Here is a function to capitalize a last name, accounting for hyphens, apostrophes, "Mc" and "Mac":

<?php
function CapitalizeLastName($name) {
    $name = strtolower($name);
    $name = join("'", array_map('ucwords', explode("'", $name)));
    $name = join("-", array_map('ucwords', explode("-", $name)));
    $name = join("Mac", array_map('ucwords', explode("Mac", $name)));
    $name = join("Mc", array_map('ucwords', explode("Mc", $name)));
    return $name;
}
?>

I speed tested it against functions that used preg_replace() with an "e" modifier, preg_replace_callback(), and a character-by-character parsing.  Unexpectedly, this function using join(), array_map() and explode() was fastest.