I'm not sure what you mean by quick, but:

use strict;
use warnings;

my @elems = ("x", "y", "z");
my @tobepopulated = ("foo", "foo", "foo", "foo", "foo", "foo", "foo", 
+"foo", "foo", "foo");

die "Too few elements to populate" unless @tobepopulated ;

my $inc = @elems / @tobepopulated;
my $elIndex = $inc;

for my $to (@tobepopulated) {
    $to .= "-$elems[$elIndex]";
    $elIndex += $inc;
}

print "@tobepopulated";
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Prints:

foo-x foo-x foo-x foo-y foo-y foo-y foo-z foo-z foo-z foo-z
[download]

and may be something like what you are after.