--- a/Makefile.in
+++ b/Makefile.in
@@ -48,16 +48,19 @@ endif
 
 ifdef MOZ_MEMORY
 tier_base_dirs += memory/mozjemalloc
 ifdef MOZ_JEMALLOC
 tier_base_dirs += memory/jemalloc
 endif
 tier_base_dirs += memory/build
 endif
+ifndef MOZ_NATIVE_ZLIB
+tier_base_dirs += modules/zlib
+endif
 tier_base_dirs += \
   mozglue \
   memory/mozalloc \
   $(NULL)
 endif
 
 ifdef COMPILE_ENVIRONMENT
 include $(topsrcdir)/$(MOZ_BUILD_APP)/build.mk

--- a/aclocal.m4
+++ b/aclocal.m4
@@ -14,16 +14,17 @@ builtin(include, build/autoconf/mozcommo
 builtin(include, build/autoconf/acwinpaths.m4)dnl
 builtin(include, build/autoconf/lto.m4)dnl
 builtin(include, build/autoconf/gcc-pr49911.m4)dnl
 builtin(include, build/autoconf/frameptr.m4)dnl
 builtin(include, build/autoconf/compiler-opts.m4)dnl
 builtin(include, build/autoconf/expandlibs.m4)dnl
 builtin(include, build/autoconf/arch.m4)dnl
 builtin(include, build/autoconf/android.m4)dnl
+builtin(include, build/autoconf/zlib.m4)dnl
 
 MOZ_PROG_CHECKMSYS()
 
 # Read the user's .mozconfig script.  We can't do this in
 # configure.in: autoconf puts the argument parsing code above anything
 # expanded from configure.in, and we need to get the configure options
 # from .mozconfig in place before that argument parsing code.
 MOZ_READ_MOZCONFIG(.)

new file mode 100644
--- /dev/null
+++ b/build/autoconf/zlib.m4
@@ -0,0 +1,54 @@
+dnl This Source Code Form is subject to the terms of the Mozilla Public
+dnl License, v. 2.0. If a copy of the MPL was not distributed with this
+dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+dnl Usage: MOZ_ZLIB_CHECK([version])
+
+AC_DEFUN([MOZ_ZLIB_CHECK],
+[
+
+MOZZLIB=$1
+
+MOZ_ARG_WITH_STRING(system-zlib,
+[  --with-system-zlib[=PFX]
+                          Use system libz [installed at prefix PFX]],
+    ZLIB_DIR=$withval)
+
+if test -z "$MOZ_ZLIB_LIBS$MOZ_ZLIB_CFLAGS$SKIP_LIBRARY_CHECKS"; then
+    _SAVE_CFLAGS=$CFLAGS
+    _SAVE_LDFLAGS=$LDFLAGS
+    _SAVE_LIBS=$LIBS
+
+    if test -n "${ZLIB_DIR}" -a "${ZLIB_DIR}" != "yes"; then
+        MOZ_ZLIB_CFLAGS="-I${ZLIB_DIR}/include"
+        MOZ_ZLIB_LIBS="-L${ZLIB_DIR}/lib"
+        CFLAGS="$MOZ_ZLIB_CFLAGS $CFLAGS"
+        LDFLAGS="$MOZ_ZLIB_LIBS $LDFLAGS"
+    fi
+    if test -z "$ZLIB_DIR" -o "$ZLIB_DIR" = no; then
+        MOZ_NATIVE_ZLIB=
+    else
+        AC_CHECK_LIB(z, gzread, [MOZ_NATIVE_ZLIB=1 MOZ_ZLIB_LIBS="$MOZ_ZLIB_LIBS -lz"],
+            [MOZ_NATIVE_ZLIB=])
+        if test "$MOZ_NATIVE_ZLIB" = 1; then
+            MOZZLIBNUM=`echo $MOZZLIB | awk -F. changequote(<<, >>)'{printf "0x%x\n", (((<<$>>1 * 16 + <<$>>2) * 16) + <<$>>3) * 16 + <<$>>4}'changequote([, ])`
+            AC_TRY_COMPILE([ #include <stdio.h>
+                             #include <string.h>
+                             #include <zlib.h> ],
+                           [ #if ZLIB_VERNUM < $MOZZLIBNUM
+                             #error "Insufficient zlib version ($MOZZLIBNUM required)."
+                             #endif ],
+                           MOZ_NATIVE_ZLIB=1,
+                           AC_MSG_ERROR([Insufficient zlib version for --with-system-zlib ($MOZZLIB required)]))
+        fi
+    fi
+    CFLAGS=$_SAVE_CFLAGS
+    LDFLAGS=$_SAVE_LDFLAGS
+    LIBS=$_SAVE_LIBS
+fi
+
+AC_SUBST(MOZ_ZLIB_CFLAGS)
+AC_SUBST(MOZ_ZLIB_LIBS)
+AC_SUBST(MOZ_NATIVE_ZLIB)
+
+])

--- a/configure.in
+++ b/configure.in
@@ -49,17 +49,16 @@ dnl ====================================
 _SUBDIR_HOST_CXXFLAGS="$HOST_CXXFLAGS"
 _SUBDIR_HOST_LDFLAGS="$HOST_LDFLAGS"
 _SUBDIR_CONFIG_ARGS="$ac_configure_args"
 
 dnl Set the version number of the libs included with mozilla
 dnl ========================================================
 MOZJPEG=62
 MOZPNG=10511
-MOZZLIB=1.2.3
 NSPR_VERSION=4
 NSS_VERSION=3
 
 dnl Set the minimum version of toolkit libs used by mozilla
 dnl ========================================================
 GLIB_VERSION=1.2.0
 PERL_VERSION=5.006
 PYTHON_VERSION=2.5
@@ -1080,18 +1079,16 @@ ASM_SUFFIX=s
 IMPORT_LIB_SUFFIX=
 TARGET_MD_ARCH=unix
 DIRENT_INO=d_ino
 WIN_TOP_SRC=
 MOZ_USER_DIR=".mozilla"
 
 MOZ_JPEG_CFLAGS=
 MOZ_JPEG_LIBS='$(call EXPAND_LIBNAME_PATH,mozjpeg,$(DEPTH)/media/libjpeg)'
-MOZ_ZLIB_CFLAGS=
-MOZ_ZLIB_LIBS='$(call EXPAND_LIBNAME_PATH,mozz,$(DEPTH)/modules/zlib/src)'
 MOZ_BZ2_CFLAGS=
 MOZ_BZ2_LIBS='$(call EXPAND_LIBNAME_PATH,bz2,$(DEPTH)/modules/libbz2/src)'
 MOZ_PNG_CFLAGS=
 MOZ_PNG_LIBS='$(call EXPAND_LIBNAME_PATH,mozpng,$(DEPTH)/media/libpng)'
 
 MOZ_JS_STATIC_LIBS='$(call EXPAND_LIBNAME_PATH,js_static,$(LIBXUL_DIST)/lib)'
 MOZ_JS_SHARED_LIBS='$(call EXPAND_LIBNAME_PATH,mozjs,$(LIBXUL_DIST)/lib)'
 DYNAMIC_XPCOM_LIBS='-L$(LIBXUL_DIST)/bin -lxpcom -lxpcom_core -lmozalloc'
@@ -4029,61 +4026,32 @@ fi
 CFLAGS=$_SAVE_CFLAGS
 LDFLAGS=$_SAVE_LDFLAGS
 LIBS=$_SAVE_LIBS
 
 if test -n "${JPEG_DIR}" -a -d "${JPEG_DIR}" -a "$MOZ_NATIVE_JPEG" = 1; then
     MOZ_JPEG_CFLAGS="-I${JPEG_DIR}/include"
     MOZ_JPEG_LIBS="-L${JPEG_DIR}/lib ${MOZ_JPEG_LIBS}"
 fi
+fi # SKIP_LIBRARY_CHECKS
 
 dnl system ZLIB support
 dnl ========================================================
-MOZ_ARG_WITH_STRING(system-zlib,
-[  --with-system-zlib[=PFX]
-                          Use system libz [installed at prefix PFX]],
-    ZLIB_DIR=$withval)
-
-_SAVE_CFLAGS=$CFLAGS
-_SAVE_LDFLAGS=$LDFLAGS
-_SAVE_LIBS=$LIBS
-if test -n "${ZLIB_DIR}" -a "${ZLIB_DIR}" != "yes"; then
-    CFLAGS="-I${ZLIB_DIR}/include $CFLAGS"
-    LDFLAGS="-L${ZLIB_DIR}/lib $LDFLAGS"
-fi
-if test -z "$ZLIB_DIR" -o "$ZLIB_DIR" = no; then
-    MOZ_NATIVE_ZLIB=
-else
-    AC_CHECK_LIB(z, gzread, [MOZ_NATIVE_ZLIB=1 MOZ_ZLIB_LIBS="-lz"],
-	[MOZ_NATIVE_ZLIB=])
-fi
-if test "$MOZ_NATIVE_ZLIB" = 1; then
-    MOZZLIBNUM=`echo $MOZZLIB | awk -F. '{printf "0x%x\n", ((($1 * 16 + $2) * 16) + $3) * 16 + $4}'`
-    AC_TRY_COMPILE([ #include <stdio.h>
-                     #include <string.h>
-                     #include <zlib.h> ],
-                   [ #if ZLIB_VERNUM < $MOZZLIBNUM
-                     #error "Insufficient zlib version ($MOZZLIBNUM required)."
-                     #endif ],
-                   MOZ_NATIVE_ZLIB=1,
-                   AC_MSG_ERROR([Insufficient zlib version for --with-system-zlib ($MOZZLIB required)]))
-fi
-CFLAGS=$_SAVE_CFLAGS
-LDFLAGS=$_SAVE_LDFLAGS
-LIBS=$_SAVE_LIBS
-
-if test "${ZLIB_DIR}" -a -d "${ZLIB_DIR}" -a "$MOZ_NATIVE_ZLIB" = 1; then
-    MOZ_ZLIB_CFLAGS="-I${ZLIB_DIR}/include"
-    MOZ_ZLIB_LIBS="-L${ZLIB_DIR}/lib ${ZLIB_LIBS}"
+MOZ_ZLIB_CHECK([1.2.3])
+
+if test "$MOZ_NATIVE_ZLIB" != 1; then
+    MOZ_ZLIB_CFLAGS=
+    MOZ_ZLIB_LIBS='$(call EXPAND_LIBNAME_PATH,mozz,'"$_objdir"'/modules/zlib/src)'
 fi
 
 if test "$MOZ_LINKER" = 1 -a "$MOZ_NATIVE_ZLIB" != 1; then
     AC_MSG_ERROR([Custom dynamic linker requires --with-system-zlib])
 fi
 
+if test -z "$SKIP_LIBRARY_CHECKS"; then
 dnl system BZIP2 Support
 dnl ========================================================
 MOZ_ARG_WITH_STRING(system-bz2,
 [  --with-system-bz2[=PFX]
                           Use system libbz2 [installed at prefix PFX]],
     BZ2_DIR=$withval)
 
 _SAVE_CFLAGS=$CFLAGS
@@ -8519,24 +8487,21 @@ COMPILE_CXXFLAGS=`echo \
     $_DEFINES_CXXFLAGS \
 	$_DEPEND_CFLAGS \
     $COMPILE_CXXFLAGS`
 
 AC_SUBST(MOZ_NATIVE_MAKEDEPEND)
 AC_SUBST(SYSTEM_LIBXUL)
 AC_SUBST(MOZ_NATIVE_JPEG)
 AC_SUBST(MOZ_NATIVE_PNG)
-AC_SUBST(MOZ_NATIVE_ZLIB)
 AC_SUBST(MOZ_NATIVE_BZ2)
 
 AC_SUBST(MOZ_FLEXBOX)
 AC_SUBST(MOZ_JPEG_CFLAGS)
 AC_SUBST(MOZ_JPEG_LIBS)
-AC_SUBST(MOZ_ZLIB_CFLAGS)
-AC_SUBST(MOZ_ZLIB_LIBS)
 AC_SUBST(MOZ_BZ2_CFLAGS)
 AC_SUBST(MOZ_BZ2_LIBS)
 AC_SUBST(MOZ_PNG_CFLAGS)
 AC_SUBST(MOZ_PNG_LIBS)
 
 AC_SUBST(NSPR_CFLAGS)
 AC_SUBST(NSPR_LIBS)
 AC_SUBST(MOZ_NATIVE_NSPR)
@@ -9182,16 +9147,22 @@ if test "$MOZ_MEMORY"; then
    ac_configure_args="$ac_configure_args --enable-jemalloc"
 fi
 if test -n "$MOZ_GLUE_LDFLAGS"; then
    export MOZ_GLUE_LDFLAGS
 fi
 if test -n "$MOZ_GLUE_PROGRAM_LDFLAGS"; then
    export MOZ_GLUE_PROGRAM_LDFLAGS
 fi
+if test "$MOZ_NATIVE_ZLIB" != 1 -a "$OS_ARCH" = "WINNT"; then
+   MOZ_ZLIB_LIBS=
+fi
+export MOZ_NATIVE_ZLIB
+export MOZ_ZLIB_CFLAGS
+export MOZ_ZLIB_LIBS
 export MOZ_APP_NAME
 export STLPORT_CPPFLAGS
 export STLPORT_LDFLAGS
 export STLPORT_LIBS
 AC_OUTPUT_SUBDIRS(js/src)
 ac_configure_args="$_SUBDIR_CONFIG_ARGS"
 
 fi # COMPILE_ENVIRONMENT && !LIBXUL_SDK_DIR

--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -660,16 +660,19 @@ ifdef MOZ_ETW
 RESFILE = ETWProvider.res
 endif
 
 # HP-UX does not require the extra linking of "-lm"
 ifeq (,$(filter HP-UX WINNT OS2,$(OS_ARCH)))
 EXTRA_LIBS	+= -lm
 endif
 
+CFLAGS += $(MOZ_ZLIB_CFLAGS)
+EXTRA_LIBS += $(MOZ_ZLIB_LIBS)
+
 # Prevent floating point errors caused by VC++ optimizations
 ifdef _MSC_VER
 # XXX We should add this to CXXFLAGS, too?
 CFLAGS += -fp:precise
 
 ifeq ($(CPU_ARCH),x86)
 # Workaround compiler bug on PGO (Bug 721284)
 MonoIC.$(OBJ_SUFFIX): CXXFLAGS += -GL-

--- a/js/src/aclocal.m4
+++ b/js/src/aclocal.m4
@@ -13,10 +13,11 @@ builtin(include, build/autoconf/mozcommo
 builtin(include, build/autoconf/acwinpaths.m4)dnl
 builtin(include, build/autoconf/lto.m4)dnl
 builtin(include, build/autoconf/gcc-pr49911.m4)dnl
 builtin(include, build/autoconf/frameptr.m4)dnl
 builtin(include, build/autoconf/compiler-opts.m4)dnl
 builtin(include, build/autoconf/expandlibs.m4)dnl
 builtin(include, build/autoconf/arch.m4)dnl
 builtin(include, build/autoconf/android.m4)dnl
+builtin(include, build/autoconf/zlib.m4)dnl
 
 MOZ_PROG_CHECKMSYS()

new file mode 100644
--- /dev/null
+++ b/js/src/build/autoconf/zlib.m4
@@ -0,0 +1,54 @@
+dnl This Source Code Form is subject to the terms of the Mozilla Public
+dnl License, v. 2.0. If a copy of the MPL was not distributed with this
+dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+dnl Usage: MOZ_ZLIB_CHECK([version])
+
+AC_DEFUN([MOZ_ZLIB_CHECK],
+[
+
+MOZZLIB=$1
+
+MOZ_ARG_WITH_STRING(system-zlib,
+[  --with-system-zlib[=PFX]
+                          Use system libz [installed at prefix PFX]],
+    ZLIB_DIR=$withval)
+
+if test -z "$MOZ_ZLIB_LIBS$MOZ_ZLIB_CFLAGS$SKIP_LIBRARY_CHECKS"; then
+    _SAVE_CFLAGS=$CFLAGS
+    _SAVE_LDFLAGS=$LDFLAGS
+    _SAVE_LIBS=$LIBS
+
+    if test -n "${ZLIB_DIR}" -a "${ZLIB_DIR}" != "yes"; then
+        MOZ_ZLIB_CFLAGS="-I${ZLIB_DIR}/include"
+        MOZ_ZLIB_LIBS="-L${ZLIB_DIR}/lib"
+        CFLAGS="$MOZ_ZLIB_CFLAGS $CFLAGS"
+        LDFLAGS="$MOZ_ZLIB_LIBS $LDFLAGS"
+    fi
+    if test -z "$ZLIB_DIR" -o "$ZLIB_DIR" = no; then
+        MOZ_NATIVE_ZLIB=
+    else
+        AC_CHECK_LIB(z, gzread, [MOZ_NATIVE_ZLIB=1 MOZ_ZLIB_LIBS="$MOZ_ZLIB_LIBS -lz"],
+            [MOZ_NATIVE_ZLIB=])
+        if test "$MOZ_NATIVE_ZLIB" = 1; then
+            MOZZLIBNUM=`echo $MOZZLIB | awk -F. changequote(<<, >>)'{printf "0x%x\n", (((<<$>>1 * 16 + <<$>>2) * 16) + <<$>>3) * 16 + <<$>>4}'changequote([, ])`
+            AC_TRY_COMPILE([ #include <stdio.h>
+                             #include <string.h>
+                             #include <zlib.h> ],
+                           [ #if ZLIB_VERNUM < $MOZZLIBNUM
+                             #error "Insufficient zlib version ($MOZZLIBNUM required)."
+                             #endif ],
+                           MOZ_NATIVE_ZLIB=1,
+                           AC_MSG_ERROR([Insufficient zlib version for --with-system-zlib ($MOZZLIB required)]))
+        fi
+    fi
+    CFLAGS=$_SAVE_CFLAGS
+    LDFLAGS=$_SAVE_LDFLAGS
+    LIBS=$_SAVE_LIBS
+fi
+
+AC_SUBST(MOZ_ZLIB_CFLAGS)
+AC_SUBST(MOZ_ZLIB_LIBS)
+AC_SUBST(MOZ_NATIVE_ZLIB)
+
+])

--- a/js/src/config/Makefile.in
+++ b/js/src/config/Makefile.in
@@ -37,16 +37,21 @@ DIRS		+= mkdepend
 endif
 endif
 
 include $(topsrcdir)/config/config.mk
 
 # Do not install util programs
 NO_INSTALL=1
 
+# Force wrap zlib system header if building js as a shared library.
+ifdef JS_SHARED_LIBRARY
+DEFINES += -DMOZ_NATIVE_ZLIB=1
+endif
+
 include $(topsrcdir)/config/rules.mk
 
 HOST_CFLAGS += -DUNICODE -D_UNICODE
 
 export:: $(TARGETS)
 ifdef HOST_PROGRAM
 	$(INSTALL) $(HOST_PROGRAM) $(DIST)/bin
 endif

--- a/js/src/config/autoconf.mk.in
+++ b/js/src/config/autoconf.mk.in
@@ -187,16 +187,19 @@ DOXYGEN		= @DOXYGEN@
 PBBUILD_BIN	= @PBBUILD_BIN@
 SDP		= @SDP@
 NSINSTALL_BIN	= @NSINSTALL_BIN@
 
 NSPR_CONFIG	= @NSPR_CONFIG@
 NSPR_CFLAGS	= @NSPR_CFLAGS@
 NSPR_LIBS	= @NSPR_LIBS@
 
+MOZ_ZLIB_LIBS   = @MOZ_ZLIB_LIBS@
+MOZ_ZLIB_CFLAGS = @MOZ_ZLIB_CFLAGS@
+
 MOZ_NATIVE_FFI	= @MOZ_NATIVE_FFI@
 MOZ_FFI_LIBS	= @MOZ_FFI_LIBS@
 MOZ_FFI_CFLAGS	= @MOZ_FFI_CFLAGS@
 
 USE_DEPENDENT_LIBS = @USE_DEPENDENT_LIBS@
 
 JS_NATIVE_EDITLINE = @JS_NATIVE_EDITLINE@
 JS_DISABLE_SHELL   = @JS_DISABLE_SHELL@

--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -3320,16 +3320,24 @@ if test -n "$MOZ_NATIVE_NSPR"; then
                  #error PR_STATIC_ASSERT not defined
                  #endif],
                 [MOZ_NATIVE_NSPR=1],
                 AC_MSG_ERROR([system NSPR does not support PR_STATIC_ASSERT]))
     CFLAGS=$_SAVE_CFLAGS
 fi
 
 dnl ========================================================
+dnl system zlib Support
+dnl ========================================================
+dnl Standalone js defaults to system zlib
+ZLIB_DIR=yes
+
+MOZ_ZLIB_CHECK([1.2.3])
+
+dnl ========================================================
 dnl system libffi Support
 dnl ========================================================
 MOZ_ARG_ENABLE_BOOL(system-ffi,
 [  --enable-system-ffi       Use system libffi (located with pkgconfig)],
     MOZ_NATIVE_FFI=1 )
 
 if test -n "$MOZ_NATIVE_FFI"; then
     # Vanilla libffi 3.0.9 needs a few patches from upcoming version 3.0.10

--- a/js/src/jsapi-tests/Makefile.in
+++ b/js/src/jsapi-tests/Makefile.in
@@ -77,16 +77,16 @@ CSRCS = \
 #  testRegExpInstanceProperties.cpp \
 #  $(NULL)
 
 DEFINES         += -DEXPORT_JS_API
 # Building against js_static requires that we declare mfbt sybols "exported"
 # on its behalf.
 DEFINES         += -DIMPL_MFBT
 
-LIBS      = $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_SUFFIX) $(NSPR_LIBS)
+LIBS      = $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_SUFFIX) $(NSPR_LIBS) $(MOZ_ZLIB_LIBS)
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
 include $(topsrcdir)/config/rules.mk
 
 check::
 	$(wildcard $(RUN_TEST_PROGRAM)) $(DIST)/bin/jsapi-tests$(BIN_SUFFIX)

--- a/js/src/shell/Makefile.in
+++ b/js/src/shell/Makefile.in
@@ -18,17 +18,17 @@ CPPSRCS		= \
   jsheaptools.cpp \
   $(NULL)
 
 DEFINES         += -DEXPORT_JS_API
 # Building against js_static requires that we declare mfbt sybols "exported"
 # on its behalf.
 DEFINES         += -DIMPL_MFBT
 
-LIBS      = $(NSPR_LIBS) $(EDITLINE_LIBS) $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_SUFFIX)
+LIBS      = $(NSPR_LIBS) $(EDITLINE_LIBS) $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_SUFFIX) $(MOZ_ZLIB_LIBS)
 ifdef MOZ_NATIVE_FFI
 EXTRA_LIBS += $(MOZ_FFI_LIBS)
 endif
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
 ifeq ($(OS_ARCH),Darwin)
 ifeq ($(TARGET_CPU),x86_64)

--- a/layout/media/Makefile.in
+++ b/layout/media/Makefile.in
@@ -121,19 +121,16 @@ endif
 ifdef MOZ_ENABLE_SKIA
 SHARED_LIBRARY_LIBS += $(MOZ_SKIA_LIBS)
 endif
 
 ifeq (WINNT,$(OS_TARGET))
 EXTRA_DSO_LDOPTS = $(MOZALLOC_LIB) $(NSPR_LIBS)
 OS_LIBS += $(call EXPAND_LIBNAME,usp10 ole32)
 
-# OTS uses uncompress2() from libz, so we need to link with this
-EXTRA_DSO_LDOPTS += $(MOZ_ZLIB_LIBS)
-
 ifdef MOZ_WEBRTC
 EXTRA_DSO_LDOPTS += \
   -LIBPATH:"$(MOZ_DIRECTX_SDK_PATH)/lib/$(MOZ_DIRECTX_SDK_CPU_SUFFIX)" \
   $(NULL)
 OS_LIBS += $(call EXPAND_LIBNAME,secur32 crypt32 iphlpapi strmiids dmoguids wmcodecdspuuid amstrmid msdmo wininet)
 endif
 
 DEFFILE = symbols.def

--- a/media/libpng/Makefile.in
+++ b/media/libpng/Makefile.in
@@ -47,13 +47,12 @@ EXPORTS		= png.h pngconf.h mozpngconf.h
 
 LOCAL_INCLUDES	= -I$(srcdir)
 
 FORCE_STATIC_LIB = 1
 
 include $(topsrcdir)/config/rules.mk
 
 ifeq ($(OS_ARCH),WINNT)
-DEFINES		+= -DZLIB_DLL
 ifdef BUILD_DEBUG_GC
 DEFINES		+= -DDEBUG_GC
 endif
 endif

--- a/modules/libjar/Makefile.in
+++ b/modules/libjar/Makefile.in
@@ -33,12 +33,8 @@ LIBXUL_LIBRARY = 1
 
 CPPSRCS		= $(MODULES_LIBJAR_LCPPSRCS)
 
 XPIDLSRCS	= $(MODULES_LIBJAR_LXPIDLSRCS)
 
 EXPORTS		= $(MODULES_LIBJAR_LEXPORTS)
 
 include $(topsrcdir)/config/rules.mk
-
-ifeq ($(OS_ARCH),WINNT)
-DEFINES		+= -DZLIB_DLL=1
-endif

--- a/modules/zlib/src/Makefile.in
+++ b/modules/zlib/src/Makefile.in
@@ -8,22 +8,15 @@ topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 include $(srcdir)/objs.mk
 
 MODULE		= zlib
 LIBRARY_NAME	= mozz
-GRE_MODULE	= 1
-LIBXUL_LIBRARY = 1
-DIST_INSTALL = 1
-
-ifeq (,$(filter-out WINNT OS2,$(OS_ARCH)))
-DEFINES	+= -DZLIB_DLL=1
-endif
 
 CSRCS		= $(MODULES_ZLIB_SRC_LCSRCS)
 
 EXPORTS		= zlib.h zconf.h mozzconf.h
 
 
 include $(topsrcdir)/config/rules.mk

--- a/modules/zlib/src/mozzconf.h
+++ b/modules/zlib/src/mozzconf.h
@@ -1,18 +1,18 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef MOZZCONF_H
 #define MOZZCONF_H
 
-#if defined(XP_WIN) && defined(ZLIB_DLL)
-#undef ZLIB_DLL
+#if defined(XP_WIN)
+#define ZLIB_DLL 1
 #endif
 
 /* Exported Symbols */
 #define zlibVersion MOZ_Z_zlibVersion
 #define deflate MOZ_Z_deflate
 #define deflateEnd MOZ_Z_deflateEnd
 #define inflate MOZ_Z_inflate
 #define inflateEnd MOZ_Z_inflateEnd

--- a/mozglue/build/Makefile.in
+++ b/mozglue/build/Makefile.in
@@ -51,16 +51,18 @@ mozglue.def: mozglue.def.in
 	$(PYTHON) $(topsrcdir)/config/Preprocessor.py $(ACDEFINES) $< > $@
 
 GARBAGE += mozglue.def
 
 ifneq (,$(filter -DEFAULTLIB:mozcrt,$(MOZ_GLUE_LDFLAGS)))
 # Don't install the import library if we use mozcrt
 NO_INSTALL_IMPORT_LIBRARY = 1
 endif
+
+EXTRA_DSO_LDOPTS += $(MOZ_ZLIB_LIBS)
 endif
 
 ifeq (Android,$(OS_TARGET))
 # To properly wrap jemalloc's pthread_atfork call.
 EXTRA_DSO_LDOPTS += -Wl,--wrap=pthread_atfork
 CPPSRCS += BionicGlue.cpp
 SHARED_LIBRARY_LIBS += $(call EXPAND_LIBNAME_PATH,android,$(DEPTH)/other-licenses/android)
 endif

--- a/netwerk/streamconv/converters/Makefile.in
+++ b/netwerk/streamconv/converters/Makefile.in
@@ -46,13 +46,9 @@ endif
 FORCE_STATIC_LIB = 1
 
 LOCAL_INCLUDES =                        \
         -I$(topsrcdir)/netwerk/base/src \
         $(NULL)
 
 include $(topsrcdir)/config/rules.mk
 
-ifeq ($(OS_ARCH),WINNT)
-DEFINES		+= -DZLIB_DLL
-endif
-
 DEFINES += -DIMPL_NS_NET

--- a/toolkit/library/Makefile.in
+++ b/toolkit/library/Makefile.in
@@ -74,20 +74,16 @@ RCINCLUDE = xulrunner.rc
 ifndef MOZ_NATIVE_ZLIB
 CPPSRCS += dlldeps-zlib.cpp
 endif
 
 LOCAL_INCLUDES += -I$(topsrcdir)/widget/windows
 LOCAL_INCLUDES += -I$(topsrcdir)/xpcom/base
 endif
 
-ifneq (,$(filter WINNT OS2,$(OS_ARCH)))
-DEFINES += -DZLIB_DLL=1
-endif
-
 ifeq ($(OS_ARCH),OS2)
 
 CPPSRCS += \
   nsGFXDeps.cpp \
   $(NULL)
 
 ifndef MOZ_NATIVE_ZLIB
 CPPSRCS += dlldeps-zlib.cpp
@@ -351,17 +347,19 @@ EXTRA_DSO_LDOPTS += \
 ifdef MOZ_NATIVE_JPEG
 EXTRA_DSO_LDOPTS += $(MOZ_JPEG_LIBS)
 endif
 
 ifdef MOZ_NATIVE_PNG
 EXTRA_DSO_LDOPTS += $(MOZ_PNG_LIBS)
 endif
 
+ifneq (WINNT,$(OS_ARCH))
 EXTRA_DSO_LDOPTS += $(MOZ_ZLIB_LIBS)
+endif
 
 ifdef MOZ_NATIVE_HUNSPELL
 EXTRA_DSO_LDOPTS += $(MOZ_HUNSPELL_LIBS)
 endif
 
 ifdef MOZ_NATIVE_LIBEVENT
 EXTRA_DSO_LDOPTS += $(MOZ_LIBEVENT_LIBS)
 endif

--- a/toolkit/toolkit-tiers.mk
+++ b/toolkit/toolkit-tiers.mk
@@ -16,20 +16,16 @@ tier_platform_dirs = tools/trace-malloc/
 endif
 
 ifdef MOZ_TREE_FREETYPE
 tier_platform_staticdirs += modules/freetype2
 endif
 
 tier_platform_dirs += xpcom
 
-ifndef MOZ_NATIVE_ZLIB
-tier_platform_dirs += modules/zlib
-endif
-
 tier_platform_dirs += \
 		modules/libpref \
 		intl \
 		netwerk \
 		$(NULL)
 
 ifdef MOZ_AUTH_EXTENSION
 tier_platform_dirs += extensions/auth