How to redirect to l() function link after login?
You can add a additional destination parameter to the function.

&lt;?php
print l(t('Title'), 'url', array('query' =&gt; array('destination' =&gt; 'destination_url')))
?&gt; 


This will create : 

&lt;a href="url?destination=destination_url"&gt;Title&lt;/a&gt;


Hope it helps.