You can specify the screen density instead of a size like Large or Small
Example:
layout-port-hdpi
layout-port-ldpi
layout-port-mdpi
layout-port-nodpi
layout-land-hdpi
layout-land-ldpi
layout-land-mdpi
layout-land-nodpi
More info in the following link:
http://developer.android.com/intl/fr/guide/topics/resources/resources-i18n.html#AlternateResources
For using Large, Medium, Small this is the way:
res/layout/my_layout.xml // layout for normal screen size
res/layout-small/my_layout.xml // layout for small screen size
res/layout-large/my_layout.xml // layout for large screen size
res/layout-large-land/my_layout.xml // layout for large screen size in landscape mode