diff --git a/Externals/zlib/CMakeLists.txt b/Externals/zlib/CMakeLists.txt
index 0c0247cc51..cb45d91b0e 100644
--- a/Externals/zlib/CMakeLists.txt
+++ b/Externals/zlib/CMakeLists.txt
@@ -1,36 +1,18 @@
-cmake_minimum_required(VERSION 2.4.4)
-set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS ON)
-
 project(zlib C)
 
-set(VERSION "1.2.8")
-
-option(ASM686 "Enable building i686 assembly implementation")
-option(AMD64 "Enable building amd64 assembly implementation")
-
-set(INSTALL_BIN_DIR "${CMAKE_INSTALL_PREFIX}/bin" CACHE PATH "Installation directory for executables")
-set(INSTALL_LIB_DIR "${CMAKE_INSTALL_PREFIX}/lib" CACHE PATH "Installation directory for libraries")
-set(INSTALL_INC_DIR "${CMAKE_INSTALL_PREFIX}/include" CACHE PATH "Installation directory for headers")
-set(INSTALL_MAN_DIR "${CMAKE_INSTALL_PREFIX}/share/man" CACHE PATH "Installation directory for manual pages")
-set(INSTALL_PKGCONFIG_DIR "${CMAKE_INSTALL_PREFIX}/share/pkgconfig" CACHE PATH "Installation directory for pkgconfig (.pc) files")
-
 include(CheckTypeSize)
 include(CheckFunctionExists)
 include(CheckIncludeFile)
 include(CheckCSourceCompiles)
-enable_testing()
 
 check_include_file(sys/types.h HAVE_SYS_TYPES_H)
 check_include_file(stdint.h    HAVE_STDINT_H)
 check_include_file(stddef.h    HAVE_STDDEF_H)
+check_include_file(unistd.h Z_HAVE_UNISTD_H)
 
-#
 # Check to see if we have large file support
-#
 set(CMAKE_REQUIRED_DEFINITIONS -D_LARGEFILE64_SOURCE=1)
-# We add these other definitions here because CheckTypeSize.cmake
-# in CMake 2.4.x does not automatically do so and we want
-# compatibility with CMake 2.4.x.
+
 if(HAVE_SYS_TYPES_H)
     list(APPEND CMAKE_REQUIRED_DEFINITIONS -DHAVE_SYS_TYPES_H)
 endif()
@@ -46,52 +28,23 @@ if(HAVE_OFF64_T)
 endif()
 set(CMAKE_REQUIRED_DEFINITIONS) # clear variable
 
-#
 # Check for fseeko
-#
 check_function_exists(fseeko HAVE_FSEEKO)
 if(NOT HAVE_FSEEKO)
     add_definitions(-DNO_FSEEKO)
 endif()
 
-#
-# Check for unistd.h
-#
-check_include_file(unistd.h Z_HAVE_UNISTD_H)
-
 if(MSVC)
-    set(CMAKE_DEBUG_POSTFIX "d")
     add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
     add_definitions(-D_CRT_NONSTDC_NO_DEPRECATE)
-    include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 endif()
 
-if(NOT CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_CURRENT_BINARY_DIR)
-    # If we're doing an out of source build and the user has a zconf.h
-    # in their source tree...
-    if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h)
-        message(STATUS "Renaming")
-        message(STATUS "    ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h")
-        message(STATUS "to 'zconf.h.included' because this file is included with zlib")
-        message(STATUS "but CMake generates it automatically in the build directory.")
-        file(RENAME ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h.included)
-  endif()
-endif()
-
-set(ZLIB_PC ${CMAKE_CURRENT_BINARY_DIR}/zlib.pc)
-configure_file( ${CMAKE_CURRENT_SOURCE_DIR}/zlib.pc.cmakein
-		${ZLIB_PC} @ONLY)
-configure_file(	${CMAKE_CURRENT_SOURCE_DIR}/zconf.h.cmakein
-		${CMAKE_CURRENT_BINARY_DIR}/zconf.h @ONLY)
-include_directories(${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_SOURCE_DIR})
-
-
 #============================================================================
 # zlib
 #============================================================================
 
 set(ZLIB_PUBLIC_HDRS
-    ${CMAKE_CURRENT_BINARY_DIR}/zconf.h
+    zconf.h
     zlib.h
 )
 set(ZLIB_PRIVATE_HDRS
@@ -123,127 +76,4 @@ set(ZLIB_SRCS
     zutil.c
 )
 
-if(NOT MINGW)
-    set(ZLIB_DLL_SRCS
-        win32/zlib1.rc # If present will override custom build rule below.
-    )
-endif()
-
-if(CMAKE_COMPILER_IS_GNUCC)
-    if(ASM686)
-        set(ZLIB_ASMS contrib/asm686/match.S)
-    elseif (AMD64)
-        set(ZLIB_ASMS contrib/amd64/amd64-match.S)
-    endif ()
-
-	if(ZLIB_ASMS)
-		add_definitions(-DASMV)
-		set_source_files_properties(${ZLIB_ASMS} PROPERTIES LANGUAGE C COMPILE_FLAGS -DNO_UNDERLINE)
-	endif()
-endif()
-
-if(MSVC)
-    if(ASM686)
-		ENABLE_LANGUAGE(ASM_MASM)
-        set(ZLIB_ASMS
-			contrib/masmx86/inffas32.asm
-			contrib/masmx86/match686.asm
-		)
-    elseif (AMD64)
-		ENABLE_LANGUAGE(ASM_MASM)
-        set(ZLIB_ASMS
-			contrib/masmx64/gvmat64.asm
-			contrib/masmx64/inffasx64.asm
-		)
-    endif()
-
-	if(ZLIB_ASMS)
-		add_definitions(-DASMV -DASMINF)
-	endif()
-endif()
-
-# parse the full version number from zlib.h and include in ZLIB_FULL_VERSION
-file(READ ${CMAKE_CURRENT_SOURCE_DIR}/zlib.h _zlib_h_contents)
-string(REGEX REPLACE ".*#define[ \t]+ZLIB_VERSION[ \t]+\"([-0-9A-Za-z.]+)\".*"
-    "\\1" ZLIB_FULL_VERSION ${_zlib_h_contents})
-
-if(MINGW)
-    # This gets us DLL resource information when compiling on MinGW.
-    if(NOT CMAKE_RC_COMPILER)
-        set(CMAKE_RC_COMPILER windres.exe)
-    endif()
-
-    add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/zlib1rc.obj
-                       COMMAND ${CMAKE_RC_COMPILER}
-                            -D GCC_WINDRES
-                            -I ${CMAKE_CURRENT_SOURCE_DIR}
-                            -I ${CMAKE_CURRENT_BINARY_DIR}
-                            -o ${CMAKE_CURRENT_BINARY_DIR}/zlib1rc.obj
-                            -i ${CMAKE_CURRENT_SOURCE_DIR}/win32/zlib1.rc)
-    set(ZLIB_DLL_SRCS ${CMAKE_CURRENT_BINARY_DIR}/zlib1rc.obj)
-endif(MINGW)
-
-add_library(zlib SHARED ${ZLIB_SRCS} ${ZLIB_ASMS} ${ZLIB_DLL_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
-add_library(zlibstatic STATIC ${ZLIB_SRCS} ${ZLIB_ASMS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
-set_target_properties(zlib PROPERTIES DEFINE_SYMBOL ZLIB_DLL)
-set_target_properties(zlib PROPERTIES SOVERSION 1)
-
-if(NOT CYGWIN)
-    # This property causes shared libraries on Linux to have the full version
-    # encoded into their final filename.  We disable this on Cygwin because
-    # it causes cygz-${ZLIB_FULL_VERSION}.dll to be created when cygz.dll
-    # seems to be the default.
-    #
-    # This has no effect with MSVC, on that platform the version info for
-    # the DLL comes from the resource file win32/zlib1.rc
-    set_target_properties(zlib PROPERTIES VERSION ${ZLIB_FULL_VERSION})
-endif()
-
-if(UNIX)
-    # On unix-like platforms the library is almost always called libz
-   set_target_properties(zlib zlibstatic PROPERTIES OUTPUT_NAME z)
-   if(NOT APPLE)
-     set_target_properties(zlib PROPERTIES LINK_FLAGS "-Wl,--version-script,\"${CMAKE_CURRENT_SOURCE_DIR}/zlib.map\"")
-   endif()
-elseif(BUILD_SHARED_LIBS AND WIN32)
-    # Creates zlib1.dll when building shared library version
-    set_target_properties(zlib PROPERTIES SUFFIX "1.dll")
-endif()
-
-if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
-    install(TARGETS zlib zlibstatic
-        RUNTIME DESTINATION "${INSTALL_BIN_DIR}"
-        ARCHIVE DESTINATION "${INSTALL_LIB_DIR}"
-        LIBRARY DESTINATION "${INSTALL_LIB_DIR}" )
-endif()
-if(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL )
-    install(FILES ${ZLIB_PUBLIC_HDRS} DESTINATION "${INSTALL_INC_DIR}")
-endif()
-if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
-    install(FILES zlib.3 DESTINATION "${INSTALL_MAN_DIR}/man3")
-endif()
-if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
-    install(FILES ${ZLIB_PC} DESTINATION "${INSTALL_PKGCONFIG_DIR}")
-endif()
-
-#============================================================================
-# Example binaries
-#============================================================================
-
-add_executable(example test/example.c)
-target_link_libraries(example zlib)
-add_test(example example)
-
-add_executable(minigzip test/minigzip.c)
-target_link_libraries(minigzip zlib)
-
-if(HAVE_OFF64_T)
-    add_executable(example64 test/example.c)
-    target_link_libraries(example64 zlib)
-    set_target_properties(example64 PROPERTIES COMPILE_FLAGS "-D_FILE_OFFSET_BITS=64")
-    add_test(example64 example64)
-
-    add_executable(minigzip64 test/minigzip.c)
-    target_link_libraries(minigzip64 zlib)
-    set_target_properties(minigzip64 PROPERTIES COMPILE_FLAGS "-D_FILE_OFFSET_BITS=64")
-endif()
+add_library(libz STATIC ${ZLIB_SRCS} ${ZLIB_DLL_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})