equationshorizontal alignmentpdftex

When typing out long equations, I like to split everything up into separate lines and start each one off with an equals sign. How do I hide the first equals sign while keeping the layout exactly the same? I tried wrapping it with \phantom, but that oddly decreases the horizontal offset of the first line:

Here's the source for the above picture:

\documentclass[preview]{standalone}

\usepackage{amsmath}

\begin{document}
\begin{align*}
&\phantom{=} x^2 - 1 \\
&= (x - 1) (x + 1) \\           &= 7
\end{align*}
\end{document}


Moving the ampersands to the other side of the equals signs sort of works, but it makes the equals signs too close to the equations:

Your first attempt almost had it: you just need to write \phantom{{}={}} instead of \phantom{=}.

In the picture below, I've inserted Xs at the start of each line to help ascertain visually that the alignment is working.

\documentclass[preview]{standalone}
\usepackage{amsmath}
\begin{document}
\begin{align*}
&\phantom{{}={}} x^2 - 1 \\
&= (x - 1) (x + 1) \\
&= 7
\end{align*}
\end{document}