence_info_data* info, struct sync_pt_info* itr);
+void sync_fence_info_free(struct sync_fence_info_data* info);
+
 /* Legacy Sync API */
 
 struct sync_legacy_merge_data {
diff --git a/libsync/sync_test.c b/libsync/sync_test.c
deleted file mode 100644
index f1ffdcf9e..000000000
--- a/libsync/sync_test.c
+++ /dev/null
@@ -1,147 +0,0 @@
-/*
- *  sync_test.c
- *
- *   Copyright 2012 Google, Inc
- *
- *  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 <errno.h>
-#include <pthread.h>
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
-
-#include <android/sync.h>
-#include "sw_sync.h"
-
-pthread_mutex_t printf_mutex = PTHREAD_MUTEX_INITIALIZER;
-
-struct sync_thread_data {
-    int thread_no;
-    int fd[2];
-};
-
-void *sync_thread(void *data)
-{
-    struct sync_thread_data *sync_data = data;
-    struct sync_fence_info_data *info;
-    int err;
-    int i;
-
-    for (i = 0; i < 2; i++) {
-        err = sync_wait(sync_data->fd[i], 10000);
-
-        pthread_mutex_lock(&printf_mutex);
-        if (err < 0) {
-            printf("thread %d wait %d failed: %s\n", sync_data->thread_no,
-                   i, strerror(errno));
-        } else {
-            printf("thread %d wait %d done\n", sync_data->thread_no, i);
-        }
-        info = sync_fence_info(sync_data->fd[i]);
-        if (info) {
-            struct sync_pt_info *pt_info = NULL;
-            printf("  fence %s %d\n", info->name, info->status);
-
-            while ((pt_info = sync_pt_info(info, pt_info))) {
-                int ts_sec = pt_info->timestamp_ns / 1000000000LL;
-                int ts_usec = (pt_info->timestamp_ns % 1000000000LL) / 1000LL;
-                printf("    pt %s %s %d %d.%06d", pt_info->obj_name,
-                       pt_info->driver_name, pt_info->status,
-                       ts_sec, ts_usec);
-                if (!strcmp(pt_info->driver_name, "sw_sync"))
-                    printf(" val=%d\n", *(uint32_t *)pt_info->driver_data);
-                else
-                    printf("\n");
-            }
-            sync_fence_info_free(info);
-        }
-        pthread_mutex_unlock(&printf_mutex);
-    }
-
-    return NULL;
-}
-
-int main(int argc __attribute__((unused)), char *argv[] __attribute__((unused)))
-{
-    struct sync_thread_data sync_data[4];
-    pthread_t threads[4];
-    int sync_timeline_fd;
-    int i, j;
-    char str[256];
-
-    sync_timeline_fd = sw_sync_timeline_create();
-    if (sync_timeline_fd < 0) {
-        perror("can't create sw_sync_timeline:");
-        return 1;
-    }
-
-    for (i = 0; i < 3; i++) {
-        sync_data[i].thread_no = i;
-
-        for (j = 0; j < 2; j++) {
-            unsigned val = i + j * 3 + 1;
-            snprintf(str, sizeof(str), "test_fence%d-%d", i, j);
-            int fd = sw_sync_fence_create(sync_timeline_fd, str, val);
-            if (fd < 0) {
-                printf("can't create sync pt %d: %s", val, strerror(errno));
-                return 1;
-            }
-            sync_data[i].fd[j] = fd;
-            printf("sync_data[%d].fd[%d] = %d;\n", i, j, fd);
-
-        }
-    }
-
-    sync_data[3].thread_no = 3;
-    for (j = 0; j < 2; j++) {
-        snprintf(str, sizeof(str), "merged_fence%d", j);
-        sync_data[3].fd[j] = sync_merge(str, sync_data[0].fd[j], sync_data[1].fd[j]);
-        if (sync_data[3].fd[j] < 0) {
-            printf("can't merge sync pts %d and %d: %s\n",
-                   sync_data[0].fd[j], sync_data[1].fd[j], strerror(errno));
-            return 1;
-        }
-    }
-
-    for (i = 0; i < 4; i++)
-        pthread_create(&threads[i], NULL, sync_thread, &sync_data[i]);
-
-
-    for (i = 0; i < 3; i++) {
-        int err;
-        printf("press enter to inc to %d\n", i+1);
-        fgets(str, sizeof(str), stdin);
-        err = sw_sync_timeline_inc(sync_timeline_fd, 1);
-        if (err < 0) {
-            perror("can't increment sync obj:");
-            return 1;
-        }
-    }
-
-    printf("press enter to close sync_timeline\n");
-    fgets(str, sizeof(str), stdin);
-
-    close(sync_timeline_fd);
-
-    printf("press enter to end test\n");
-    fgets(str, sizeof(str), stdin);
-
-    for (i = 0; i < 3; i++) {
-        void *val;
-        pthread_join(threads[i], &val);
-    }
-
-    return 0;
-}
diff --git a/libsync/tests/sync_test.cpp b/libsync/tests/sync_test.cpp
index 0fb86d6fc..011b09d00 100644
--- a/libsync/tests/sync_test.cpp
+++ b/libsync/tests/sync_test.cpp
@@ -15,6 +15,35 @@
 #include <random>
 #include <unordered_map>
 
+/* These deprecated declarations were in the legacy android/sync.h. They've been removed to
+ * encourage code to move to the modern equivalents. But they are still implemented in libsync.so
+ * to avoid breaking existing binaries; as long as that's true we should keep testing them here.
+ * That means making local copies of the declarations.
+ */
+extern "C" {
+
+struct sync_fence_info_data {
+    uint32_t len;
+    char name[32];
+    int32_t status;
+    uint8_t pt_info[0];
+};
+
+struct sync_pt_info {
+    uint32_t len;
+    char obj_name[32];
+    char driver_name[32];
+    int32_t status;
+    uint64_t timestamp_ns;
+    uint8_t driver_data[0];
+};
+
+struct sync_fence_info_data* sync_fence_info(int fd);
+struct sync_pt_info* sync_pt_info(struct sync_fence_info_data* info, struct sync_pt_info* itr);
+void sync_fence_info_free(struct sync_fence_info_data* info);
+
+}  // extern "C"
+
 // 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.