--- a/xulrunner/installer/Makefile.in
+++ b/xulrunner/installer/Makefile.in
@@ -80,16 +80,18 @@ install:: $(MOZILLA_VERSION).system.conf
 	$(SYSINSTALL) $^ $(DESTDIR)$(regdir)
 endif
 
 # Add pkg-config files to the install:: target
 
 pkg_config_files = \
 	libxul.pc \
 	libxul-embedding.pc \
+	libxul-unstable.pc \
+	libxul-embedding-unstable.pc \
 	mozilla-js.pc \
 	mozilla-plugin.pc \
 	$(NULL)
 
 ifdef MOZ_NATIVE_NSPR
 NSPR_NAME=nspr
 NSPR_VERSION=$(shell $(NSPR_CONFIG) --version)
 else

new file mode 100644
--- /dev/null
+++ b/xulrunner/installer/libxul-embedding-unstable.pc.in
@@ -0,0 +1,11 @@
+prefix=%prefix%
+sdkdir=%sdkdir%
+includedir=%includedir%
+idldir=%idldir%
+includetype=unstable
+
+Name: libxul-embedding-unstable
+Description: Static library for version-independent embedding of the Mozilla runtime (unstable API)
+Version: %MOZILLA_VERSION%
+Libs: -L${sdkdir}/lib -lxpcomglue
+Cflags: -DXPCOM_GLUE -I${includedir}/${includetype} -fshort-wchar

new file mode 100644
--- /dev/null
+++ b/xulrunner/installer/libxul-unstable.pc.in
@@ -0,0 +1,12 @@
+prefix=%prefix%
+sdkdir=%sdkdir%
+includedir=%includedir%
+idldir=%idldir%
+includetype=unstable
+
+Name: libxul
+Description: The Mozilla Runtime and Embedding Engine (unstable API)
+Version: %MOZILLA_VERSION%
+Requires: %NSPR_NAME% >= %NSPR_VERSION%
+Libs: -L${sdkdir}/lib -lxpcomglue_s -lxul -lxpcom
+Cflags: -I${includedir}/${includetype} -fshort-wchar