-syn region htmlItalic start="\\\@<!\*\S\@=" end="\S\@<=\\\@<!\*" keepend oneline
-syn region htmlItalic start="\(^\|\s\)\@<=_\|\\\@<!_\([^_]\+\s\)\@=" end="\S\@<=[^\\]_\|[^\\]_\S\@=" keepend oneline
-syn region htmlBold start="\S\@<=\*\*\|\*\*\S\@=" end="\S\@<=\*\*\|\*\*\S\@=" keepend oneline
-syn region htmlBold start="\S\@<=__\|__\S\@=" end="\S\@<=__\|__\S\@=" keepend oneline
-syn region htmlBoldItalic start="\S\@<=\*\*\*\|\*\*\*\S\@=" end="\S\@<=\*\*\*\|\*\*\*\S\@=" keepend oneline
-syn region htmlBoldItalic start="\S\@<=___\|___\S\@=" end="\S\@<=___\|___\S\@=" keepend oneline
+if get(g:, "vim_markdown_emphasis_multiline", 1)
+ syn region htmlItalic start="\%(^\|\s\)\zs\*\ze[^\\\*\t ]" end="[^\\\*\t ]\zs\*\ze\_W" keepend
+ syn region htmlItalic start="\%(^\|\s\)\zs_\ze[^\\_\t ]" end="[^\\_\t ]\zs_\ze\_W" keepend
+ syn region htmlBold start="\*\*\ze\S" end="\S\zs\*\*" keepend
+ syn region htmlBold start="__\ze\S" end="\S\zs__" keepend
+ syn region htmlBoldItalic start="\*\*\*\ze\S" end="\S\zs\*\*\*" keepend
+ syn region htmlBoldItalic start="___\ze\S" end="\S\zs___" keepend
+else
+ " single-line emphasis (emphasis only works with closing token on the same line)
+ syn region htmlItalic start="\%(^\|\s\)\zs\*\ze[^\\\*\t ]\([^\n]*[^\\\*\t ]\)\?\*" end="[^\\\*\t ]\zs\*\ze\_W" keepend
+ syn region htmlItalic start="\%(^\|\s\)\zs_\ze[^\\_\t ]\([^\n]*[^\\_\t ]\)\?_" end="[^\\_\t ]\zs_\ze\_W" keepend
+ syn region htmlBold start="\*\*\ze\S\([^\n]*[^\\\*\t ]\)\?\*\*" end="\S\zs\*\*" keepend
+ syn region htmlBold start="__\ze\S\([^\n]*[^\\_\t ]\)\?__" end="\S\zs__" keepend
+ syn region htmlBold start="\*\*\*\ze\S\([^\n]*[^\\\*\t ]\)\?\*\*\*" end="\S\zs\*\*\*" keepend
+ syn region htmlBold start="___\ze\S\([^\n]*[^\\_\t ]\)\?___" end="\S\zs___" keepend
+endif