+@unnumberedsubsubsec Compiling outside the source tree
+
+It is possible to compile LilyPond in a build tree different from the
+source tree, with @code{--srcdir} option of @command{configure}:
+
+@example
+mkdir lily-build && cd lily-build
+@var{sourcedir}/configure --srcdir=@var{sourcedir}
+
+@end example
+
+
+@unnumberedsubsubsec Useful @command{make} variables
+
+If a less verbose build output if desired, the variable
+@code{QUIET_BUILD} may be set to @code{1} on @command{make} command
+line, or in @file{local.make} at top of the build tree.
+
+
+@node Building documentation
+@subsection Building documentation
+
+This requires a successful compile of LilyPond, or using an external
+LilyPond binary.
+
+@menu
+* Commands for building documentation:: Compiling and installing the documentation.
+* Building documentation without compiling LilyPond:: Using a LilyPond binary already installed.
+@end menu
+
+@node Commands for building documentation
+@unnumberedsubsubsec Commands for building documentation
+
+The documentation is built by issuing
+
+@example
+make web
+@end example
+
+After compilation, the HTML documentation tree is available in
+@file{out-www/offline-root/}, and can be browsed locally.
+
+The HTML and PDF files can be installed into the standard documentation
+path by issuing
+
+@example
+make web-install
+@end example
+
+@noindent
+This also installs Info documentation with images if the installation
+prefix is properly set; otherwise, instructions for manual installation
+of Info documentation are printed on standard output.
+
+It is also possible to build a documentation tree in
+@file{out-www/online-root/}, with special processing, so it can be used
+on a website with content negotiation for automatic language selection;
+this can be achieved by issuing
+
+@example
+make WEB_TARGETS=online web
+@end example
+
+@noindent
+and both @q{offline} and @q{online} targets can be generated by issuing
+
+@example
+make WEB_TARGETS="offline online" web
+@end example
+
+Several targets are available to clean the documentation build and
+help with maintaining documentation; an overview of these targets is
+available with
+
+@example
+make help
+@end example
+
+@noindent
+from every directory in the build tree. Most targets for
+documentation maintenance are available from @file{Documentation/};
+for more information, see @file{Documentation/user/README.txt} and
+@file{Documentation/TRANSLATION}.
+
+The makefile variable @code{QUIET_BUILD} may be set to @code{1} for a
+less verbose build output, just like for building the programs.
+
+@knownissues
+
+The most time consuming task for building the documentation is running
+LilyPond to build images of music, and there cannot be several
+simultaneously running @command{lilypond-book} instances, so @code{-j}
+@command{make} option does not significantly speed up the build process.
+To help speed it up, the makefile variable @var{CPU_COUNT} may be set
+in @file{local.make} or on the command line to the number of
+@code{.ly} files that LilyPond should process simultaneously, e.g. on
+a bi-processor or dual core machine
+
+@example
+make -j3 CPU_COUNT=3 web
+@end example
+
+@noindent
+The recommended value of @var{CPU_COUNT} is one plus the number of
+cores or processors, but it is advisable to set it to a smaller value
+if your system has not enough RAM to run that many simultaneous
+LilyPond instances.
+
+If source files have changed since last documentation build, output
+files that need to be rebuilt are normally rebuilt, even if you do not
+run @code{make web-clean} first. However, building dependencies in the
+documentation are so complex that rebuilding of some targets may not
+be triggered as they should be; a workaround is to force rebuilding
+by touching appropriate files, e.g.
+
+@example
+touch Documentation/user/*.itely
+touch input/lsr/*.ly
+@end example
+
+