diff --git a/block.c b/block.c
index f9ffca4..a9767de 100644
--- a/block.c
+++ b/block.c
@@ -2613,12 +2613,15 @@ typedef struct BlkIntermediateStates {
  *
  * base <- active
  *
+ * If backing_file_str is non-NULL, it will be used when modifying top's
+ * overlay image metadata.
+ *
  * Error conditions:
  *  if active == top, that is considered an error
  *
  */
 int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
-                           BlockDriverState *base)
+                           BlockDriverState *base, const char *backing_file_str)
 {
     BlockDriverState *intermediate;
     BlockDriverState *base_bs = NULL;
@@ -2670,7 +2673,8 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
     }
 
     /* success - we can delete the intermediate states, and link top->base */
-    ret = bdrv_change_backing_file(new_top_bs, base_bs->filename,
+    backing_file_str = backing_file_str ? backing_file_str : base_bs->filename;
+    ret = bdrv_change_backing_file(new_top_bs, backing_file_str,
                                    base_bs->drv ? base_bs->drv->format_name : "");
     if (ret) {
         goto exit;
diff --git a/block/commit.c b/block/commit.c
index 5c09f44..91517d3 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -37,6 +37,7 @@ typedef struct CommitBlockJob {
     BlockdevOnError on_error;
     int base_flags;
     int orig_overlay_flags;
+    char *backing_file_str;
 } CommitBlockJob;
 
 static int coroutine_fn commit_populate(BlockDriverState *bs,
@@ -141,7 +142,7 @@ wait:
 
     if (!block_job_is_cancelled(&s->common) && sector_num == end) {
         /* success */
-        ret = bdrv_drop_intermediate(active, top, base);
+        ret = bdrv_drop_intermediate(active, top, base, s->backing_file_str);
     }
 
 exit_free_buf:
@@ -158,7 +159,7 @@ exit_restore_reopen:
     if (overlay_bs && s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
         bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
     }
-
+    g_free(s->backing_file_str);
     block_job_completed(&s->common, ret);
 }
 
@@ -182,7 +183,7 @@ static const BlockJobDriver commit_job_driver = {
 void commit_start(BlockDriverState *bs, BlockDriverState *base,
                   BlockDriverState *top, int64_t speed,
                   BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
-                  void *opaque, Error **errp)
+                  void *opaque, const char *backing_file_str, Error **errp)
 {
     CommitBlockJob *s;
     BlockReopenQueue *reopen_queue = NULL;
@@ -244,6 +245,8 @@ void commit_start(BlockDriverState *bs, BlockDriverState *base,
     s->base_flags          = orig_base_flags;
     s->orig_overlay_flags  = orig_overlay_flags;
 
+    s->backing_file_str = g_strdup(backing_file_str);
+
     s->on_error = on_error;
     s->common.co = qemu_coroutine_create(commit_run);
 
diff --git a/blockdev.c b/blockdev.c
index 44f0cc4..7a1c966 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1914,6 +1914,7 @@ void qmp_block_commit(const char *device,
                       bool has_base_node_name, const char *base_node_name,
                       bool has_top, const char *top,
                       bool has_top_node_name, const char *top_node_name,
+                      bool has_backing_file, const char *backing_file,
                       bool has_speed, int64_t speed,
                       Error **errp)
 {
@@ -2015,11 +2016,16 @@ void qmp_block_commit(const char *device,
     }
 
     if (top_bs == bs) {
+        if (has_backing_file) {
+            error_setg(errp, "'backing-file' specified,"
+                             " but 'top' is the active layer");
+            return;
+        }
         commit_active_start(bs, base_bs, speed, on_error, block_job_cb,
                             bs, &local_err);
     } else {
         commit_start(bs, base_bs, top_bs, speed, on_error, block_job_cb, bs,
-                    &local_err);
+                     has_backing_file ? backing_file : NULL, &local_err);
     }
     if (local_err != NULL) {
         error_propagate(errp, local_err);
diff --git a/include/block/block.h b/include/block/block.h
index c60bd52..2571945 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -288,7 +288,8 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt);
 void bdrv_register(BlockDriver *bdrv);
 int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
-                           BlockDriverState *base);
+                           BlockDriverState *base,
+                           const char *backing_file_str);
 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
                                     BlockDriverState *bs);
 BlockDriverState *bdrv_find_base(BlockDriverState *bs);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 7aa2213..d7d53fc 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -462,13 +462,14 @@ void stream_start(BlockDriverState *bs, BlockDriverState *base,
  * @on_error: The action to take upon error.
  * @cb: Completion function for the job.
  * @opaque: Opaque pointer value passed to @cb.
+ * @backing_file_str: String to use as the backing file in @top's overlay
  * @errp: Error object.
  *
  */
 void commit_start(BlockDriverState *bs, BlockDriverState *base,
                  BlockDriverState *top, int64_t speed,
                  BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
-                 void *opaque, Error **errp);
+                 void *opaque, const char *backing_file_str, Error **errp);
 /**
  * commit_active_start:
  * @bs: Active block device to be committed.
diff --git a/qapi/block-core.json b/qapi/block-core.json
index dddaa13..ae1dde9 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -709,6 +709,23 @@
 #                           topmost data to be committed down.
 #                           (Since 2.1)
 #
+# @backing-file:  #optional The backing file string to write into the overlay
+#                           image of 'top'.  If 'top' is the active layer,
+#                           specifying a backing file string is an error. This
+#                           filename is not validated.
+#
+#                           If a pathname string is such that it cannot be
+#                           resolved by QEMU, that means that subsequent QMP or
+#                           HMP commands must use node-names for the image in
+#                           question, as filename lookup methods will fail.
+#
+#                           If not specified, QEMU will automatically determine
+#                           the backing file string to use, or error out if
+#                           there is no obvious choice. Care should be taken
+#                           when specifying the string, to specify a valid
+#                           filename or protocol.
+#                           (Since 2.1)
+#
 #                    If top == base, that is an error.
 #                    If top == active, the job will not be completed by itself,
 #                    user needs to complete the job with the block-job-complete
@@ -721,7 +738,6 @@
 #                    size of the smaller top, you can safely truncate it
 #                    yourself once the commit operation successfully completes.
 #
-#
 # @speed:  #optional the maximum speed, in bytes per second
 #
 # Returns: Nothing on success
@@ -732,13 +748,16 @@
 #          If @speed is invalid, InvalidParameter
 #          If both @base and @base-node-name are specified, GenericError
 #          If both @top and @top-node-name are specified, GenericError
+#          If @top or @top-node-name is the active layer, and @backing-file is
+#             specified, GenericError
 #
 # Since: 1.3
 #
 ##
 { 'command': 'block-commit',
   'data': { 'device': 'str', '*base': 'str', '*base-node-name': 'str',
-            '*top': 'str', '*top-node-name': 'str', '*speed': 'int' } }
+            '*top': 'str', '*top-node-name': 'str', '*backing-file': 'str',
+            '*speed': 'int' } }
 
 ##
 # @drive-backup
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 52af928..7eb90a9 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -985,7 +985,7 @@ EQMP
 
     {
         .name       = "block-commit",
-        .args_type  = "device:B,base:s?,base-node-name:s?,top:s?,top-node-name:s?,speed:o?",
+        .args_type  = "device:B,base:s?,base-node-name:s?,top:s?,top-node-name:s?,backing-file:s?,speed:o?",
         .mhandler.cmd_new = qmp_marshal_input_block_commit,
     },
 
@@ -1021,6 +1021,23 @@ neither is specified, this is the active layer
                     topmost data to be committed down.
                     (json-string, optional) (Since 2.1)
 
+- backing-file:     The backing file string to write into the overlay
+                    image of 'top'.  If 'top' is the active layer,
+                    specifying a backing file string is an error. This
+                    filename is not validated.
+
+                    If a pathname string is such that it cannot be
+                    resolved by QEMU, that means that subsequent QMP or
+                    HMP commands must use node-names for the image in
+                    question, as filename lookup methods will fail.
+
+                    If not specified, QEMU will automatically determine
+                    the backing file string to use, or error out if
+                    there is no obvious choice. Care should be taken
+                    when specifying the string, to specify a valid
+                    filename or protocol.
+                    (json-string, optional) (Since 2.1)
+
           If top == base, that is an error.
           If top == active, the job will not be completed by itself,
           user needs to complete the job with the block-job-complete
