diff -up R-3.0.2/configure.ac.system-tre R-3.0.2/configure.ac
--- R-3.0.2/configure.ac.system-tre	2014-02-04 18:14:04.233778538 -0500
+++ R-3.0.2/configure.ac	2014-02-04 18:14:52.635733566 -0500
@@ -420,6 +420,10 @@ AC_ARG_WITH([system-pcre],
 [AS_HELP_STRING([--with-system-pcre],[use system PCRE library (if available) @<:@no@:>@])],
 [R_ARG_USE_SYSTEM(pcre)],
 [use_system_pcre=no])
+AC_ARG_WITH([system-tre],
+[AS_HELP_STRING([--with-system-tre],[use system tre library (if available) @<:@no@:>@])],
+[R_ARG_USE_SYSTEM(tre)],
+[use_system_tre=no])
 AC_ARG_WITH([system-xz],
 [AS_HELP_STRING([--with-system-xz],[use system xz (lzma) library (if available) @<:@yes@:>@])],
 [R_ARG_USE_SYSTEM(xz)],
@@ -2221,6 +2225,9 @@ R_LZMA
 ## PCRE headers and libraries.
 R_PCRE
 
+## tre headers and libraries.
+R_TRE
+
 ## POSIX times.
 R_SYS_POSIX_LEAPSECONDS
 
diff -up R-3.0.2/m4/R.m4.system-tre R-3.0.2/m4/R.m4
--- R-3.0.2/m4/R.m4.system-tre	2014-02-04 18:15:08.196719109 -0500
+++ R-3.0.2/m4/R.m4	2014-02-04 18:27:32.854028384 -0500
@@ -3150,6 +3150,26 @@ fi
 AM_CONDITIONAL(BUILD_BZLIB, [test "x${have_bzlib}" = xno])
 ])# R_BZLIB
 
+## R_TRE
+## -------
+## Try finding tre library and headers.
+## We check that both are installed,
+AC_DEFUN([R_TRE],
+[if test "x${use_system_tre}" = xyes; then
+  AC_CHECK_LIB(tre, tre_regncompb, [have_tre=yes], [have_tre=no])
+  if test "${have_tre}" = yes; then
+    AC_CHECK_HEADERS(tre/tre.h, [have_tre=yes], [have_tre=no])
+  fi
+if test "x${have_tre}" = xyes; then
+  AC_DEFINE(HAVE_TRE, 1, [Define if your system has tre.])
+  LIBS="-ltre ${LIBS}"
+fi
+else
+  have_tre="no"
+fi
+AM_CONDITIONAL(BUILD_TRE, [test x${have_tre} != xyes])
+])# R_TRE
+
 ## R_LZMA
 ## -------
 ## Try finding liblzma library and headers.
diff -up R-3.0.2/src/extra/Makefile.in.system-tre R-3.0.2/src/extra/Makefile.in
--- R-3.0.2/src/extra/Makefile.in.system-tre	2014-02-04 18:31:50.263790068 -0500
+++ R-3.0.2/src/extra/Makefile.in	2014-02-04 18:32:11.792770146 -0500
@@ -22,7 +22,7 @@ LIBPCRE =@BUILD_PCRE_TRUE@ make.pcre
 LIBZ =@BUILD_ZLIB_TRUE@ make.zlib
 LIBXDR =@BUILD_XDR_TRUE@ make.xdr
 LIBINTL =@BUILD_LIBINTL_TRUE@ make.intl
-LIBTRE = make.tre
+LIBTRE =@BUILD_TRE_TRUE@ make.tre
 LIBXZ =@BUILD_XZ_TRUE@ make.xz
 EXTRAS = $(RBLAS) $(LIBBZ2) $(LIBPCRE) $(LIBZ) $(LIBXDR) $(LIBINTL) $(LIBTRE) $(LIBXZ)
 
diff -up R-3.0.2/src/extra/tre/Makefile.in.system-tre R-3.0.2/src/extra/tre/Makefile.in
--- R-3.0.2/src/extra/tre/Makefile.in.system-tre	2014-02-04 18:29:54.812896929 -0500
+++ R-3.0.2/src/extra/tre/Makefile.in	2014-02-04 18:31:15.046822660 -0500
@@ -33,7 +33,7 @@ libtre_a_SOURCES = $(SOURCES)
 libtre_a_OBJECTS = $(OBJECTS)
 
 
-all: R
+all: @BUILD_TRE_TRUE@ R
 
 Makefile: $(srcdir)/Makefile.in \
   $(top_builddir)/config.status \
@@ -44,9 +44,9 @@ Makedeps: Makefile $(DEPENDS)
 	@cat $(DEPENDS) >> Makefile
 	@touch $@
 
-R: Makefile
-	@$(MAKE) Makedeps
-	@$(MAKE) $(noinst_LIBRARIES)
+R: Makefile @BUILD_TRE_TRUE@
+	@BUILD_TRE_TRUE@ @$(MAKE) Makedeps
+	@BUILD_TRE_TRUE@ @$(MAKE) $(noinst_LIBRARIES)
 
 libtre.a: $(libtre_a_OBJECTS)
 	rm -f $@
diff -up R-3.0.2/src/main/Makefile.in.system-tre R-3.0.2/src/main/Makefile.in
--- R-3.0.2/src/main/Makefile.in.system-tre	2014-02-04 18:28:02.924000533 -0500
+++ R-3.0.2/src/main/Makefile.in	2014-02-04 18:29:06.677941495 -0500
@@ -69,7 +69,7 @@ DISTFILES = Makefile.in Makefile.win \
 ZLIB_CPPFLAGS = @BUILD_ZLIB_TRUE@ -I$(top_srcdir)/src/extra/zlib
 BZLIB_CPPFLAGS = @BUILD_BZLIB_TRUE@ -I$(top_srcdir)/src/extra/bzip2
 PCRE_CPPFLAGS = @BUILD_PCRE_TRUE@ -I$(top_srcdir)/src/extra/pcre
-TRE_CPPFLAGS = -I$(top_srcdir)/src/extra
+TRE_CPPFLAGS = @BUILD_TRE_TRUE@ -I$(top_srcdir)/src/extra
 XDR_CPPFLAGS = @BUILD_XDR_TRUE@ -I$(top_srcdir)/src/extra/xdr
 @BUILD_XDR_FALSE@XDR_CPPFLAGS = @TIRPC_CPPFLAGS@
 XZ_CPPFLAGS = @BUILD_XZ_TRUE@  -I$(top_srcdir)/src/extra/xz/api
@@ -84,7 +84,7 @@ ALL_CPPFLAGS = $(ZLIB_CPPFLAGS) $(BZLIB_
 R_ZLIBS = @BUILD_ZLIB_TRUE@ ../extra/zlib/libz.a
 R_BZLIBS = @BUILD_BZLIB_TRUE@ ../extra/bzip2/libbz2.a
 R_PCRE = @BUILD_PCRE_TRUE@ ../extra/pcre/libpcre.a
-R_TRE = ../extra/tre/libtre.a
+R_TRE = @BUILD_TRE_TRUE@ ../extra/tre/libtre.a
 R_XDR = @BUILD_XDR_TRUE@ ../extra/xdr/libxdr.a
 R_XZ = @BUILD_XZ_TRUE@  ../extra/xz/liblzma.a
 R_LIBINTL = @BUILD_LIBINTL_TRUE@ ../extra/intl/libintl.a