diff --git a/config/Makefile.in b/config/Makefile.in
--- config/Makefile.in
+++ config/Makefile.in
@@ -97,16 +97,17 @@ export:: $(export-preqs)
 		-DMOZ_TREE_PIXMAN=$(MOZ_TREE_PIXMAN) \
 		-DMOZ_NATIVE_HUNSPELL=$(MOZ_NATIVE_HUNSPELL) \
 		-DMOZ_NATIVE_BZ2=$(MOZ_NATIVE_BZ2) \
 		-DMOZ_NATIVE_ZLIB=$(MOZ_NATIVE_ZLIB) \
 		-DMOZ_NATIVE_PNG=$(MOZ_NATIVE_PNG) \
 		-DMOZ_NATIVE_JPEG=$(MOZ_NATIVE_JPEG) \
 		-DMOZ_NATIVE_LIBEVENT=$(MOZ_NATIVE_LIBEVENT) \
 		-DMOZ_NATIVE_LIBVPX=$(MOZ_NATIVE_LIBVPX) \
+		-DMOZ_NATIVE_ICU=$(MOZ_NATIVE_ICU) \
 		$(srcdir)/system-headers | $(PERL) $(topsrcdir)/nsprpub/config/make-system-wrappers.pl system_wrappers
 	$(INSTALL) system_wrappers $(DIST)
 
 GARBAGE_DIRS += system_wrappers
 endif
 
 ifdef WRAP_STL_INCLUDES
 ifdef GNU_CXX
diff --git a/config/system-headers b/config/system-headers
--- config/system-headers
+++ config/system-headers
@@ -1125,8 +1125,19 @@ gst/video/video.h
 sys/msg.h
 sys/ipc.h
 sys/thr.h
 sys/user.h
 kvm.h
 spawn.h
 err.h
 xlocale.h
+#if MOZ_NATIVE_ICU==1
+unicode/locid.h
+unicode/numsys.h
+unicode/ucal.h
+unicode/ucol.h
+unicode/udat.h
+unicode/udatpg.h
+unicode/uenum.h
+unicode/unum.h
+unicode/ustring.h
+#endif
diff --git a/configure.in b/configure.in
--- configure.in
+++ configure.in
@@ -4134,16 +4134,32 @@ if test -n "$MOZ_NATIVE_FFI"; then
         PKG_CHECK_MODULES(MOZ_FFI, libffi > 3.0.9)
     else
         PKG_CHECK_MODULES(MOZ_FFI, libffi >= 3.0.9)
     fi
     MOZ_JS_STATIC_LIBS="$MOZ_JS_STATIC_LIBS $MOZ_FFI_LIBS"
 fi
 
 dnl ========================================================
+dnl system icu support
+dnl ========================================================
+MOZ_NATIVE_ICU=
+MOZ_ARG_WITH_BOOL(system-icu,
+[  --with-system-icu
+                          Use system icu (located with pkgconfig)],
+    MOZ_NATIVE_ICU=1)
+
+if test -n "$MOZ_NATIVE_ICU"; then
+    PKG_CHECK_MODULES(MOZ_ICU, icu-i18n >= 50.1)
+    MOZ_JS_STATIC_LIBS="$MOZ_JS_STATIC_LIBS $MOZ_ICU_LIBS"
+fi
+
+AC_SUBST(MOZ_NATIVE_ICU)
+
+dnl ========================================================
 dnl Java SDK support
 dnl ========================================================
 
 JAVA_BIN_PATH=
 MOZ_ARG_WITH_STRING(java-bin-path,
 [  --with-java-bin-path=dir
                           Location of Java binaries (java, javac, jar)],
     JAVA_BIN_PATH=$withval)
diff --git a/js/src/Makefile.in b/js/src/Makefile.in
--- js/src/Makefile.in.orig	2013-10-22 08:19:02.000000000 +0200
+++ js/src/Makefile.in	2013-10-29 10:11:58.272605098 +0100
@@ -237,10 +237,14 @@
 # ICU headers need to be available whether we build with the complete
 # Internationalization API or not - ICU stubs rely on them.
 
+ifdef MOZ_NATIVE_ICU
+LOCAL_INCLUDES += $(MOZ_ICU_CFLAGS)
+else
 LOCAL_INCLUDES += \
   -I$(topsrcdir)/../../intl/icu/source/common \
   -I$(topsrcdir)/../../intl/icu/source/i18n \
   $(NULL)
+endif
 
 ifdef ENABLE_INTL_API
 
@@ -260,6 +264,7 @@
 ICU_MAKE = $(MAKE)
 endif
 
+ifndef MOZ_NATIVE_ICU
 # - Build ICU as part of the "export" target, so things get built
 #   in the right order.
 # - ICU requires GNU make according to its readme.html. pymake can't be used
@@ -276,6 +281,7 @@
 	$(call SUBMAKE,$@,intl/icu)
 
 endif
+endif
 
 #
 # END ECMAScript Internationalization API
@@ -413,7 +419,11 @@
 DEFINES += -DUSE_ZLIB
 endif
 
-SHARED_LIBRARY_LIBS += $(ICU_LIBS)
+ifdef MOZ_NATIVE_ICU
+EXTRA_DSO_LDOPTS += $(MOZ_ICU_LIBS)
+else
+SHARED_LIBRARY_LIBS += $(MOZ_ICU_LIBS)
+endif
 
 # Prevent floating point errors caused by VC++ optimizations
 ifdef _MSC_VER
diff --git a/js/src/config/Makefile.in b/js/src/config/Makefile.in
--- js/src/config/Makefile.in
+++ js/src/config/Makefile.in
@@ -54,16 +54,17 @@ include $(topsrcdir)/config/rules.mk
 
 HOST_CFLAGS += -DUNICODE -D_UNICODE
 
 ifdef WRAP_SYSTEM_INCLUDES
 export:: \
   $(call mkdir_deps,system_wrappers_js) \
   $(NULL)
 	$(PYTHON) $(srcdir)/Preprocessor.py $(DEFINES) $(ACDEFINES) \
+		-DMOZ_NATIVE_ICU=$(MOZ_NATIVE_ICU) \
 		$(srcdir)/system-headers | $(PERL) $(srcdir)/make-system-wrappers.pl system_wrappers_js
 	$(INSTALL) system_wrappers_js $(DIST)
 
 GARBAGE_DIRS += system_wrappers_js
 endif
 
 GARBAGE += $(srcdir)/*.pyc *.pyc
 
diff --git a/js/src/config/system-headers b/js/src/config/system-headers
--- js/src/config/system-headers
+++ js/src/config/system-headers
@@ -1125,8 +1125,19 @@ gst/video/video.h
 sys/msg.h
 sys/ipc.h
 sys/thr.h
 sys/user.h
 kvm.h
 spawn.h
 err.h
 xlocale.h
+#if MOZ_NATIVE_ICU==1
+unicode/locid.h
+unicode/numsys.h
+unicode/ucal.h
+unicode/ucol.h
+unicode/udat.h
+unicode/udatpg.h
+unicode/uenum.h
+unicode/unum.h
+unicode/ustring.h
+#endif
diff --git a/js/src/configure.in b/js/src/configure.in
--- js/src/configure.in
+++ js/src/configure.in
@@ -4406,59 +4406,68 @@ if test "$ACCESSIBILITY" -a "$MOZ_ENABLE
     AC_DEFINE_UNQUOTED(ATK_MINOR_VERSION, $ATK_MINOR_VERSION)
     AC_DEFINE_UNQUOTED(ATK_REV_VERSION, $ATK_REV_VERSION)
 fi
 
 
 dnl ========================================================
 dnl ECMAScript Internationalization API Support (uses ICU)
 dnl ========================================================
+ICU_LIB_NAMES=
+MOZ_NATIVE_ICU=
+MOZ_ARG_WITH_BOOL(system-icu,
+[  --with-system-icu
+                          Use system icu (located with pkgconfig)],
+    MOZ_NATIVE_ICU=1)
+
+if test -n "$MOZ_NATIVE_ICU"; then
+    PKG_CHECK_MODULES(MOZ_ICU, icu-i18n >= 50.1)
+fi
 
 if test -n "$JS_STANDALONE"; then
     ENABLE_INTL_API=1
 fi
 MOZ_ARG_ENABLE_BOOL(intl-api,
 [  --enable-intl-api       Enable ECMAScript Internationalization API (default=yes for standalone JS)],
     ENABLE_INTL_API=1,
     ENABLE_INTL_API= )
 
 dnl Settings for the implementation of the ECMAScript Internationalization API
 if test -n "$ENABLE_INTL_API"; then
     AC_DEFINE(ENABLE_INTL_API)
-    # We build ICU as a static library.
-    AC_DEFINE(U_STATIC_IMPLEMENTATION)
-
-    case "$OS_TARGET" in
-        WINNT)
-            ICU_LIB_NAMES="icuin icuuc icudt"
-            ;;
-        Darwin|Linux)
-            ICU_LIB_NAMES="icui18n icuuc icudata"
-            ;;
-        *)
-            AC_MSG_ERROR([ECMAScript Internationalization API is not yet supported on this platform])
-    esac
-
-    ICU_LIBS='$(call EXPAND_LIBNAME_PATH,$(ICU_LIB_NAMES),$(DEPTH)/intl/icu/lib)'
-else
-    ICU_LIB_NAMES=
-    ICU_LIBS=
+
+    if test -z "$MOZ_NATIVE_ICU"; then
+        case "$OS_TARGET" in
+            WINNT)
+                ICU_LIB_NAMES="icuin icuuc icudt"
+                ;;
+            Darwin|Linux)
+                ICU_LIB_NAMES="icui18n icuuc icudata"
+                ;;
+            *)
+                AC_MSG_ERROR([ECMAScript Internationalization API is not yet supported on this platform])
+        esac
+        MOZ_ICU_LIBS='$(call EXPAND_LIBNAME_PATH,$(ICU_LIB_NAMES),$(DEPTH)/intl/icu/lib)'
+    fi
 fi
 
 AC_SUBST(ENABLE_INTL_API)
 AC_SUBST(ICU_LIB_NAMES)
-AC_SUBST(ICU_LIBS)
-
-dnl Source files that use ICU should have control over which parts of the ICU
-dnl namespace they want to use.
-AC_DEFINE(U_USING_ICU_NAMESPACE,0)
-
+AC_SUBST(MOZ_ICU_LIBS)
+AC_SUBST(MOZ_NATIVE_ICU)
 
 dnl Settings for ICU
-if test -n "$ENABLE_INTL_API" ; then
+if test -n "$ENABLE_INTL_API" -a -z "$MOZ_NATIVE_ICU"; then
+    dnl We build ICU as a static library.
+    AC_DEFINE(U_STATIC_IMPLEMENTATION)
+
+    dnl Source files that use ICU should have control over which parts of the ICU
+    dnl namespace they want to use.
+    AC_DEFINE(U_USING_ICU_NAMESPACE,0)
+
     # Set ICU compile options
     ICU_CPPFLAGS=""
     # don't use icu namespace automatically in client code
     ICU_CPPFLAGS="$ICU_CPPFLAGS -DU_USING_ICU_NAMESPACE=0"
     # don't include obsolete header files
     ICU_CPPFLAGS="$ICU_CPPFLAGS -DU_NO_DEFAULT_INCLUDE_UTF_HEADERS=1"
     # remove chunks of the library that we don't need (yet)
     ICU_CPPFLAGS="$ICU_CPPFLAGS -DUCONFIG_NO_LEGACY_CONVERSION"
diff --git a/js/src/gdb/Makefile.in b/js/src/gdb/Makefile.in
--- js/src/gdb/Makefile.in
+++ js/src/gdb/Makefile.in
@@ -14,16 +14,20 @@ include $(DEPTH)/config/autoconf.mk
 # Building against js_static requires that we declare mfbt sybols "exported"
 # on its behalf.
 DEFINES += -DEXPORT_JS_API -DIMPL_MFBT
 
 LIBS = $(DEPTH)/$(LIB_PREFIX)js_static.$(LIB_SUFFIX) $(NSPR_LIBS) $(MOZ_ZLIB_LIBS)
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
+ifdef MOZ_NATIVE_ICU
+EXTRA_LIBS += $(MOZ_ICU_LIBS)
+endif
+
 EXTRA_LIBS += $(MOZ_FFI_LIBS)
 
 # Place a GDB Python auto-load file next to the gdb-tests executable, both
 # in the build directory and in the dist/bin directory.
 PP_TARGETS += GDB_AUTOLOAD
 GDB_AUTOLOAD := gdb-tests-gdb.py.in
 GDB_AUTOLOAD_FLAGS := -Dtopsrcdir=$(abspath $(topsrcdir))
 
diff --git a/js/src/jsapi-tests/Makefile.in b/js/src/jsapi-tests/Makefile.in
--- js/src/jsapi-tests/Makefile.in
+++ js/src/jsapi-tests/Makefile.in
@@ -15,16 +15,20 @@ 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) $(MOZ_ZLIB_LIBS)
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
+ifdef MOZ_NATIVE_ICU
+EXTRA_LIBS += $(MOZ_ICU_LIBS)
+endif
+
 EXTRA_LIBS += $(MOZ_FFI_LIBS)
 
 ifdef QEMU_EXE
 MOZ_POST_PROGRAM_COMMAND = $(topsrcdir)/build/qemu-wrap --qemu $(QEMU_EXE) --libdir $(CROSS_LIB)
 endif
 
 # Place a GDB Python auto-load file next to the jsapi-tests executable in
 # the build directory.
diff --git a/js/src/shell/Makefile.in b/js/src/shell/Makefile.in
--- js/src/shell/Makefile.in
+++ js/src/shell/Makefile.in
@@ -22,16 +22,19 @@ 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) $(MOZ_ZLIB_LIBS)
 ifdef MOZ_NATIVE_FFI
 EXTRA_LIBS += $(MOZ_FFI_LIBS)
 endif
+ifdef MOZ_NATIVE_ICU
+EXTRA_LIBS += $(MOZ_ICU_LIBS)
+endif
 
 LOCAL_INCLUDES += -I$(topsrcdir) -I..
 
 ifeq ($(OS_ARCH),Darwin)
 ifeq ($(TARGET_CPU),x86_64)
 DARWIN_EXE_LDFLAGS += -pagezero_size 10000 -image_base 100000000
 endif
 endif