diff --git a/m4/lx_check_soplex.m4 b/m4/lx_check_soplex.m4
deleted file mode 100644
--- a/m4/lx_check_soplex.m4
+++ /dev/null
@@ -1,73 +0,0 @@
-AC_DEFUN([LX_CHECK_SOPLEX],
-[
-  AC_ARG_WITH([soplex],
-AS_HELP_STRING([--with-soplex@<:@=PREFIX@:>@], [search for SOPLEX under PREFIX or under the default search paths if PREFIX is not given @<:@default@:>@])
-AS_HELP_STRING([--without-soplex], [disable checking for SOPLEX]),
-              [], [with_soplex=yes])
-
-  AC_ARG_WITH([soplex-includedir],
-AS_HELP_STRING([--with-soplex-includedir=DIR], [search for SOPLEX headers in DIR]),
-              [], [with_soplex_includedir=no])
-
-  AC_ARG_WITH([soplex-libdir],
-AS_HELP_STRING([--with-soplex-libdir=DIR], [search for SOPLEX libraries in DIR]),
-              [], [with_soplex_libdir=no])
-
-  lx_soplex_found=no
-  if test x"$with_soplex" != x"no"; then
-    AC_MSG_CHECKING([for SOPLEX])
-
-    if test x"$with_soplex_includedir" != x"no"; then
-      SOPLEX_CXXFLAGS="-I$with_soplex_includedir"
-    elif test x"$with_soplex" != x"yes"; then
-      SOPLEX_CXXFLAGS="-I$with_soplex/src"
-    fi
-
-    if test x"$with_soplex_libdir" != x"no"; then
-      SOPLEX_LDFLAGS="-L$with_soplex_libdir"
-    elif test x"$with_soplex" != x"yes"; then
-      SOPLEX_LDFLAGS="-L$with_soplex/lib"
-    fi
-    SOPLEX_LIBS="-lsoplex -lz"
-
-    lx_save_cxxflags="$CXXFLAGS"
-    lx_save_ldflags="$LDFLAGS"
-    lx_save_libs="$LIBS"
-    CXXFLAGS="$SOPLEX_CXXFLAGS"
-    LDFLAGS="$SOPLEX_LDFLAGS"
-    LIBS="$SOPLEX_LIBS"
-
-    lx_soplex_test_prog='
-      #include <soplex.h>
-
-      int main(int argc, char** argv)
-      {
-        soplex::SoPlex soplex;
-        return 0;
-      }'
-
-    AC_LANG_PUSH(C++)
-    AC_LINK_IFELSE([$lx_soplex_test_prog], [lx_soplex_found=yes], [lx_soplex_found=no])
-    AC_LANG_POP(C++)
-
-    CXXFLAGS="$lx_save_cxxflags"
-    LDFLAGS="$lx_save_ldflags"
-    LIBS="$lx_save_libs"
-
-    if test x"$lx_soplex_found" = x"yes"; then
-      AC_DEFINE([LEMON_HAVE_SOPLEX], [1], [Define to 1 if you have SOPLEX.])
-      lx_lp_found=yes
-      AC_DEFINE([LEMON_HAVE_LP], [1], [Define to 1 if you have any LP solver.])
-      AC_MSG_RESULT([yes])
-    else
-      SOPLEX_CXXFLAGS=""
-      SOPLEX_LDFLAGS=""
-      SOPLEX_LIBS=""
-      AC_MSG_RESULT([no])
-    fi
-  fi
-  SOPLEX_LIBS="$SOPLEX_LDFLAGS $SOPLEX_LIBS"
-  AC_SUBST(SOPLEX_CXXFLAGS)
-  AC_SUBST(SOPLEX_LIBS)
-  AM_CONDITIONAL([HAVE_SOPLEX], [test x"$lx_soplex_found" = x"yes"])
-])