diff --git a/hphp/hack/.gitignore b/hphp/hack/.gitignore
index 38c489bb7fdb42..0977c349b9c537 100644
--- a/hphp/hack/.gitignore
+++ b/hphp/hack/.gitignore
@@ -12,3 +12,5 @@ src/parsing/parser.mli
 *.so
 *.annot
 *.opt
+_obuild/
+.ocp/
\ No newline at end of file
diff --git a/hphp/hack/00_config.ocp b/hphp/hack/00_config.ocp
new file mode 100644
index 00000000000000..1409b346b542cd
--- /dev/null
+++ b/hphp/hack/00_config.ocp
@@ -0,0 +1,3 @@
+
+have_lz4 = false
+debug = false
diff --git a/hphp/hack/README.ocpbuild b/hphp/hack/README.ocpbuild
new file mode 100644
index 00000000000000..f1fa0611e0dd6c
--- /dev/null
+++ b/hphp/hack/README.ocpbuild
@@ -0,0 +1,45 @@
+This document describes an alternative build-system for Hack. This is
+currently the only build system available on Windows. Meanwhile, this
+document focuses on using this alternative build system on Linux and
+OS X; for Windows, see `README.win32`.
+
+### ocp-build, a build system for OCaml applications
+
+ocp-build is a build system for OCaml applications, based on simple
+descriptions of packages. ocp-build combines the descriptions of
+packages in different directories, and optimize the parallel incremental
+compilation of files depending on the number of cores and the 
+automatically-infered dependencies between source files.
+
+For more details, you can take a look at
+
+   http://www.typerex.org/ocp-build.html
+
+### Download and install `ocp-build` by using OPAM
+
+OPAM is a source-based package manager for OCaml. It supports multiple
+simultaneous compiler installations, flexible package constraints, and
+a Git-friendly development workflow.
+
+To install OPAM, please check http://opam.ocaml.org/doc/Install.html
+
+Once OPAM is installed correctly with an OCaml compiler, you can setup
+your configuration and installl `ocp-build`:
+
+    $ opam init
+    $ eval $(opam config env)
+    $ opam install ocp-build
+
+Note that you will always need to use `eval $(opam config env)` when restarting
+a shell in a terminal, to get your PATH properly configured.
+
+### Compiling Hack with ocp-build
+
+For Windows, see `README.win32.` Otherwise in `hack/src`, run:
+
+  $ make fast
+
+Optionally, you may run:
+
+  $ make test-ocp
+  
\ No newline at end of file
diff --git a/hphp/hack/README.win32 b/hphp/hack/README.win32
new file mode 100644
index 00000000000000..30120ee462236e
--- /dev/null
+++ b/hphp/hack/README.win32
@@ -0,0 +1,67 @@
+We are currently porting Hack and Flow to Windows 64 bits. This
+document describes the build system, if you want to test
+the prototype. Be aware that this work will take some time
+and most tests are currently known to fail.
+
+### Dependency: OCPWin
+
+OCPWin is a binary OCaml distribution for Windows. It is
+self-contained and runs natively on Windows, which means you can
+generate OCaml applications with it without installing Cygwin or
+Windows SDK.
+
+To download and install OCPWin, go to http://www.typerex.org/ocpwin.html,
+and choose the "full" version. OCPWin installer is known to have problems
+with PATHs exceeding 1024 characters. Be careful to save your PATH before
+the installation to be able to restore it in case of problem, until the
+problem is fixed.
+
+### Configuration and Compilation
+
+In the Hack root directory, edit the file  `00_config.ocp`
+and adjust the two following variables:
+
+    has_lz4 = false (* true if lz4 is installed on your machine *)
+    debug = false   (* true if you want to activate the debug mode *)
+
+NOTE: lz4 is not required to build Hack. If you want to use it, and lz4 is not
+      installed in the default path, you have to set the
+      `ccopt` variable correctly in the `00_config.ocp` file. For instance:
+
+    ccopt = [ "-I/PATH/TO/LZ4/DIRECTORY" ]
+
+Then, execute the `make.bat` script:
+
+    ./make
+
+This will call `ocp-build` and copy the generated files into the bin/
+sub-directory.
+
+If you want to clean your project, you may use:
+
+    ./make clean
+
+Optionally, to run the test-suite adjust the path to the `python.exe`
+in `make.bat`, and run:
+
+    ./make test
+
+### Installing
+
+Coming soon
+
+### FAQ
+
+Q: While installing OCPWin, I got this message error:
+
+    This version of C:\xxxx is not compatible with the version of
+    Windows that you're running. Check your computer's system information
+    and then contact the software publisher.
+
+   What should I do ?
+
+A: You probably installed the wrong version of OCPWin, check that you
+   got the 32 or 64 bits version according to your system. Note that Hack
+   and Flow currently only work on 64 bits systems.
+   
+   
\ No newline at end of file
diff --git a/hphp/hack/build.ocp b/hphp/hack/build.ocp
new file mode 100644
index 00000000000000..b591476c53140f
--- /dev/null
+++ b/hphp/hack/build.ocp
@@ -0,0 +1,14 @@
+(**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+begin library "ROOTPROJECT"
+  files = []
+end
+
diff --git a/hphp/hack/make.bat b/hphp/hack/make.bat
new file mode 100644
index 00000000000000..8c24a6c8754820
--- /dev/null
+++ b/hphp/hack/make.bat
@@ -0,0 +1,62 @@
+
+@echo off
+
+if "%1" == "" goto build
+if "%1" == "build" goto build
+if "%1" == "all" goto build
+if "%1" == "test" goto test
+if "%1" == "init" goto init
+if "%1" == "clean" goto clean
+REM Invalid argument
+echo Invalid argument, please check README.win32
+goto end
+
+REM initialize ocp-build and create _obuild directory
+:init
+if not exist "_obuild/" ocp-build init
+goto end
+
+REM 1/ check if ocp-build init has already be done
+REM 2/ generate get_build_id.gen.c
+REM 3/ start build hack with ocp-build
+:build
+if not exist "_obuild/" ocp-build init
+ocaml.exe unix.cma ./src/scripts/gen_build_id.ml ./src/utils/get_build_id.gen.c
+ocp-build
+md bin 2>NUL
+copy _obuild\hh_server\hh_server.asm.exe bin\hh_server.exe
+copy _obuild\hh_client\hh_client.asm.exe bin\hh_client.exe
+copy _obuild\hh_single_type_check\hh_single_type_check.asm.exe bin\hh_single_type_check.exe
+copy _obuild\hh_format\hh_format.asm.exe bin\hh_format.exe
+copy _obuild\h2tp\h2tp.asm.exe bin\h2tp.exe
+
+goto end
+
+REM clean _obuild directory and executables in bin/
+:clean
+ocp-build clean
+del bin\hh_server.exe 2>NUL
+del bin\hh_client.exe 2>NUL
+del bin\hh_single_type_check.exe 2>NUL
+del bin\hh_format.exe 2>NUL
+del bin\h2tp.exe 2>NUL
+goto end
+
+REM execute the Hack testsuite
+:test
+@echo on
+
+set "python3=python.exe"
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/autocomplete
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/color
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/coverage
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/dumpsymbolinfo
+"%python3%" test/verify.py --program bin/hh_format.exe test/format
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/suggest
+"%python3%" test/verify.py --program bin/hh_single_type_check.exe test/typecheck
+"%python3%" test/verify.py --program bin/hh_format.exe test/typecheck ^
+		--disabled-extension .no_format ^
+		--out-extension .format_out ^
+		--expect-extension '' ^
+		--flags --root .
+:end
diff --git a/hphp/hack/src/Makefile b/hphp/hack/src/Makefile
index 19b5febe61bdc1..1ceca1d76f7f31 100644
--- a/hphp/hack/src/Makefile
+++ b/hphp/hack/src/Makefile
@@ -103,6 +103,7 @@ LINKER_FLAGS=$(NATIVE_OBJECT_FILES) $(NATIVE_LIB_OPTS) $(EXTRA_LIB_OPTS) \
 rwildcard=$(wildcard $1$2) $(foreach d,$(wildcard $1*),$(call rwildcard,$d/,$2))
 
 all: build-hhi-archive build-hack copy-hack-files
+all-ocp: build-hhi-archive build-hack-with-ocp copy-hack-files-ocp
 
 clean:
 	ocamlbuild -clean
@@ -111,6 +112,10 @@ clean:
 
 build-hack: $(TARGETS) build-hhi-archive
 
+build-hack-with-ocp: build-hhi-archive build-hack-stubs-with-ocp
+	[ -d ${ROOT}/../_obuild ] || ( cd ${ROOT}/.. && ocp-build init )
+	ocp-build build
+
 # All targets are built in one time, so no parallelization is necessary
 .NOTPARALLEL: $(TARGETS)
 # As there is no efficient way to calculate the dependencies of
@@ -131,9 +136,15 @@ $(TARGETS): $(ALL_SRC_FILES)
 build-hack-native-deps: build-hack-stubs
 	ocamlbuild -cflags "-g $(EXTRA_INCLUDE_OPTS) $(EXTRA_CC_OPTS)" $(NATIVE_OBJECT_FILES)
 
+# If you modify this rule, do not forget to edit the file
+# `$(ROOT)/scripts/gen_build_id.ml` used on Windows.
 build-hack-stubs:
 	REV="const char* const BuildInfo_kRevision = \"$$(git rev-parse HEAD)\";"; \
-	if [ "$$REV" != "$$(cat utils/get_build_id.gen.c)" ]; then echo "$$REV" > utils/get_build_id.gen.c; fi
+	if [ "$$REV" != "$$(cat scripts/get_build_id.gen.c)" ]; then echo "$$REV" > utils/get_build_id.gen.c; fi
+
+build-hack-stubs-with-ocp:
+	ocaml unix.cma $(ROOT)/scripts/gen_build_id.ml \
+                       $(ROOT)/utils/get_build_id.gen.c
 
 build-hhi-archive:
 	mkdir -p ../bin
@@ -152,7 +163,27 @@ endif
 	cp _build/hh_format.native ../bin/hh_format
 	cp _build/h2tp/h2tp.native ../bin/h2tp
 
+copy-hack-files-ocp: build-hack-with-ocp
+	mkdir -p ../bin
+ifeq ($(OS), Linux)
+	objcopy --add-section hhi=../bin/hhi.tar.gz ../_obuild/hh_server/hh_server.asm ../bin/hh_server
+else
+	cp ../_obuild/hh_server/hh_server.asm ../bin/hh_server
+endif
+	cp ../_obuild/hh_client/hh_client.asm ../bin/hh_client
+	cp ../_obuild/hh_single_type_check/hh_single_type_check.asm ../bin/hh_single_type_check
+	cp ../_obuild/hh_format/hh_format.asm ../bin/hh_format
+	cp ../_obuild/h2tp/h2tp.asm ../bin/h2tp
+
+
+.PHONY: test test-ocp do-test
 test: build-hack copy-hack-files
+	${MAKE} do-test
+
+test-ocp: build-hack-with-ocp copy-hack-files-ocp
+	${MAKE} do-test
+
+do-test:
 	python3 ../test/verify.py --program ../bin/hh_single_type_check ../test/autocomplete
 	python3 ../test/verify.py --program ../bin/hh_single_type_check ../test/color
 	python3 ../test/verify.py --program ../bin/hh_single_type_check ../test/coverage
diff --git a/hphp/hack/src/build.ocp b/hphp/hack/src/build.ocp
new file mode 100644
index 00000000000000..8842b9780c71b3
--- /dev/null
+++ b/hphp/hack/src/build.ocp
@@ -0,0 +1,458 @@
+(**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+comp = [ "-thread" ]
+link = [ "-thread" ]
+
+if debug then {
+  comp += [ "-g" ]
+  link += [ "-g" ]
+}
+
+if os_type = "linux" then {
+  cclib = [ "-lelf" ]
+}
+
+if have_lz4 then {
+  cclib += [ "-llz4" ]
+} else {
+  ccopt += [ "-DNO_LZ4" ]
+}
+
+requires = [ "unix" "str" "threads" ]
+
+begin library "hh-third-party"
+
+  files = [
+    "third-party/core/caml.ml"
+    "third-party/core/commutative_group.ml"
+    "third-party/core/container.ml"
+    "third-party/core/core_printf.ml"
+    "third-party/core/monad.ml"
+    "third-party/core/polymorphic_compare.ml"
+    "third-party/core/poly.ml"
+    "third-party/core/core_list.ml"
+    "third-party/core/option.ml"
+    "third-party/core/result.ml"
+    "third-party/avl/monoidAvl.ml"
+  ]
+end
+
+begin library "hh-fsnotify-linux"
+  if not (system = "linux" && os_type = "Unix") then enabled = false
+  cclib = [ "-lelf" ]
+  files = [
+    "third-party/inotify/inotify_stubs.c"
+    "third-party/inotify/inotify.ml"
+    "fsnotify_linux/fsnotify.ml"
+  ]
+  requires = [ "hh-utils-core" ]
+end
+
+begin library "hh-fsnotify-darwin"
+  if not (system = "macosx" && os_type = "Unix") then enabled = false
+  cclib = [
+    "-sectcreate" "-__text" "hhi" "%{ROOTPROJECT_FULL_SRC_DIR}%/bin/hhi.tar.gz"
+    "-framework" "CoreServices"
+    "-framework" "CoreFoundation"
+  ]
+  files = [
+    "fsevents/fsevents_stubs.c"
+    "fsevents/fsevents.ml"
+    "fsnotify_darwin/fsnotify.ml"
+  ]
+  requires += [ "ROOTPROJECT" ]
+end
+
+begin library "hh-fsnotify-win"
+  if not (os_type = "Win32") then enabled = false
+  requires += [ "ROOTPROJECT" ]
+  files = [ "fsnotify_win/fsnotify.ml" ]
+end
+
+begin library "hh-fsnotify"
+  if os_type = "Win32" then {
+    requires = [ "hh-fsnotify-win" ]
+  } else if system = "linux" then {
+    requires = [ "hh-fsnotify-linux" ]
+  } else {
+    requires = [ "hh-fsnotify-darwin" ]
+  }
+end
+
+begin library "hh-utils-core"
+  requires = [ "hh-third-party" ]
+  files = [ "utils/core.ml" ]
+end
+
+begin library "hh-utils-common"
+  requires += [ "hh-third-party" "hh-utils-core" "hh-fsnotify" ]
+  files = [
+    "heap/hh_shared.c"
+
+    "utils/get_build_id.gen.c"
+    "utils/get_build_id.c"
+    "utils/nproc.c"
+    "utils/realpath.c"
+    "utils/hh_json.ml"
+    "utils/ident.ml"
+    "utils/utils.ml"
+    "utils/sys_utils.ml"
+    "utils/path.ml"
+    "utils/relative_path.ml"
+    "utils/pos.ml"
+    "utils/errors.ml"
+    "utils/lint.ml"
+    "utils/config_file.ml"
+  ]
+end
+
+begin library "hh-utils"
+  requires += [ "hh-utils-common" ]
+  files = [
+    "utils/tmp.ml"
+    "utils/lock.ml"
+    "utils/pidLog.ml"
+    "utils/fork.ml"
+    "utils/daemon.ml"
+    "utils/build_id.ml"
+    "utils/wwwroot.ml"
+    "utils/tty.ml"
+    "utils/printSignal.ml"
+    "utils/trie.ml"
+    "utils/find.ml"
+    "utils/hh_logger.ml"
+    "utils/exit_status.ml"
+  ]
+end
+
+begin library "hh-deps"
+  requires += [ "hh-third-party" "hh-utils" ]
+  files = [
+    "deps/fileInfo.ml"
+    "deps/typing_deps.ml"
+  ]
+end
+
+begin library "hh-stubs"
+  requires += [ "hh-utils" ]
+  files = [
+    "stubs/eventLogger.ml"
+    "stubs/hackEventLogger.ml"
+    "stubs/filesToIgnore.ml"
+    "stubs/linting_service.ml"
+    "stubs/prologMain.ml"
+    "stubs/buildMain.ml"
+    "stubs/prolog.ml"
+  ]
+end
+
+begin library "hh-heap"
+  requires += [ "hh-third-party"  "hh-utils" "hh-stubs" ]
+
+  files = [
+    "heap/prefix.ml"
+    "heap/value.ml"
+    "heap/sharedMem.ml"
+    "heap/globalStorage.ml"
+  ]
+end
+
+begin library "hh-globals"
+  requires += [ "hh-third-party" "hh-utils" ]
+
+  files = [
+    "globals/autocomplete.ml"
+    "globals/ide.ml"
+    "globals/globalConfig.ml"
+  ]
+end
+
+begin library "hh-procs"
+  requires += [ "hh-third-party" "hh-utils" "hh-heap" "hh-globals" ]
+
+  files = [
+    "procs/worker.ml"
+    "procs/multiWorker.ml"
+    "procs/bucket.ml"
+  ]
+end
+
+begin library "hh-parsing"
+  requires += [ "hh-third-party" "hh-utils" "hh-deps" "hh-heap"
+                "hh-globals"  "hh-procs" ]
+  files = [
+    "parsing/namespace_env.ml"
+    "parsing/ast.ml"
+    "parsing/lexer_hack.mll"
+    "parsing/namespaces.ml"
+    "parsing/parser_heap.ml"
+    "parsing/parser_hack.ml"
+    "parsing/parsing_hooks.ml"
+    "parsing/ast_utils.ml"
+    "parsing/parsing_service.ml"
+  ]
+end
+
+begin library "hh-typing-base"
+  requires += [ "hh-utils" "hh-parsing" ]
+  files = [
+    "naming/naming_special_names.ml"
+    "typing/typing_reason.ml"
+    "typing/typing_defs.ml"
+    "typing/typing_heap.ml"
+    "naming/naming_hooks.ml"
+    "naming/naming_ast_helpers.ml"
+    "naming/typecheckerOptions.ml"
+    "naming/nast.ml"
+    "naming/naming.ml"
+  ]
+end
+
+begin library "hh-dfind"
+  requires += [ "hh-third-party" "hh-fsnotify" "hh-utils" ]
+  files = [
+    "dfind/dfindEnv.ml"
+    "dfind/dfindMaybe.ml"
+    "dfind/dfindAddFile.ml"
+    "dfind/dfindServer.ml"
+    "dfind/dfindLib.ml"
+  ]
+end
+
+begin library "hh-naming"
+  requires += [ "hh-typing-base" ]
+
+  files = [
+    "naming/naming_heap.ml"
+    "naming/nast_eval.ml"
+    "naming/attributes.ml"
+    "naming/nastVisitor.ml"
+  ]
+end
+
+begin library "hh-typing"
+  requires += [ "hh-naming" ]
+  files = [
+    "typing/typing_env.ml"
+    "typing/typing_hooks.ml"
+    "typing/typing_print.ml"
+    "typing/nastCheck.ml"
+    "typing/nast_terminality.ml"
+    "typing/typeVisitor.ml"
+    "typing/typing_dependent_type.ml"
+    "typing/typing_expand.ml"
+    "typing/typing_generic.ml"
+    "typing/typing_utils.ml"
+    "typing/typing_subst.ml"
+    "typing/typing_phase.ml"
+    "typing/typing_instantiate.ml"
+    "typing/typing_taccess.ml"
+    "typing/typing_tdef.ml"
+    "typing/typing_unification_env.ml"
+    "typing/typing_unify.ml"
+    "typing/typing_subtype.ml"
+    "typing/typing_ops.ml"
+    "typing/typing_suggest.ml"
+    "typing/nastInitCheck.ml"
+    "typing/typingEqualityCheck.ml"
+    "typing/typing_alias.ml"
+    "typing/typing_async.ml"
+    "typing/typing_enum.ml"
+    "typing/typing_hint.ml"
+    "typing/typing_extends.ml"
+    "typing/typing_exts.ml"
+    "typing/typing_lenv.ml"
+    "typing/typing_shapes.ml"
+    "typing/typing_variance.ml"
+    "typing/typing_sequencing.ml"
+    "typing/typing.ml"
+    "typing/typing_dynamic_yield.ml"
+    "typing/typing_inherit.ml"
+    "typing/typing_decl.ml"
+    "typing/typing_decl_service.ml"
+    "typing/typing_check_service.ml"
+    "typing/typing_check_utils.ml"
+    "typing/typing_compare.ml"
+    "typing/coverage_level.ml"
+    "typing/typing_redecl_service.ml"
+    "typing/typing_suggest_service.ml"
+  ]
+end
+
+begin library "hh-search"
+  requires += [ "hh-utils" "hh-heap"  "hh-parsing" ]
+  files = [
+    "search/searchUtils.ml"
+    "search/fuzzySearchService.ml"
+    "search/trieSearchService.ml"
+    "search/searchService.ml"
+    "search/hackSearchService.ml"
+  ]
+end
+
+begin library "hh-stubs-ai"
+  requires += [ "hh-typing-base" ]
+  files = [
+    "stubs/ai.ml"
+  ]
+end
+
+begin library "hh-socket"
+  requires += [ "hh-utils" ]
+  files = [
+    "socket/socket.ml"
+  ]
+end
+
+begin library "hh-hhi"
+  requires += [ "hh-globals" "hh-utils" ]
+  files = [
+    "hhi/hhi_elf.c"
+    "hhi/hhi.ml"
+  ]
+end
+
+begin library "hh-server-base"
+  requires += [ "hh-third-party" "hh-utils" "hh-typing"  "hh-search"
+                "hh-stubs" "hh-stubs-ai"  "hh-socket" "hh-dfind" "hh-hhi" ]
+  files = [
+    "server/serverConfig.ml"
+    "server/serverArgs.ml"
+    "server/serverEnv.ml"
+    "server/serverUtils.ml"
+    "server/argumentInfoService.ml"
+    "server/autocompleteService.ml"
+    "server/fileOutline.ml"
+    "server/serverIdeUtils.ml"
+    "server/findRefsService.ml"
+    "server/findUtils.ml"
+    "server/identifySymbolService.ml"
+    "server/inferAtPosService.ml"
+    "server/methodJumps.ml"
+    "server/serverArgumentInfo.ml"
+    "server/serverAutoComplete.ml"
+    "server/serverBuild.ml"
+    "server/serverCheckpoint.ml"
+    "server/serverColorFile.ml"
+    "server/serverCoverageMetric.ml"
+    "server/serverError.ml"
+    "server/serverFindRefs.ml"
+    "server/serverIdentifyFunction.ml"
+    "server/serverInferType.ml"
+    "server/serverLint.ml"
+    "server/serverRefactor.ml"
+    "server/serverSearch.ml"
+    "server/symbolUtils.ml"
+    "server/symbolFunCallService.ml"
+    "server/symbolTypeService.ml"
+    "server/symbolInfoService.ml"
+    "server/serverRpc.ml"
+    "server/serverTypeCheck.ml"
+    "server/serverCommand.ml"
+    "server/serverConvert.ml"
+  ]
+end
+
+begin library "hh-server"
+  requires += [
+    "hh-third-party" "hh-utils" "hh-typing"
+    "hh-search"  "hh-stubs"  "hh-stubs-ai"
+    "hh-socket"  "hh-dfind" "hh-server-base"
+  ]
+  files = [
+    "server/serverEnvBuild.ml"
+    "server/serverPeriodical.ml"
+    "server/serverInit.ml"
+    "server/serverMain.ml"
+  ]
+end
+
+begin library "hh-client"
+  requires += [
+    "hh-deps"  "hh-heap"  "hh-parsing"
+    "hh-globals"  "hh-search"  "hh-stubs"
+    "hh-socket"  "hh-server-base"
+  ]
+  files = [
+    "client/clientConnectSimple.ml"
+    "client/clientStop.ml"
+    "client/hackClientStop.ml"
+    "client/clientStart.ml"
+    "client/clientConnect.ml"
+    "client/clientLogCommand.ml"
+    "client/clientBuild.ml"
+    "client/clientEnv.ml"
+    "client/clientCommand.ml"
+    "client/clientArgs.ml"
+    "client/clientArgumentInfo.ml"
+    "client/clientAutocomplete.ml"
+    "client/clientCheckStatus.ml"
+    "client/colorFile.ml"
+    "client/clientColorFile.ml"
+    "client/clientCoverageMetric.ml"
+    "client/clientFindRefs.ml"
+    "client/clientLint.ml"
+    "client/clientMethodJumps.ml"
+    "client/clientOutline.ml"
+    "client/clientRefactor.ml"
+    "client/clientSearch.ml"
+    "client/clientSymbolInfo.ml"
+    "client/clientTypeAtPos.ml"
+    "client/clientCheck.ml"
+    "client/clientLogCommandUtils.ml"
+    "client/clientRestart.ml"
+  ]
+end
+
+begin program "hh_client"
+  requires += [ "hh-client" ]
+  files = [ "hh_client.ml" ]
+end
+
+begin program "hh_server"
+  requires += [ "hh-server" ]
+  files = [ "hh_server.ml" ]
+end
+
+begin library "hh-emitter"
+  requires += [ "hh-naming" ]
+
+  files = [
+    "emitter/emitter_core.ml"
+    "emitter/emitter_consts.ml"
+    "emitter/emitter_expr.ml"
+    "emitter/emitter_lit.ml"
+    "emitter/emitter_stmt.ml"
+    "emitter/emitter.ml"
+  ]
+end
+
+begin library "hh-format"
+  requires += [ "hh-typing-base" ]
+  files = [
+    "stubs/formatEventLogger.ml"
+    "format/format_hack.ml"
+    "format/format_diff.ml"
+    "format/format_mode.ml"
+  ]
+end
+
+begin program "hh_format"
+  requires += [ "hh-format" "hh-client" ]
+  files = [ "hh_format.ml" ]
+end
+
+begin program "hh_single_type_check"
+  requires += [ "hh-client"  "hh-emitter" ]
+  files = [
+    "hh_single_type_check.ml"
+  ]
+end
diff --git a/hphp/hack/src/fsnotify_win/fsnotify.ml b/hphp/hack/src/fsnotify_win/fsnotify.ml
new file mode 100644
index 00000000000000..41b0aab34467cb
--- /dev/null
+++ b/hphp/hack/src/fsnotify_win/fsnotify.ml
@@ -0,0 +1,28 @@
+(**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+exception Error of string * int
+
+type event = {
+  path : string; (* The full path for the file/directory that changed *)
+  wpath : string; (* The watched path that triggered this event *)
+}
+
+type fd_select = Unix.file_descr * (unit -> unit)
+
+type watch
+
+type env
+
+let init roots = assert false
+
+let add_watch env path = assert false
+
+let select env ?(read_fdl=[]) ?(write_fdl=[]) ~timeout callback = assert false
diff --git a/hphp/hack/src/fsnotify_win/fsnotify.mli b/hphp/hack/src/fsnotify_win/fsnotify.mli
new file mode 100644
index 00000000000000..f28dce9830048c
--- /dev/null
+++ b/hphp/hack/src/fsnotify_win/fsnotify.mli
@@ -0,0 +1,42 @@
+(**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+exception Error of string * int
+
+(* Contains all the fsevents context *)
+type env
+
+(* A subscription to events for a directory *)
+type watch
+
+type event = {
+  path : string; (* The full path for the file/directory that changed *)
+  wpath : string; (* The watched path that triggered this event *)
+}
+
+val init : string list -> env
+
+(* Returns None if we're already watching that path and Some watch otherwise *)
+val add_watch : env -> string -> watch option
+
+(* A file descriptor and what to do when it is selected *)
+type fd_select = Unix.file_descr * (unit -> unit)
+val select :
+  (* The fsevents context *)
+  env ->
+  (* Additional file descriptor to select for reading *)
+  ?read_fdl:(fd_select list) ->
+  (* Additional file descriptor to select for writing *)
+  ?write_fdl:(fd_select list) ->
+  (* Timeout...like Unix.select *)
+  timeout:float ->
+  (* The callback for file system events *)
+  (event list -> unit) ->
+  unit
diff --git a/hphp/hack/src/h2tp/build.ocp b/hphp/hack/src/h2tp/build.ocp
new file mode 100644
index 00000000000000..db2cbf7871dd7a
--- /dev/null
+++ b/hphp/hack/src/h2tp/build.ocp
@@ -0,0 +1,50 @@
+(**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+(* This file is separated from the other sources of Hack, because the
+   h2tp/ sub-directory is not copied to the Flow tree. Consequently,
+   we moved its description here so that ocp-build will not complain
+   about these missing files.
+*)
+
+begin program "h2tp"
+
+  requires += [ "hh-format" ]
+
+  files = [
+    "Prepend_require.ml"
+    "common/fun.ml"
+    "common/Str_ext.ml"
+    "common/ast_ext.ml"
+    "common/common_exns.ml"
+    "common/converter_options.ml"
+    "common/sys_ext.ml"
+    "common/parser_hack_ext.ml"
+    "mapper/map_ast.ml"
+    "mapper/Deleted_constructs.ml"
+    "mapper/constructor_arg_promotion.ml"
+    "mapper/detect_collections.ml"
+    "mapper/empty_collection_as_bool.ml"
+    "mapper/enum.ml"
+    "mapper/erase_types.ml"
+    "mapper/hack_variadic.ml"
+    "mapper/initializer_expressions.ml"
+    "mapper/lambda_expressions.ml"
+    "mapper/misc.ml"
+    "mapper/ref_collections.ml"
+    "mapper/unsupported_constructs.ml"
+    "mapper/value_collections.ml"
+    "mapper/yield_break.ml"
+    "unparser/unparsed.ml"
+    "unparser/unparser.ml"
+    "engine.ml"
+    "h2tp.ml"
+  ]
+end
diff --git a/hphp/hack/src/heap/hh_shared.c b/hphp/hack/src/heap/hh_shared.c
index 429ab80c4483b5..866f0ccfc93975 100644
--- a/hphp/hack/src/heap/hh_shared.c
+++ b/hphp/hack/src/heap/hh_shared.c
@@ -76,13 +76,16 @@
  */
 /*****************************************************************************/
 
+
+#include <caml/memory.h>
+#include <caml/alloc.h>
+#include <caml/fail.h>
+
+#ifndef _WIN32
 /* define CAML_NAME_SPACE to ensure all the caml imports are prefixed with
  * 'caml_' */
 #define CAML_NAME_SPACE
 #include <assert.h>
-#include <caml/memory.h>
-#include <caml/alloc.h>
-#include <caml/fail.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
@@ -95,13 +98,13 @@
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
-#include <unistd.h>
-
 #ifndef NO_LZ4
 #include <lz4.h>
 #include <lz4hc.h>
 #endif
 
+#include <unistd.h>
+
 /*****************************************************************************/
 /* Config settings (essentially constants, so they don't need to live in shared
  * memory), initialized in hh_shared_init */
@@ -999,3 +1002,81 @@ void hh_remove(value key) {
   assert(hashtbl[slot].hash == get_hash(key));
   hashtbl[slot].addr = NULL;
 }
+
+#else // _WIN32
+// CAGO: some of theses functions will be the same as in linux version
+
+void hh_add(value key, value data) {}
+void hh_add_dep(value ocaml_dep) {}
+void hh_call_after_init() {}
+void hh_collect() {}
+void hh_move(value key1, value key2) {}
+void hh_remove(value key) {}
+void hh_save(value out_filename) {}
+void hh_shared_clear() {}
+void hh_shared_init(value global_size_val, value heap_size_val) {}
+void hh_load(value in_filename) {}
+void hh_shared_store(value data) {}
+void hh_worker_init() {}
+
+value hh_counter_next() {
+  CAMLparam0();
+  caml_failwith("'hh_counter_next` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_dep_slots() {
+  CAMLparam0();
+  caml_failwith("'hh_dep_slots` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_dep_used_slots() {
+  CAMLparam0();
+  caml_failwith("'hh_dep_used_slots` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_get(value key) {
+  CAMLparam1(key);
+  caml_failwith("'hh_get` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_get_dep(value dep) {
+  CAMLparam1(dep);
+  caml_failwith("'hh_get_dep` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_hash_slots() {
+  CAMLparam0();
+  caml_failwith("'hh_hash_slots` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_hash_used_slots() {
+  CAMLparam0();
+  caml_failwith("'hh_hash_used_slots` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_heap_size() {
+  CAMLparam0();
+  caml_failwith("'hh_heap_size` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_mem(value key) {
+  CAMLparam1(key);
+  caml_failwith("'hh_mem` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+value hh_shared_load() {
+  CAMLparam0();
+  caml_failwith("'hh_shared_load` is not implemented in `hh_shared.c`.");
+  CAMLreturn(Val_unit);
+}
+
+#endif
diff --git a/hphp/hack/src/hhi/hhi_elf.c b/hphp/hack/src/hhi/hhi_elf.c
index fc543ca6de6b23..991da84b504aa8 100644
--- a/hphp/hack/src/hhi/hhi_elf.c
+++ b/hphp/hack/src/hhi/hhi_elf.c
@@ -8,8 +8,11 @@
  *
  */
 
+
 #include <caml/memory.h>
 #include <caml/alloc.h>
+
+#ifndef _WIN32
 #include <fcntl.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -149,3 +152,12 @@ value get_embedded_hhi_data(value filename) {
 }
 
 #endif
+
+#else
+#include <caml/fail.h>
+value get_embedded_hhi_data(value filename) {
+  CAMLparam1(filename);
+  caml_failwith("'get_embedded_hhi_data` is not implemented in `hhi_elf.c`.");
+  CAMLreturn(Val_unit);
+}
+#endif
diff --git a/hphp/hack/src/scripts/gen_build_id.ml b/hphp/hack/src/scripts/gen_build_id.ml
new file mode 100644
index 00000000000000..9bd42727c6bb02
--- /dev/null
+++ b/hphp/hack/src/scripts/gen_build_id.ml
@@ -0,0 +1,66 @@
+(**
+ * Copyright (c) 2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the "hack" directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ *)
+
+let with_pipe f =
+  let fd_r, fd_w = Unix.pipe () in
+  try
+    let res = f fd_r fd_w in
+    Unix.close fd_r;
+    Unix.close fd_w;
+    res
+  with exn ->
+    Unix.close fd_r;
+    Unix.close fd_w;
+    raise exn
+
+let with_in_channel filename f =
+  let ic = open_in_bin filename in
+  try let res = f ic in close_in ic; res
+  with exn -> close_in ic; raise exn
+
+let with_out_channel filename f =
+  let oc = open_out_bin filename in
+  try let res = f oc in close_out oc; res
+  with exn -> close_out oc; raise exn
+
+(* Read the first line in stdout or stderr of an external command. *)
+let read_process_output name args =
+  with_pipe @@ fun in_r in_w ->
+  with_pipe @@ fun out_r out_w ->
+  let pid = Unix.create_process name args in_r out_w out_w in
+  let out_inch = Unix.in_channel_of_descr out_r in
+  let line = input_line out_inch in
+  match Unix.waitpid [] pid with
+  | _, Unix.WEXITED 0 -> line
+  | _ -> exit 1
+
+let string_of_file filename =
+  with_in_channel filename @@ fun ic ->
+  let s = String.create 32759 in
+  let b = Buffer.create 1000 in
+  let rec iter ic b s =
+    let nread = input ic s 0 32759 in
+    if nread > 0 then begin
+      Buffer.add_substring b s 0 nread;
+      iter ic b s
+    end in
+  iter ic b s;
+  Buffer.contents b
+
+let () =
+  let out_file = Sys.argv.(1) in
+  let rev = read_process_output "git" [|"git"; "rev-parse"; "HEAD"|] in
+  let content =
+    Printf.sprintf "const char* const BuildInfo_kRevision = %S;\n" rev in
+  let do_dump =
+    not (Sys.file_exists out_file) || string_of_file out_file <> content in
+  if do_dump then
+    with_out_channel out_file @@ fun oc ->
+    output_string oc content
diff --git a/hphp/hack/src/utils/nproc.c b/hphp/hack/src/utils/nproc.c
index 953d3761f335cb..c03f3411ede31f 100644
--- a/hphp/hack/src/utils/nproc.c
+++ b/hphp/hack/src/utils/nproc.c
@@ -7,13 +7,23 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  */
+
 #include <caml/memory.h>
+#ifdef _WIN32
+#include <windows.h>
+#else
 #include <unistd.h>
+#endif
 
 value nproc(void) {
   CAMLparam0();
   CAMLlocal1(result);
-
+#ifdef _WIN32
+  SYSTEM_INFO sysinfo;
+  GetSystemInfo(&sysinfo);
+  result = Val_long(sysinfo.dwNumberOfProcessors);
+#else
   result = Val_long(sysconf(_SC_NPROCESSORS_ONLN));
+#endif
   CAMLreturn(result);
 }
diff --git a/hphp/hack/src/utils/realpath.c b/hphp/hack/src/utils/realpath.c
index 81fa475304cd68..cb5ab5840e63e4 100644
--- a/hphp/hack/src/utils/realpath.c
+++ b/hphp/hack/src/utils/realpath.c
@@ -7,12 +7,16 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  */
+
+
 #include <caml/mlvalues.h>
 #include <caml/memory.h>
 #include <caml/alloc.h>
 #include <limits.h>
 #include <stdlib.h>
 
+#ifndef _WIN32
+
 #define Val_none Val_int(0)
 
 static value
@@ -41,3 +45,16 @@ hh_realpath(value v) {
     CAMLreturn(Val_some(caml_copy_string(output)));
   }
 }
+
+#else
+
+#include <caml/fail.h>
+
+CAMLprim value
+hh_realpath(value v) {
+  CAMLparam1(v);
+  caml_failwith("TODO: 'hh_realpath` is not implemented in `realpath.c`.");
+  CAMLreturn(Val_unit);
+}
+
+#endif