diff -up seamonkey-2.48/mozilla/config/Makefile.in.system-harfbuzz seamonkey-2.48/mozilla/config/Makefile.in
--- seamonkey-2.48/mozilla/config/Makefile.in.system-harfbuzz	2017-08-03 00:37:03.801988205 +0200
+++ seamonkey-2.48/mozilla/config/Makefile.in	2017-08-03 00:37:05.731977160 +0200
@@ -41,6 +41,8 @@ export:: $(export-preqs)
 	$(PYTHON) -m mozbuild.action.preprocessor $(DEFINES) $(ACDEFINES) \
 		-DMOZ_TREE_CAIRO=$(MOZ_TREE_CAIRO) \
 		-DMOZ_TREE_PIXMAN=$(MOZ_TREE_PIXMAN) \
+		-DMOZ_SYSTEM_GRAPHITE2=$(MOZ_SYSTEM_GRAPHITE2) \
+		-DMOZ_SYSTEM_HARFBUZZ=$(MOZ_SYSTEM_HARFBUZZ) \
 		-DMOZ_SYSTEM_HUNSPELL=$(MOZ_SYSTEM_HUNSPELL) \
 		-DMOZ_SYSTEM_BZ2=$(MOZ_SYSTEM_BZ2) \
 		-DMOZ_SYSTEM_ZLIB=$(MOZ_SYSTEM_ZLIB) \
diff -up seamonkey-2.48/mozilla/config/system-headers.system-harfbuzz seamonkey-2.48/mozilla/config/system-headers
--- seamonkey-2.48/mozilla/config/system-headers.system-harfbuzz	2017-08-03 00:37:03.813988136 +0200
+++ seamonkey-2.48/mozilla/config/system-headers	2017-08-03 00:37:05.743977091 +0200
@@ -1265,6 +1265,15 @@ libsn/sn-launcher.h
 libsn/sn-monitor.h
 libsn/sn-util.h
 #endif
+#if MOZ_SYSTEM_GRAPHITE2==1
+graphite2/Font.h
+graphite2/Segment.h
+#endif
+#if MOZ_SYSTEM_HARFBUZZ==1
+harfbuzz/hb-glib.h
+harfbuzz/hb-ot.h
+harfbuzz/hb.h
+#endif
 #if MOZ_SYSTEM_HUNSPELL==1
 hunspell.hxx
 #endif
diff -up seamonkey-2.48/mozilla/dom/base/moz.build.system-harfbuzz seamonkey-2.48/mozilla/dom/base/moz.build
--- seamonkey-2.48/mozilla/dom/base/moz.build.system-harfbuzz	2017-07-07 07:36:00.000000000 +0200
+++ seamonkey-2.48/mozilla/dom/base/moz.build	2017-08-03 00:37:05.757977011 +0200
@@ -458,6 +458,9 @@ if CONFIG['MOZ_BUILD_APP'] in ['browser'
 if CONFIG['MOZ_X11']:
     CXXFLAGS += CONFIG['TK_CFLAGS']
 
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
+
 GENERATED_FILES += [
     'PropertyUseCounterMap.inc',
     'UseCounterList.h',
diff -up seamonkey-2.48/mozilla/gfx/graphite2/moz-gr-update.sh.system-harfbuzz seamonkey-2.48/mozilla/gfx/graphite2/moz-gr-update.sh
--- seamonkey-2.48/mozilla/gfx/graphite2/moz-gr-update.sh.system-harfbuzz	2017-07-07 07:27:00.000000000 +0200
+++ seamonkey-2.48/mozilla/gfx/graphite2/moz-gr-update.sh	2017-08-03 00:37:05.770976937 +0200
@@ -1,6 +1,7 @@
 #!/bin/bash
 
 # Script used to update the Graphite2 library in the mozilla source tree
+# and bump version for --with-system-graphite2
 
 # This script lives in gfx/graphite2, along with the library source,
 # but must be run from the top level of the mozilla-central tree.
@@ -37,12 +38,16 @@ echo "See" $0 "for update procedure." >>
 #find gfx/graphite2/ -name "*.cpp" -exec perl -p -i -e "s/<cstdio>/<stdio.h>/;s/Windows.h/windows.h/;" {} \;
 #find gfx/graphite2/ -name "*.h" -exec perl -p -i -e "s/<cstdio>/<stdio.h>/;s/Windows.h/windows.h/;" {} \;
 
+# chase version for --with-system-graphite2
+perl -p -i -e "s/[0-9]+\,[0-9]+\,[0-9]+/$RELEASE/ and tr/./,/ \
+  if /GR2_VERSION_REQUIRE/" old-configure.in
+
 # summarize what's been touched
 echo Updated to $RELEASE.
 echo Here is what changed in the gfx/graphite2 directory:
 echo
 
-hg stat gfx/graphite2
+hg stat old-configure.in gfx/graphite2
 
 echo
 echo If gfx/graphite2/src/files.mk has changed, please make corresponding
diff -up seamonkey-2.48/mozilla/gfx/harfbuzz/README-mozilla.system-harfbuzz seamonkey-2.48/mozilla/gfx/harfbuzz/README-mozilla
--- seamonkey-2.48/mozilla/gfx/harfbuzz/README-mozilla.system-harfbuzz	2017-07-07 07:36:33.000000000 +0200
+++ seamonkey-2.48/mozilla/gfx/harfbuzz/README-mozilla	2017-08-03 00:37:05.781976874 +0200
@@ -22,3 +22,8 @@ the mozilla tree.
 
 If the collection of source files changes, manual updates to moz.build may be
 needed, as we don't use the upstream makefiles.
+
+The in-tree copy may be omitted during build by --with-system-harfbuzz.
+Make sure to keep pkg-config version check within toolkit/moz.configure in sync
+with checkout version or increment latest tag by one if it's not based
+on upstream release.
diff -up seamonkey-2.48/mozilla/gfx/moz.build.system-harfbuzz seamonkey-2.48/mozilla/gfx/moz.build
--- seamonkey-2.48/mozilla/gfx/moz.build.system-harfbuzz	2017-07-07 07:36:34.000000000 +0200
+++ seamonkey-2.48/mozilla/gfx/moz.build	2017-08-03 00:37:05.791976816 +0200
@@ -7,6 +7,12 @@
 if CONFIG['MOZ_TREE_CAIRO']:
     DIRS += ['cairo']
 
+if not CONFIG['MOZ_SYSTEM_GRAPHITE2']:
+    DIRS += ['graphite2/src' ]
+
+if not CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    DIRS += ['harfbuzz/src']
+
 DIRS += [
     '2d',
     'ycbcr',
@@ -15,8 +21,6 @@ DIRS += [
     'qcms',
     'gl',
     'layers',
-    'graphite2/src',
-    'harfbuzz/src',
     'ots/src',
     'thebes',
     'ipc',
diff -up seamonkey-2.48/mozilla/gfx/skia/generate_mozbuild.py.system-harfbuzz seamonkey-2.48/mozilla/gfx/skia/generate_mozbuild.py
--- seamonkey-2.48/mozilla/gfx/skia/generate_mozbuild.py.system-harfbuzz	2017-08-03 00:37:05.805976736 +0200
+++ seamonkey-2.48/mozilla/gfx/skia/generate_mozbuild.py	2017-08-03 00:45:15.924133674 +0200
@@ -140,6 +140,9 @@
         '-Wno-unused-private-field',
     ]
 
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
+
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk2', 'gtk3', 'android'):
     CXXFLAGS += CONFIG['MOZ_CAIRO_CFLAGS']
     CXXFLAGS += CONFIG['CAIRO_FT_CFLAGS']
diff -up seamonkey-2.48/mozilla/gfx/skia/moz.build.system-harfbuzz seamonkey-2.48/mozilla/gfx/skia/moz.build
--- seamonkey-2.48/mozilla/gfx/skia/moz.build.system-harfbuzz	2017-08-03 00:37:06.073975203 +0200
+++ seamonkey-2.48/mozilla/gfx/skia/moz.build	2017-08-03 00:45:57.021895127 +0200
@@ -750,6 +750,9 @@
         '-Wno-unused-private-field',
     ]
 
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
+
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk2', 'gtk3', 'android'):
     CXXFLAGS += CONFIG['MOZ_CAIRO_CFLAGS']
     CXXFLAGS += CONFIG['CAIRO_FT_CFLAGS']
diff -up seamonkey-2.48/mozilla/gfx/thebes/moz.build.system-harfbuzz seamonkey-2.48/mozilla/gfx/thebes/moz.build
--- seamonkey-2.48/mozilla/gfx/thebes/moz.build.system-harfbuzz	2017-08-03 00:37:06.093975088 +0200
+++ seamonkey-2.48/mozilla/gfx/thebes/moz.build	2017-08-03 00:46:25.921727371 +0200
@@ -286,7 +286,13 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk
 LOCAL_INCLUDES += CONFIG['SKIA_INCLUDES']
 LOCAL_INCLUDES += ['/media/libyuv/include']
 
-DEFINES['GRAPHITE2_STATIC'] = True
+if CONFIG['MOZ_SYSTEM_GRAPHITE2']:
+    CXXFLAGS += CONFIG['MOZ_GRAPHITE2_CFLAGS']
+else:
+    DEFINES['GRAPHITE2_STATIC'] = True
+
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
 
 if CONFIG['CLANG_CXX']:
     # Suppress warnings from Skia header files.
diff -up seamonkey-2.48/mozilla/intl/unicharutil/util/moz.build.system-harfbuzz seamonkey-2.48/mozilla/intl/unicharutil/util/moz.build
--- seamonkey-2.48/mozilla/intl/unicharutil/util/moz.build.system-harfbuzz	2017-08-03 00:37:06.114974968 +0200
+++ seamonkey-2.48/mozilla/intl/unicharutil/util/moz.build	2017-08-03 00:47:02.948512428 +0200
@@ -42,4 +42,7 @@ if CONFIG['_MSC_VER']:
 if CONFIG['ENABLE_INTL_API']:
     USE_LIBS += ['icu']
 
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
+
 DIST_INSTALL = True
diff -up seamonkey-2.48/mozilla/netwerk/dns/moz.build.system-harfbuzz seamonkey-2.48/mozilla/netwerk/dns/moz.build
--- seamonkey-2.48/mozilla/netwerk/dns/moz.build.system-harfbuzz	2017-08-03 00:37:06.133974859 +0200
+++ seamonkey-2.48/mozilla/netwerk/dns/moz.build	2017-08-03 00:47:53.877216760 +0200
@@ -66,6 +66,9 @@ LOCAL_INCLUDES += [
     '/netwerk/base',
 ]
 
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    CXXFLAGS += CONFIG['MOZ_HARFBUZZ_CFLAGS']
+
 if CONFIG['ENABLE_INTL_API']:
     DEFINES['IDNA2008'] = True
     USE_LIBS += ['icu']
diff -up seamonkey-2.48/mozilla/old-configure.in.system-harfbuzz seamonkey-2.48/mozilla/old-configure.in
--- seamonkey-2.48/mozilla/old-configure.in.system-harfbuzz	2017-08-03 00:37:05.711977274 +0200
+++ seamonkey-2.48/mozilla/old-configure.in	2017-08-03 00:37:06.165974676 +0200
@@ -5280,6 +5280,27 @@ if test "$USE_FC_FREETYPE"; then
 fi
 
 dnl ========================================================
+dnl Check for graphite2
+dnl ========================================================
+if test -n "$MOZ_SYSTEM_GRAPHITE2"; then
+    dnl graphite2.pc has bogus version, check manually
+    _SAVE_CFLAGS=$CFLAGS
+    CFLAGS="$CFLAGS $MOZ_GRAPHITE2_CFLAGS"
+    AC_TRY_COMPILE([ #include <graphite2/Font.h>
+                     #define GR2_VERSION_REQUIRE(major,minor,bugfix)  \
+                             ( GR2_VERSION_MAJOR * 10000 + GR2_VERSION_MINOR \
+                               * 100 + GR2_VERSION_BUGFIX >= \
+                               (major) * 10000 + (minor) * 100 + (bugfix) )
+                   ], [
+                     #if !GR2_VERSION_REQUIRE(1,3,8)
+                     #error "Insufficient graphite2 version."
+                     #endif
+                   ], [],
+                   [AC_MSG_ERROR([--with-system-graphite2 requested but no working libgraphite2 found])])
+    CFLAGS=$_SAVE_CFLAGS
+fi
+
+dnl ========================================================
 dnl Check for pixman and cairo
 dnl ========================================================
 
diff -up seamonkey-2.48/mozilla/toolkit/library/moz.build.system-harfbuzz seamonkey-2.48/mozilla/toolkit/library/moz.build
--- seamonkey-2.48/mozilla/toolkit/library/moz.build.system-harfbuzz	2017-08-03 00:37:03.848987936 +0200
+++ seamonkey-2.48/mozilla/toolkit/library/moz.build	2017-08-03 00:37:06.183974573 +0200
@@ -234,6 +234,12 @@ if CONFIG['MOZ_SYSTEM_JPEG']:
 if CONFIG['MOZ_SYSTEM_PNG']:
     OS_LIBS += CONFIG['MOZ_PNG_LIBS']
 
+if CONFIG['MOZ_SYSTEM_GRAPHITE2']:
+    OS_LIBS += CONFIG['MOZ_GRAPHITE2_LIBS']
+
+if CONFIG['MOZ_SYSTEM_HARFBUZZ']:
+    OS_LIBS += CONFIG['MOZ_HARFBUZZ_LIBS']
+
 if CONFIG['MOZ_SYSTEM_HUNSPELL']:
     OS_LIBS += CONFIG['MOZ_HUNSPELL_LIBS']
 
diff -up seamonkey-2.48/mozilla/toolkit/moz.configure.system-harfbuzz seamonkey-2.48/mozilla/toolkit/moz.configure
--- seamonkey-2.48/mozilla/toolkit/moz.configure.system-harfbuzz	2017-07-07 07:38:26.000000000 +0200
+++ seamonkey-2.48/mozilla/toolkit/moz.configure	2017-08-03 00:37:06.195974504 +0200
@@ -338,6 +338,34 @@
 add_old_configure_assignment('FT2_CFLAGS',
                              delayed_getattr(ft2_info, 'cflags'))
 
+# Graphite2
+# ==============================================================
+option('--with-system-graphite2',
+       help="Use system graphite2 (located with pkgconfig)")
+
+@depends('--with-system-graphite2')
+def check_for_graphite2(value):
+    return bool(value)
+
+system_graphite2 = pkg_check_modules('MOZ_GRAPHITE2', 'graphite2',
+                                     when=check_for_graphite2)
+
+set_config('MOZ_SYSTEM_GRAPHITE2', depends_if(system_graphite2)(lambda _: True))
+
+# HarfBuzz
+# ==============================================================
+option('--with-system-harfbuzz',
+       help="Use system harfbuzz (located with pkgconfig)")
+
+@depends('--with-system-harfbuzz')
+def check_for_harfbuzz(value):
+    return bool(value)
+
+system_harfbuzz = pkg_check_modules('MOZ_HARFBUZZ', 'harfbuzz >= 1.3.3',
+                                    when=check_for_harfbuzz)
+
+set_config('MOZ_SYSTEM_HARFBUZZ', depends_if(system_harfbuzz)(lambda _: True))
+
 # Apple platform decoder support
 # ==============================================================
 @depends(toolkit)