diff --git a/bin/generate-exports.py b/bin/generate-exports.py
index 6e98035ee2..cdd0ea4124 100755
--- a/bin/generate-exports.py
+++ b/bin/generate-exports.py
@@ -33,13 +33,52 @@ class Exportable(object):
 
 class Class(Exportable):
 
-    def __init__(self, name, object_literal):
+    def __init__(self, name, object_literal, objects):
         Exportable.__init__(self, name)
         self.object_literal = object_literal
+        self.objects = objects
         self.props = set()
 
     __repr__ = simplerepr
 
+    def nested_options(self):
+        def get_class_by_object_literal_name(name):
+            for k, o in self.objects.iteritems():
+                if isinstance(o, Class) and o.object_literal.name == name:
+                    return o
+            return None
+
+        for option in sorted(self.object_literal.prop_types.keys()):
+            types = self.object_literal.prop_types[option].split('|')
+            base, object_literal = None, None
+            for t in types:
+                if t in self.objects:
+                    o = self.objects[t]
+                    if isinstance(o, (Class, Symbol)):
+                        if base:
+                            raise RuntimeError('Multiple "class" types found for '
+                                'option %s.%s: %s, %s.' %
+                                (self.object_literal.name, option,
+                                 base.name, o.name))
+                        base = o
+                    elif isinstance(o, ObjectLiteral):
+                        if object_literal:
+                            raise RuntimeError('Multiple "literal" types found for '
+                                'option %s.%s: %s, %s.' %
+                                (self.object_literal.name, option,
+                                 object_literal.name, o.name))
+                        object_literal = o
+            if object_literal:
+                if not base:
+                    raise RuntimeError('%s "literal" type found for option %s.%s, '
+                        'but no "class" type.' %
+                        (object_literal.name, self.object_literal.name, option))
+                klass = get_class_by_object_literal_name(object_literal.name)
+                if not klass:
+                    raise RuntimeError('No constructor taking a %s found.' %
+                        object_literal.name)
+                yield option, object_literal, klass, base
+
     def export(self):
         lines = []
         if self.object_literal is None:
@@ -51,10 +90,19 @@ class Class(Exportable):
             lines.append(' * @extends {%s}\n' % (self.name,))
             lines.append(' * @param {%s} options Options.\n' % (self.object_literal.extern_name(),))
             lines.append(' */\n')
-            lines.append('%sExport = function(options) {\n' % (self.name,))
+            lines.append('%s = function(options) {\n' % (self.export_name(),))
             lines.append('  /** @type {%s} */\n' % (self.object_literal.name,))
             lines.append('  var arg;\n');
             lines.append('  if (goog.isDefAndNotNull(options)) {\n')
+            # FIXME: we modify the user's options object
+            lines.append(''.join(
+                         '    if (!(options.%(o)s instanceof %(base)s)) {\n'
+                         '      options.%(o)s = new %(ctor)s(\n'
+                         '          /** @type {%(extern)s} */ (options.%(o)s));\n'
+                         '    }\n' %
+                             {'o': o, 'base': b.name, 'ctor': k.export_name(),
+                              'extern': ol.extern_name()} \
+                                     for o, ol, k, b in self.nested_options()))
             lines.append('    arg = {')
             lines.extend(','.join('\n      %s: options.%s' % (key, key) for key in sorted(self.object_literal.prop_types.keys())))
             lines.append('\n    };\n')
@@ -66,10 +114,13 @@ class Class(Exportable):
             lines.append('goog.inherits(%sExport, %s);\n' % (self.name, self.name))
             lines.append('goog.exportSymbol(\n')
             lines.append('    \'%s\',\n' % (self.name,))
-            lines.append('    %sExport);\n' % (self.name,))
+            lines.append('    %s);\n' % (self.export_name(),))
         lines.extend('goog.exportProperty(\n    %s,\n    \'%s\',\n    %s.%s);\n' % (self.name, prop, self.name, prop) for prop in sorted(self.props))
         return ''.join(lines)
 
+    def export_name(self):
+        return '%sExport' % self.name
+
 
 class ObjectLiteral(Exportable):
 
@@ -161,7 +212,7 @@ def main(argv):
                 object_literal = objects[object_literal_name]
                 if not isinstance(object_literal, ObjectLiteral):
                     raise RuntimeError(line)  # Undefined object literal
-                klass = Class(name, object_literal)
+                klass = Class(name, object_literal, objects)
                 objects[name] = klass
                 continue
             m = re.match(r'@exportObjectLiteral\s+(?P<name>\S+)\Z', line)