--- a/contrib/win32/mercurial.iss	Sat Sep 11 09:48:10 2010 +0200
+++ b/contrib/win32/mercurial.iss	Sat Sep 11 18:48:03 2010 +0200
@@ -16,10 +16,22 @@
 #pragma message "Detected Version: " + VERSION
 #endif
 
+#ifndef ARCH
+#define ARCH = "x86"
+#endif
+
 [Setup]
 AppCopyright=Copyright 2005-2010 Matt Mackall and others
 AppName=Mercurial
+#if ARCH == "x64"
+AppVerName=Mercurial {#VERSION} (64-bit)
+OutputBaseFilename=Mercurial-{#VERSION}-x64
+ArchitecturesAllowed=x64
+ArchitecturesInstallIn64BitMode=x64
+#else
 AppVerName=Mercurial {#VERSION}
+OutputBaseFilename=Mercurial-{#VERSION}
+#endif
 InfoAfterFile=contrib/win32/postinstall.txt
 LicenseFile=COPYING
 ShowLanguageDialog=yes
@@ -29,7 +41,6 @@
 AppUpdatesURL=http://mercurial.selenic.com/
 AppID={{4B95A5F1-EF59-4B08-BED8-C891C46121B3}
 AppContact=mercurial@selenic.com
-OutputBaseFilename=Mercurial-{#VERSION}
 DefaultDirName={pf}\Mercurial
 SourceDir=..\..
 VersionInfoDescription=Mercurial distributed SCM (version {#VERSION})
@@ -61,11 +72,16 @@
 Source: contrib\win32\mercurial.ini; DestDir: {app}; DestName: Mercurial.ini; Check: CheckFile; AfterInstall: ConcatenateFiles;
 Source: contrib\win32\postinstall.txt; DestDir: {app}; DestName: ReleaseNotes.txt
 Source: dist\hg.exe; DestDir: {app}; AfterInstall: Touch('{app}\hg.exe.local')
+#if ARCH == "x64"
+Source: dist\*.dll; Destdir: {app}
+Source: dist\*.pyd; Destdir: {app}
+#else
 Source: dist\python*.dll; Destdir: {app}; Flags: skipifsourcedoesntexist
-Source: dist\library.zip; DestDir: {app}
 Source: dist\msvc*.dll; DestDir: {app}; Flags: skipifsourcedoesntexist
+Source: dist\w9xpopen.exe; DestDir: {app}
+#endif
 Source: dist\Microsoft.VC*.CRT.manifest; DestDir: {app}; Flags: skipifsourcedoesntexist
-Source: dist\w9xpopen.exe; DestDir: {app}
+Source: dist\library.zip; DestDir: {app}
 Source: dist\add_path.exe; DestDir: {app}
 Source: doc\*.html; DestDir: {app}\Docs
 Source: doc\style.css; DestDir: {app}\Docs

--- a/contrib/win32/win32-build.txt	Sat Sep 11 09:48:10 2010 +0200
+++ b/contrib/win32/win32-build.txt	Sat Sep 11 18:48:03 2010 +0200
@@ -1,7 +1,8 @@
 The standalone Windows installer for Mercurial is built in a somewhat
 jury-rigged fashion.
 
-It has the following prerequisites, at least as I build it:
+It has the following prerequisites. Ensure to take the packages
+matching the mercurial version you want to build (32-bit or 64-bit).
 
   Python 2.6 for Windows
       http://www.python.org/download/releases/
@@ -19,7 +20,10 @@
       http://starship.python.net/crew/mhammond/win32/
 
   Visual C++ 2008 SP1 redistributable package (needed for >= Python 2.6 or if you compile with MSVC)
+    for 32-bit:
       http://www.microsoft.com/downloads/details.aspx?FamilyID=A5C84275-3B97-4AB7-A40D-3802B2AF5FC2
+    for 64-bit:
+      http://www.microsoft.com/downloads/details.aspx?familyid=BA9257CA-337F-4B40-8C14-157CFDFFEE4E
       
   The py2exe distutils extension
       http://sourceforge.net/projects/py2exe/
@@ -62,7 +66,12 @@
 you can skip the first build step.
 
 Building instructions with MSVC 2008 SP1 Express Edition:
-  python setup.py py2exe -b 2
+  for 32-bit:
+    "C:\Program Files\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" x86
+    python setup.py py2exe -b 2
+  for 64-bit:
+    "C:\Program Files\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" x86_amd64
+    python setup.py py2exe -b 3
 
 Copy add_path.exe into the dist directory that just got created.
 
@@ -74,11 +83,13 @@
 install the Visual C++ 2008 SP1 redistributable package. Then in your
 windows\winsxs folder, locate the folder containing the dlls version 9.0.30729.
 For x86, it should be named like x86_Microsoft.VC90.CRT_(...)_9.0.30729(...).
+For x64, it should be named like amd64_Microsoft.VC90.CRT_(...)_9.0.30729(...).
 Copy the files named msvcm90.dll, msvcp90.dll and msvcr90.dll into the dist
 directory.
 Then in the windows\winsxs\manifests folder, locate the corresponding manifest
-file (x86_Microsoft.VC90.CRT_(...)_9.0.30729(...).manifest for x86), copy it in
-the dist directory and rename it to Microsoft.VC90.CRT.manifest.
+file (x86_Microsoft.VC90.CRT_(...)_9.0.30729(...).manifest for x86,
+amd64_Microsoft.VC90.CRT_(...)_9.0.30729(...).manifest for x64), copy it in the
+dist directory and rename it to Microsoft.VC90.CRT.manifest.
 
 Before building the installer, you have to build Mercurial HTML documentation 
 (or fix mercurial.iss to not reference the doc directory):
@@ -101,6 +112,10 @@
 If the /dVERSION=foo parameter is not given in the command line, the
 installer will retrieve the version information from the __version__.py file.
 
+If you want to build an installer for a 64-bit mercurial, add /dARCH=x64 to
+your command line:
+  iscc contrib\win32\mercurial.iss /dARCH=x64
+
 To automate the steps above you may want to create a batchfile based on the
 following (MinGW build chain):