diff --git a/tools/xenstore/xenstored_control.c b/tools/xenstore/xenstored_control.c
index 3c212cc4d4..1f733e0a04 100644
--- a/tools/xenstore/xenstored_control.c
+++ b/tools/xenstore/xenstored_control.c
@@ -16,6 +16,7 @@ Interactive commands for Xen Store Daemon.
     along with this program; If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <ctype.h>
 #include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -335,6 +336,11 @@ static void lu_get_dump_state(struct lu_dump_state *state)
 static void lu_close_dump_state(struct lu_dump_state *state)
 {
 }
+
+static char *lu_exec(const void *ctx, int argc, char **argv)
+{
+	return "NYI";
+}
 #else
 static const char *lu_binary(const void *ctx, struct connection *conn,
 			     const char *filename)
@@ -434,6 +440,14 @@ static void lu_close_dump_state(struct lu_dump_state *state)
 	unlink(filename);
 	talloc_free(filename);
 }
+
+static char *lu_exec(const void *ctx, int argc, char **argv)
+{
+	argv[0] = lu_status->filename;
+	execvp(argv[0], argv);
+
+	return "Error activating new binary.";
+}
 #endif
 
 static bool lu_check_lu_allowed(void)
@@ -572,7 +586,52 @@ void lu_read_state(void)
 
 static const char *lu_activate_binary(const void *ctx)
 {
-	return "Not yet implemented.";
+	int argc;
+	char **argv;
+	unsigned int i;
+
+	if (lu_status->cmdline) {
+		argc = 4;   /* At least one arg + progname + "-U" + NULL. */
+		for (i = 0; lu_status->cmdline[i]; i++)
+			if (isspace(lu_status->cmdline[i]))
+				argc++;
+		argv = talloc_array(ctx, char *, argc);
+		if (!argv)
+			return "Allocation failure.";
+
+		i = 0;
+		argc = 1;
+		argv[1] = strtok(lu_status->cmdline, " \t");
+		while (argv[argc]) {
+			if (!strcmp(argv[argc], "-U"))
+				i = 1;
+			argc++;
+			argv[argc] = strtok(NULL, " \t");
+		}
+
+		if (!i) {
+			argv[argc++] = "-U";
+			argv[argc] = NULL;
+		}
+	} else {
+		for (i = 0; i < orig_argc; i++)
+			if (!strcmp(orig_argv[i], "-U"))
+				break;
+
+		argc = orig_argc;
+		argv = talloc_array(ctx, char *, orig_argc + 2);
+		if (!argv)
+			return "Allocation failure.";
+
+		memcpy(argv, orig_argv, orig_argc * sizeof(*argv));
+		if (i == orig_argc)
+			argv[argc++] = "-U";
+		argv[argc] = NULL;
+	}
+
+	domain_deinit();
+
+	return lu_exec(ctx, argc, argv);
 }
 
 static bool do_lu_start(struct delayed_request *req)
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index a5c1a56c6c..65ecdd0568 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -73,6 +73,9 @@ static unsigned int delayed_requests;
 
 static int sock = -1;
 
+int orig_argc;
+char **orig_argv;
+
 static bool verbose = false;
 LIST_HEAD(connections);
 int tracefd = -1;
@@ -2077,6 +2080,8 @@ int main(int argc, char *argv[])
 	const char *pidfile = NULL;
 	int timeout;
 
+	orig_argc = argc;
+	orig_argv = argv;
 
 	while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:A:M:T:RVW:U", options,
 				  NULL)) != -1) {
diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
index 6ac5a6fbfa..589699e833 100644
--- a/tools/xenstore/xenstored_core.h
+++ b/tools/xenstore/xenstored_core.h
@@ -222,6 +222,9 @@ void dtrace_io(const struct connection *conn, const struct buffered_data *data,
 void reopen_log(void);
 void close_log(void);
 
+extern int orig_argc;
+extern char **orig_argv;
+
 extern char *tracefile;
 extern int tracefd;
 
diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index cbeb2a309c..3d4d0649a2 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -783,6 +783,12 @@ void domain_init(int evtfd)
 	virq_port = rc;
 }
 
+void domain_deinit(void)
+{
+	if (virq_port)
+		xenevtchn_unbind(xce_handle, virq_port);
+}
+
 void domain_entry_inc(struct connection *conn, struct node *node)
 {
 	struct domain *d;
diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
index 1cc1c03ed8..dc97591713 100644
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -46,6 +46,7 @@ int do_reset_watches(struct connection *conn, struct buffered_data *in);
 
 void domain_init(int evtfd);
 void dom0_init(void);
+void domain_deinit(void);
 
 /* Returns the implicit path of a connection (only domains have this) */
 const char *get_implicit_path(const struct connection *conn);
