3 files changed, 87 insertions, 11 deletions
diff --git a/nt/INSTALL b/nt/INSTALL
index 99a2f3988f9..fff0eb6f8d9 100644
--- a/nt/INSTALL
+++ b/nt/INSTALL
@@ -784,6 +784,15 @@ build will run on Windows 9X and newer systems).
   You need the libiconv-X.Y.Z-N-mingw32-dev.tar.lzma tarball from that
   site.
 
+* Optional support for decompressing text
+
+  Emacs can decompress text if compiled with the zlib library.
+  Prebuilt binaries of zlib DLL (for 32-bit builds of Emacs) are
+  available from the ezwinports site; see above for the URL.
+
+  (This library is also a prerequisite for several image libraries, so
+  you may already have it; look for zlib1.dll or libz-1.dll.)
+
 
 This file is part of GNU Emacs.
 
diff --git a/nt/INSTALL.W64 b/nt/INSTALL.W64
index e109c6f0f23..40670a6a878 100644
--- a/nt/INSTALL.W64
+++ b/nt/INSTALL.W64
@@ -64,13 +64,15 @@ packages (you can copy and paste it into the shell with Shift + Insert):
   mingw-w64-x86_64-libjpeg-turbo \
   mingw-w64-x86_64-librsvg \
   mingw-w64-x86_64-libxml2 \
-  mingw-w64-x86_64-gnutls
+  mingw-w64-x86_64-gnutls \
+  mingw-w64-x86_64-zlib
 
 The packages include the base developer tools (autoconf, automake, grep, make,
 etc.), the compiler toolchain (gcc, gdb, etc.), several image libraries, an
-XML library, and the GnuTLS (transport layer security) library.  Only the
-first three packages are required (base-devel, toolchain, xpm-nox); the rest
-are optional.
+XML library, the GnuTLS (transport layer security) library, and zlib for
+decompressing text.  Only the first three packages are required (base-devel,
+toolchain, xpm-nox); the rest are optional.  You can select only part of the
+libraries if you don't need them all.
 
 You now have a complete build environment for Emacs.
 
diff --git a/nt/README.W32 b/nt/README.W32
index 71a0738969a..a061596da55 100644
--- a/nt/README.W32
+++ b/nt/README.W32
@@ -139,19 +139,21 @@ See the end of the file for license conditions.
   libraries.  These libraries are all available on the following sites:
 
   1. http://sourceforge.net/projects/ezwinports/files/
-     -- leaner, more up-to-date builds, only for 32-bit Emacs
-  2. http://www.gtk.org/download/win32.php
-     http://www.gtk.org/download/win64.php
-     -- the GTK project site; offers much fatter builds, but includes
-        64-bit DLLs (from the 2nd URL)
-  3. GnuWin32 project -- very old builds, not recommended
+     -- up-to-date builds, self-contained archives, only for 32-bit Emacs
+  2. The MSYS2 project -- for 64-bit Emacs:
+     http://msys2.github.io/
+     https://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64/
+  3. GnuWin32 project -- very old 32-bit builds, not recommended
 
   The libraries to download are mentioned below.  Some libraries
   depend on others that need to be downloaded separately from the same
   site; please consult the download instructions on each site for the
   details.  In general, the ezwinports site mentioned above has all
   the dependencies bundled in the same zip archive, so installing from
-  there is the easiest.
+  there is the easiest.  For MSYS2 builds, we recommend that you
+  install and use the 'pacman' utility (available from the MSYS2
+  site), see the instructions below -- it will automatically install
+  all the dependencies.
 
   Emacs will find these libraries if the directory they are installed
   in is on the PATH or in the same directory where you have emacs.exe.
@@ -210,6 +212,69 @@ See the end of the file for license conditions.
   You can get pre-built binaries (including any required DLL and the
   header files) at http://sourceforge.net/projects/ezwinports/files/.
 
+
+* zlib support
+
+  zlib provides support for decompressing text, which is necessary for
+  the zlib-decompress-region primitive.
+
+  Prebuilt binaries of zlib DLL (for 32-bit builds of Emacs) are
+  available from the ezwinports site; see above for the URL.  For the
+  64-bit DLL, see the instructions below for installing from MSYS2
+  site.
+
+  (This library is also a prerequisite for several image libraries, so
+  you may already have it; look for zlib1.dll or libz-1.dll.)
+
+* Installing 64-bit optional libraries from the MSYS2 site
+
+  We recommend that you use the 'pacman' utility to download the
+  libraries you need and all of their dependencies.  If you don't have
+  'pacman' installed, proceed as follows:
+
+  . Install the MSYS2 64-bit (x86_64) installer, named
+    msys2-x86_64-YYYYMMDD.exe (where "YYYYMMDD" is the release date,
+    like 20160205) from http://msys2.github.io/.
+
+  . Run the installer, select the installation directory, make sure
+    "Run MSYS2 now" checkbox is checked, and click "Finish".  A Bash
+    window will open.
+
+  . Type into the Bash window the following command:
+
+    pacman -Sy pacman
+
+    When asked whether to proceed with installation, type Y.
+
+  To install the optional libraries, start the MSYS2 Bash window and
+  type the following command:
+
+    pacman -S PACKAGES
+
+  where PACKAGES is the list of packages you want to install.  The
+  full list is as follows:
+
+   mingw-w64-x86_64-xpm-nox mingw-w64-x86_64-libtiff mingw-w64-x86_64-giflib
+   mingw-w64-x86_64-libpng mingw-w64-x86_64-libjpeg-turbo
+   mingw-w64-x86_64-librsvg mingw-w64-x86_64-libxml2 mingw-w64-x86_64-gnutls
+   mingw-w64-x86_64-zlib
+
+  You can type any subset of this list.  Once again, when asked
+  whether to proceed with installation, answer Y.
+
+  Alternatively, you could install the packages manually from this
+  page:
+
+   https://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64/
+
+  However, the packages there are not self-contained, so you will need
+  to download all their dependencies as well.
+
+  After the installation, if you will be installing Emacs in a
+  directory different from where the DLLs were installed, we recommend
+  to add the directory with DLLs to your PATH, so that Emacs will be
+  able to find those DLLs.
+
 * Uninstalling Emacs
 
   If you should need to uninstall Emacs, simply delete all the files