diff --git a/Makefile b/Makefile
index 9487b637843..41f21789af8 100644
--- a/Makefile
+++ b/Makefile
@@ -175,3 +175,7 @@ cold: compiler
 
 cold-%:
 	env PATH="`pwd`/bootstrap/ocaml/bin:$$PATH" $(MAKE) $*
+
+.PHONY: run-appveyor-test
+run-appveyor-test:
+	env PATH="`pwd`/bootstrap/ocaml/bin:$$PATH" ./appveyor_test.sh
diff --git a/appveyor.patch b/appveyor.patch
new file mode 100644
index 00000000000..6d459f85e21
--- /dev/null
+++ b/appveyor.patch
@@ -0,0 +1,49 @@
+From 083bae674ad77b6b5b5fafbff25b20473655cb2a Mon Sep 17 00:00:00 2001
+From: David Allsopp <david.allsopp@metastack.com>
+Date: Wed, 27 Dec 2017 10:37:12 +0200
+Subject: [PATCH] Use dra27 jbuilder/ocaml-mccs/flexdll
+
+ - Need unreleased ocaml-mccs 1.1+5 to build mccs on Windows.
+ - Need unreleased jbuilder beta17 to build mccs on MSVC.
+ - Need unreleased flexdll 0.38 to build mccs on mingw.
+---
+ src_ext/Makefile | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+diff --git a/src_ext/Makefile b/src_ext/Makefile
+index 64fdd8af..d1457b5f 100644
+--- a/src_ext/Makefile
++++ b/src_ext/Makefile
+@@ -28,8 +28,8 @@ MD5_cudf = a4c0e652e56e74c7b388a43f9258d119
+ URL_dose3 = https://gforge.inria.fr/frs/download.php/file/36063/dose3-5.0.1.tar.gz
+ MD5_dose3 = e7d4b1840383c6732f29a47c08ba5650
+ 
+-URL_mccs = https://github.com/AltGr/ocaml-mccs/archive/1.1+4.tar.gz
+-MD5_mccs = 1ff2d73ab5c69e1fb58160213fc2d4c9
++URL_mccs = https://github.com/dra27/ocaml-mccs/archive/1.1+4-dra27.tar.gz
++MD5_mccs = 08e80e39a0d960c01955a970d13afb29
+ 
+ URL_opam-file-format = https://github.com/ocaml/opam-file-format/archive/2.0.0-beta5.tar.gz
+ MD5_opam-file-format = 5408798ca3af6e36379dd34b1b618b9c
+@@ -37,14 +37,14 @@ MD5_opam-file-format = 5408798ca3af6e36379dd34b1b618b9c
+ URL_result = https://github.com/janestreet/result/archive/1.2.tar.gz
+ MD5_result = 3d5b66c5526918f0f2ca9d6811ef09c8
+ 
+-URL_jbuilder = https://github.com/janestreet/jbuilder/archive/08050696fb701dafcd1372aadfaa800a50bc01ca.tar.gz
+-MD5_jbuilder = 53b65232ebb5fd319acf90922342615d
++URL_jbuilder = https://github.com/dra27/jbuilder/archive/fix-copy.tar.gz
++MD5_jbuilder = cbf9d2e783feab1f4a61fea35ec96118
+ 
+ URL_ocaml = http://caml.inria.fr/pub/distrib/ocaml-4.04/ocaml-4.04.2.tar.gz
+ MD5_ocaml = 041b8d1a61abc94981a60b6c011e791e
+ 
+-URL_flexdll = http://alain.frisch.fr/flexdll/flexdll-0.35.tar.gz
+-MD5_flexdll = e4449eacf020675e763c21551e841642
++URL_flexdll = https://github.com/dra27/flexdll/archive/linking-c++.tar.gz
++MD5_flexdll = 75bd0efc328ad9f8f2e01414464d217b
+ 
+ ifndef FETCH
+   ifneq ($(shell command -v curl 2>/dev/null),)
+-- 
+2.12.0.windows.1
+
diff --git a/appveyor.yml b/appveyor.yml
index 17333451a21..80109a5eca5 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,25 +1,37 @@
 platform:
-    - x86
+    - x64
+
+image: Visual Studio 2017
 
 environment:
   global:
-    CYG_ROOT: C:/cygwin
+    CYG_ROOT: cygwin64
+    CYG_ARCH: x86_64
+    OCAML_PORT:
     CYG_CACHE: C:/cygwin/var/cache/setup
     CYG_MIRROR: http://mirrors.kernel.org/sourceware/cygwin/
   matrix:
-    -
+    - CYG_ROOT: cygwin
       CYG_ARCH: x86
+    - CYG_ROOT: cygwin64
+      CYG_ARCH: x86_64
+    - OCAML_PORT: msvc
+    - OCAML_PORT: msvc64
+    - OCAML_PORT: mingw
+    - OCAML_PORT: mingw64
+
+cache:
+  - C:\projects\opam\bootstrap
+  - C:\projects\opam\src_ext\archives
 
 init:
-  - 'echo System architecture: %PLATFORM%'
+  - "echo System architecture: %PLATFORM%"
 
 install:
-  - 'appveyor DownloadFile http://cygwin.com/setup-%CYG_ARCH%.exe -FileName setup.exe'
-  - 'setup.exe -gqnNdO -R "%CYG_ROOT%" -s "%CYG_MIRROR%" -l "%CYG_CACHE%" -P make,git,gcc-core,gcc-g++,ocaml,ocaml-camlp4,ocaml-compiler-libs,libncurses-devel,unzip,libmpfr-devel,patch,flexdll,libglpk-devel >NUL'
-  - '%CYG_ROOT%/bin/bash -lc "cygcheck -dc cygwin gcc-core"'
+  - call "%APPVEYOR_BUILD_FOLDER%\appveyor_build.cmd" install
 
 build_script:
-  - '%CYG_ROOT%/bin/bash -lc "cd \"$OLDPWD\" && env DJDIR="workaround" ./configure && make lib-ext && make && make install"'
-  - '%CYG_ROOT%/bin/bash -lc "opam init -y -a"'
-  - '%CYG_ROOT%/bin/bash -lc "opam config env"'
-  - '%CYG_ROOT%/bin/bash -lc "opam install -y -v ocamlfind"'
+  - call "%APPVEYOR_BUILD_FOLDER%\appveyor_build.cmd" build
+
+test_script:
+  - call "%APPVEYOR_BUILD_FOLDER%\appveyor_build.cmd" test
diff --git a/appveyor_build.cmd b/appveyor_build.cmd
new file mode 100644
index 00000000000..9e3c2f8a9a1
--- /dev/null
+++ b/appveyor_build.cmd
@@ -0,0 +1,131 @@
+@rem ***********************************************************************
+@rem *                                                                     *
+@rem *                                 opam                                *
+@rem *                                                                     *
+@rem *                 David Allsopp, OCaml Labs, Cambridge.               *
+@rem *                                                                     *
+@rem *   Copyright 2018 MetaStack Solutions Ltd.                           *
+@rem *                                                                     *
+@rem *   All rights reserved.  This file is distributed under the terms of *
+@rem *   the GNU Lesser General Public License version 2.1, with the       *
+@rem *   special exception on linking described in the file LICENSE.       *
+@rem *                                                                     *
+@rem ***********************************************************************
+
+@rem BE CAREFUL ALTERING THIS FILE TO ENSURE THAT ERRORS PROPAGATE
+@rem IF A COMMAND SHOULD FAIL IT PROBABLY NEEDS TO END WITH
+@rem   || exit /b 1
+@rem BASICALLY, DO THE TESTING IN BASH...
+
+@rem Do not call setlocal!
+@echo off
+
+set CYG_ROOT=C:\%CYG_ROOT%
+
+goto %1
+
+goto :EOF
+
+:CheckPackage
+"%CYG_ROOT%\bin\bash.exe" -lc "cygcheck -dc %1" | findstr %1 > nul
+if %ERRORLEVEL% equ 1 (
+  echo Cygwin package %1 will be installed
+  set CYGWIN_INSTALL_PACKAGES=%CYGWIN_INSTALL_PACKAGES%,%1
+)
+goto :EOF
+
+:UpgradeCygwin
+if "%CYGWIN_INSTALL_PACKAGES%" neq "" "%CYG_ROOT%\setup-%CYG_ARCH%.exe" --quiet-mode --no-shortcuts --no-startmenu --no-desktop --only-site --root "%CYG_ROOT%" --site "%CYG_MIRROR%" --local-package-dir "%CYG_CACHE%" --packages %CYGWIN_INSTALL_PACKAGES:~1% > nul
+for %%P in (%CYGWIN_COMMANDS%) do "%CYG_ROOT%\bin\bash.exe" -lc "%%P --help" > nul || set CYGWIN_UPGRADE_REQUIRED=1
+"%CYG_ROOT%\bin\bash.exe" -lc "cygcheck -dc %CYGWIN_PACKAGES%"
+if %CYGWIN_UPGRADE_REQUIRED% equ 1 (
+  echo Cygwin package upgrade required - please go and drink coffee
+  "%CYG_ROOT%\setup-%CYG_ARCH%.exe" --quiet-mode --no-shortcuts --no-startmenu --no-desktop --only-site --root "%CYG_ROOT%" --site "%CYG_MIRROR%" --local-package-dir "%CYG_CACHE%" --upgrade-also > nul
+  "%CYG_ROOT%\bin\bash.exe" -lc "cygcheck -dc %CYGWIN_PACKAGES%"
+)
+goto :EOF
+
+:install
+cd "%APPVEYOR_BUILD_FOLDER%"
+
+rem CYGWIN_PACKAGES is the list of required Cygwin packages (cygwin is included
+rem in the list just so that the Cygwin version is always displayed on the log).
+rem CYGWIN_COMMANDS is a corresponding command to run with --version to test
+rem whether the package works. This is used to verify whether the installation
+rem needs upgrading.
+set CYGWIN_PACKAGES=cygwin make patch curl diffutils tar unzip
+set CYGWIN_COMMANDS=cygcheck make patch curl diff tar unzip
+
+if "%OCAML_PORT%" equ "mingw" (
+  set CYGWIN_PACKAGES=%CYGWIN_PACKAGES% mingw64-i686-gcc-g++
+  set CYGWIN_COMMANDS=%CYGWIN_COMMANDS% i686-w64-mingw32-g++
+)
+if "%OCAML_PORT%" equ "mingw64" (
+  set CYGWIN_PACKAGES=%CYGWIN_PACKAGES% mingw64-x86_64-gcc-g++
+  set CYGWIN_COMMANDS=%CYGWIN_COMMANDS% x86_64-w64-mingw32-g++
+)
+if "%OCAML_PORT%" equ "" (
+  set CYGWIN_PACKAGES=%CYGWIN_PACKAGES% gcc-g++ flexdll
+  set CYGWIN_COMMANDS=%CYGWIN_COMMANDS% g++ flexlink
+)
+
+set CYGWIN_INSTALL_PACKAGES=
+set CYGWIN_UPGRADE_REQUIRED=0
+
+for %%P in (%CYGWIN_PACKAGES%) do call :CheckPackage %%P
+call :UpgradeCygwin
+
+rem Use dra27 jbuilder/ocaml-mccs/flexdll for native ports
+if "%OCAML_PORT%" neq "" git apply appveyor.patch
+
+set INSTALLED_URL=
+for /f "tokens=3" %%U in ('findstr /C:"URL_ocaml = " src_ext\Makefile') do set OCAML_URL=%%U
+for /f "tokens=3" %%U in ('findstr /C:"URL_flexdll = " src_ext\Makefile') do set FLEXDLL_URL=%%U
+if exist bootstrap\installed-tarball for /f "delims=" %%U in ('type bootstrap\installed-tarball') do set INSTALLED_URL=%%U
+if "%INSTALLED_URL%" neq "%OCAML_URL% %FLEXDLL_URL%" if exist bootstrap\nul (
+  echo Required: %OCAML_URL% %FLEXDLL_URL%
+  echo Compiled: %INSTALLED_URL%
+  echo Re-building bootstrap compiling
+  rd /s/q bootstrap
+  if exist src_ext\archives\nul rd /s/q src_ext\archives
+)
+
+"%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER && make -C src_ext cache-archives" || exit /b 1
+
+if not exist bootstrap\nul (
+  "%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER && make compiler" || exit /b 1
+  if "%CYG_ARCH%%OCAML_PORT%" equ "x86_64" (
+    "%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER && rebase -b 0x7cd20000 bootstrap/ocaml/lib/ocaml/stublibs/dllunix.so" || exit /b 1
+    "%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER && rebase -b 0x7cd20000 bootstrap/ocaml/lib/ocaml/stublibs/dllthreads.so" || exit /b 1
+  )
+  if exist bootstrap\ocaml-*.tar.gz del bootstrap\ocaml-*.tar.gz
+  if "%OCAML_PORT%" neq "" if exist bootstrap\flexdll-*.tar.gz del bootstrap\flexdll-*.tar.gz
+  del bootstrap\ocaml\bin\*.byte.exe
+  if "%OCAML_PORT%" equ "" (
+    del bootstrap\ocaml\lib\ocaml\expunge.exe
+  ) else (
+    del bootstrap\ocaml\lib\expunge.exe
+  )
+  for /f %%D in ('dir /b/ad bootstrap\ocaml-*') do (
+    rd /s/q bootstrap\%%D
+    if "%OCAML_PORT%" equ "" (
+      rem Directory needs to exist, as the Cygwin bootstraps OCAMLLIB refers to it
+      md bootstrap\%%D
+    )
+  )
+)
+
+goto :EOF
+
+:build
+if "%OCAML_PORT%" equ "" (
+  rem make install doesn't yet work for the native Windows builds
+  set POST_COMMAND=^&^& make opam-installer install
+)
+"%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER && ./configure && make lib-ext && make opam %POST_COMMAND%" || exit /b 1
+goto :EOF
+
+:test
+rem Can't yet do an opam init with the native Windows builds
+if "%OCAML_PORT%" equ "" "%CYG_ROOT%\bin\bash.exe" -lc "make -C $APPVEYOR_BUILD_FOLDER run-appveyor-test" || exit /b 1
+goto :EOF
diff --git a/appveyor_test.sh b/appveyor_test.sh
new file mode 100644
index 00000000000..5a6af18e198
--- /dev/null
+++ b/appveyor_test.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+opam init -y -a
+eval $(opam config env)
+opam install -y -v ocamlfind
diff --git a/shell/bootstrap-ocaml.sh b/shell/bootstrap-ocaml.sh
index c98e928cae1..a29dbd9c8a8 100755
--- a/shell/bootstrap-ocaml.sh
+++ b/shell/bootstrap-ocaml.sh
@@ -111,3 +111,4 @@ else
   ${MAKE:-make} world opt.opt
   ${MAKE:-make} install
 fi
+echo "${URL} ${FV_URL}" > ../installed-tarball