66 votesAnonymous commented
I found a way to do this. Tap briefly on the PDF document in safari. A not-very-obvious bar appears at the top of the document, with "save to iBooks" on the right and "more" on the left. Tap more, then scroll along the available apps until you see OneDrive and "import with OneDrive".
Another bar will appear at the bottom with "upload to OneDrive". Tap that, select your file location if you wish, then you're done. I know this is an old thread, but I found it whilst trying to find an answer, so I hope this reply helps someone.