diff --git a/dom0/qvm-core/qubes.py b/dom0/qvm-core/qubes.py
index e5c01eb6..45d41393 100755
--- a/dom0/qvm-core/qubes.py
+++ b/dom0/qvm-core/qubes.py
@@ -870,9 +870,15 @@ class QubesVm(object):
 
         return args
 
+    @property
+    def uses_custom_config(self):
+        return self.conf_file != self.absolute_path(self.name + ".conf", None)
+
     def create_config_file(self, file_path = None, source_template = None, prepare_dvm = False):
         if file_path is None:
             file_path = self.conf_file
+            if self.uses_custom_config:
+                return
         if source_template is None:
             source_template = self.template
 
diff --git a/dom0/qvm-tools/qvm-start b/dom0/qvm-tools/qvm-start
index 1211d265..23027c03 100755
--- a/dom0/qvm-tools/qvm-start
+++ b/dom0/qvm-tools/qvm-start
@@ -39,6 +39,8 @@ def main():
                       help="Attach debugging console to the newly started VM")
     parser.add_option ("--dvm", action="store_true", dest="preparing_dvm", default=False,
                       help="Do actions necessary when preparing DVM image")
+    parser.add_option ("--custom-config", action="store", dest="custom_config", default=None,
+                      help="Use custom Xen config instead of Qubes-generated one")
 
     (options, args) = parser.parse_args ()
     if (len (args) != 1):
@@ -55,6 +57,9 @@ def main():
         print >> sys.stderr, "A VM with the name '{0}' does not exist in the system.".format(vmname)
         exit(1)
 
+    if options.custom_config:
+        vm.conf_file = options.custom_config
+
     try:
         vm.verify_files()
         xid = vm.start(debug_console=options.debug_console, verbose=options.verbose, preparing_dvm=options.preparing_dvm)