diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 63e206e774..70200f37a4 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -83,7 +83,9 @@
 #define LIBXL_INIT_TIMEOUT 10
 #define LIBXL_DESTROY_TIMEOUT 10
 #define LIBXL_HOTPLUG_TIMEOUT 10
-#define LIBXL_DEVICE_MODEL_START_TIMEOUT 10
+/* QEMU may be slow to load and start due to a bug in Linux where the I/O
+ * subsystem sometime produce high latency under load. */
+#define LIBXL_DEVICE_MODEL_START_TIMEOUT 60
 #define LIBXL_QEMU_BODGE_TIMEOUT 2
 #define LIBXL_XENCONSOLE_LIMIT 1048576
 #define LIBXL_XENCONSOLE_PROTOCOL "vt100"