diff --git a/v2v/test-harness/v2v_test_harness.ml b/v2v/test-harness/v2v_test_harness.ml
index efbda7b28..f10ff983f 100644
--- a/v2v/test-harness/v2v_test_harness.ml
+++ b/v2v/test-harness/v2v_test_harness.ml
@@ -26,6 +26,7 @@ open Printf
 open Common_utils
 
 type test_plan = {
+  guest_clock : float option;
   post_conversion_test : (Guestfs.guestfs -> string -> Xml.doc -> unit) option;
   boot_plan : boot_plan;
 
@@ -42,7 +43,15 @@ and boot_plan =
 | Boot_to_idle
 | Boot_to_screenshot of string
 
+let new_year's_day year =
+  let tm = { tm_sec = 0; tm_min = 0; tm_hour = 0;
+             tm_mday = 1; tm_mon = 0; tm_year = year - 1900;
+             tm_wday = 0; tm_yday = 0; tm_isdst = false } in
+  let t, _ = mktime tm in
+  Some t
+
 let default_plan = {
+  guest_clock = None;
   post_conversion_test = None;
   boot_plan = Boot_to_idle;
   boot_wait_to_write = 120;
@@ -119,6 +128,32 @@ let run ~test ?input_disk ?input_xml ?(test_plan = default_plan) () =
           Xml.node_set_content node "2097152"
     ) nodes;
 
+    (* Adjust the <clock/> if requested. *)
+    (match test_plan.guest_clock with
+     | None -> ()
+     | Some t ->
+        let adjustment = t -. time () in
+        assert (adjustment <= 0.);
+        let adjustment = int_of_float adjustment in
+        let xpath = Xml.xpath_eval_expression xpathctx "/domain/clock" in
+        let nodes = nodes_of_xpathobj boot_xml_doc xpath in
+        let clock_node =
+          match nodes with
+          | [] ->
+             (* No <clock> element, so insert one. *)
+             let root (* the <domain> element *) =
+               match Xml.doc_get_root_element boot_xml_doc with
+               | None -> assert false
+               | Some root -> root in
+             Xml.new_text_child root "clock" ""
+          | [clock_node] -> clock_node
+          | _ ->
+             failwith "multiple <clock> elements found" in
+        Xml.set_prop clock_node "offset" "variable";
+        Xml.set_prop clock_node "basis" "localtime";
+        Xml.set_prop clock_node "adjustment" (string_of_int adjustment)
+    );
+
     (* Remove all devices except for a whitelist. *)
     let xpath = Xml.xpath_eval_expression xpathctx "/domain/devices/*" in
     let nodes = nodes_of_xpathobj boot_xml_doc xpath in
diff --git a/v2v/test-harness/v2v_test_harness.mli b/v2v/test-harness/v2v_test_harness.mli
index f8b3f33f4..739b8192e 100644
--- a/v2v/test-harness/v2v_test_harness.mli
+++ b/v2v/test-harness/v2v_test_harness.mli
@@ -23,6 +23,10 @@
 *)
 
 type test_plan = {
+  guest_clock : float option;
+  (** If not [None], set the guest clock to the specific time.
+      See below for a list of convenient times. *)
+
   post_conversion_test : (Guestfs.guestfs -> string -> Xml.doc -> unit) option;
   (** Arbitrary test that can be run after conversion. *)
 
@@ -58,6 +62,10 @@ and boot_plan =
 | Boot_to_idle                 (** Boot until VM is idle. *)
 | Boot_to_screenshot of string (** Boot until screenshot (subimage) is displayed. *)
 
+val new_year's_day : int -> float option
+(** Set [test_plan.guest_clock = new_year's_day YYYY] to boot the guest with
+    its clock set to midnight on YYYY-01-01. *)
+
 val default_plan : test_plan
 
 val run : test:string -> ?input_disk:string -> ?input_xml:string -> ?test_plan:test_plan -> unit -> unit
diff --git a/v2v/xml-c.c b/v2v/xml-c.c
index d2d895cba..d4f11c551 100644
--- a/v2v/xml-c.c
+++ b/v2v/xml-c.c
@@ -320,6 +320,25 @@ v2v_xml_node_ptr_set_content (value nodev, value contentv)
   CAMLreturn (Val_unit);
 }
 
+value
+v2v_xml_node_ptr_new_text_child (value nodev, value namev, value contentv)
+{
+  CAMLparam3 (nodev, namev, contentv);
+  xmlNodePtr node = (xmlNodePtr) nodev;
+  xmlNodePtr new_node;
+
+  new_node = xmlNewTextChild (node, NULL,
+                              BAD_CAST String_val (namev),
+                              BAD_CAST String_val (contentv));
+  if (new_node == NULL)
+    caml_invalid_argument ("node_ptr_new_text_child: failed to create new node");
+
+  /* See comment in v2v_xml_xpathobj_ptr_get_node_ptr about returning
+   * named xmlNodePtr here.
+   */
+  CAMLreturn ((value) new_node);
+}
+
 value
 v2v_xml_node_ptr_set_prop (value nodev, value namev, value valv)
 {
@@ -345,6 +364,24 @@ v2v_xml_node_ptr_unlink_node (value nodev)
   CAMLreturn (Val_unit);
 }
 
+value
+v2v_xml_doc_get_root_element (value docv)
+{
+  CAMLparam1 (docv);
+  CAMLlocal1 (v);
+  xmlDocPtr doc = Doc_val (docv);
+  xmlNodePtr root;
+
+  root = xmlDocGetRootElement (doc);
+  if (root == NULL)
+    CAMLreturn (Val_int (0));   /* None */
+  else {
+    v = caml_alloc (1, 0);
+    Store_field (v, 0, (value) root);
+    CAMLreturn (v);             /* Some node_ptr */
+  }
+}
+
 value
 v2v_xml_parse_uri (value strv)
 {
diff --git a/v2v/xml.ml b/v2v/xml.ml
index 037bce93d..dbb2b4163 100644
--- a/v2v/xml.ml
+++ b/v2v/xml.ml
@@ -88,12 +88,22 @@ let node_as_string (doc_ptr, node_ptr) = node_ptr_as_string doc_ptr node_ptr
 external node_ptr_set_content : node_ptr -> string -> unit = "v2v_xml_node_ptr_set_content"
 let node_set_content (doc_ptr, node_ptr) = node_ptr_set_content node_ptr
 
+external node_ptr_new_text_child : node_ptr -> string -> string -> node_ptr = "v2v_xml_node_ptr_new_text_child"
+let new_text_child (doc_ptr, node_ptr) name content =
+  doc_ptr, node_ptr_new_text_child node_ptr name content
+
 external node_ptr_set_prop : node_ptr -> string -> string -> unit = "v2v_xml_node_ptr_set_prop"
 let set_prop (doc_ptr, node_ptr) = node_ptr_set_prop node_ptr
 
 external node_ptr_unlink_node : node_ptr -> unit = "v2v_xml_node_ptr_unlink_node"
 let unlink_node (doc_ptr, node_ptr) = node_ptr_unlink_node node_ptr
 
+external _doc_get_root_element : doc_ptr -> node_ptr option = "v2v_xml_doc_get_root_element"
+let doc_get_root_element doc_ptr =
+  match _doc_get_root_element doc_ptr with
+  | None -> None
+  | Some node_ptr -> Some (doc_ptr, node_ptr)
+
 type uri = {
   uri_scheme : string option;
   uri_opaque : string option;
diff --git a/v2v/xml.mli b/v2v/xml.mli
index a3a9c01da..b039d0935 100644
--- a/v2v/xml.mli
+++ b/v2v/xml.mli
@@ -67,6 +67,9 @@ val node_as_string : node -> string
 val node_set_content : node -> string -> unit
 (** xmlNodeSetContent *)
 
+val new_text_child : node -> string -> string -> node
+(** xmlNewTextChild *)
+
 val set_prop : node -> string -> string -> unit
 (** xmlSetProp *)
 
@@ -74,6 +77,9 @@ val unlink_node : node -> unit
 (** xmlUnlinkNode
     {b NB:} This frees the [node], do not use it afterwards. *)
 
+val doc_get_root_element : doc -> node option
+(** xmlDocGetRootElement *)
+
 type uri = {
   uri_scheme : string option;
   uri_opaque : string option;