arxiv.tex
\documentclass[a4paper]{article}
 \pdfoutput=1
%\usepackage{hyperref}
%\hypersetup{
%  pdfinfo={
%    Title={Your Title Here},
%    Author={Your Name Here},
%    Subject={If you want to put something here, do so},
%    Keywords={Add some keywords if you feel so inclined}
%  }
%}
\usepackage{pdfpages}

\begin{document}
\includepdf[pages=1-last]{File_1.pdf}
\includepdf[pages=1-last]{File_2.pdf}
\end{document}