R echo code chunk runs off the page using Lyx and Sweave

I am not really sure where in the interactions this is handled, but I 
would like to keep echo-ed R code chunks from running past the right 
margin and off the page.  I started with R and options(width=n), but 
this does not seem to do anything (in the context of a document -- line 
command works just fine).   I have beating my head against different Lyx 
document settings without anything to show.  Anyone point me in the 
right direction?