diff --git a/aclocal/ax_dmd.m4 b/aclocal/ax_dmd.m4
new file mode 100644
index 0000000..13b84b0
--- /dev/null
+++ b/aclocal/ax_dmd.m4
@@ -0,0 +1,107 @@
+dnl @synopsis AX_DMD
+dnl
+dnl Test for the presence of a DMD-compatible D2 compiler, and (optionally)
+dnl specified modules on the import path.
+dnl
+dnl If "DMD" is defined in the environment, that will be the only
+dnl dmd command tested. Otherwise, a hard-coded list will be used.
+dnl
+dnl After AX_DMD runs, the shell variables "success" and "ax_dmd" are set to
+dnl "yes" or "no", and "DMD" is set to the appropriate command. Furthermore,
+dnl "dmd_optlink" will be set to "yes" or "no" depending on whether OPTLINK is
+dnl used as the linker (DMD/Windows), and "dmd_of_dirsep" will be set to the
+dnl directory separator to use when passing -of to DMD (OPTLINK requires a
+dnl backslash).
+dnl
+dnl AX_CHECK_D_MODULE must be run after AX_DMD. It tests for the presence of a
+dnl module in the import path of the chosen compiler, and sets the shell
+dnl variable "success" to "yes" or "no".
+dnl
+dnl @category D
+dnl @version 2011-05-31
+dnl @license AllPermissive
+dnl
+dnl Copyright (C) 2009 David Reiss
+dnl Copyright (C) 2011 David Nadlinger
+dnl Copying and distribution of this file, with or without modification,
+dnl are permitted in any medium without royalty provided the copyright
+dnl notice and this notice are preserved.
+
+
+AC_DEFUN([AX_DMD],
+         [
+          dnl Hard-coded default commands to test.
+          DMD_PROGS="dmd,gdmd,ldmd"
+
+          dnl Allow the user to specify an alternative.
+          if test -n "$DMD" ; then
+            DMD_PROGS="$DMD"
+          fi
+
+          AC_MSG_CHECKING(for DMD)
+
+          # std.algorithm as a quick way to check for D2/Phobos.
+          echo "import std.algorithm; void main() {}" > configtest_ax_dmd.d
+          success=no
+          oIFS="$IFS"
+
+          IFS=","
+          for DMD in $DMD_PROGS ; do
+            IFS="$oIFS"
+
+            echo "Running \"$DMD configtest_ax_dmd.d\"" >&AS_MESSAGE_LOG_FD
+            if $DMD configtest_ax_dmd.d >&AS_MESSAGE_LOG_FD 2>&1 ; then
+              success=yes
+              break
+            fi
+          done
+
+          if test "$success" != "yes" ; then
+            AC_MSG_RESULT(no)
+            DMD=""
+          else
+            AC_MSG_RESULT(yes)
+          fi
+
+          ax_dmd="$success"
+
+          # Test whether OPTLINK is used by trying if DMD accepts -L/? without
+          # erroring out.
+          if test "$success" == "yes" ; then
+            AC_MSG_CHECKING(whether DMD uses OPTLINK)
+            echo "Running \”$DMD -L/? configtest_ax_dmd.d\"" >&AS_MESSAGE_LOG_FD
+            if $DMD -L/? configtest_ax_dmd.d >&AS_MESSAGE_LOG_FD 2>&1 ; then
+              AC_MSG_RESULT(yes)
+              dmd_optlink="yes"
+
+              # This actually produces double slashes in the final configure
+              # output, but at least it works.
+              dmd_of_dirsep="\\\\"
+            else
+              AC_MSG_RESULT(no)
+              dmd_optlink="no"
+              dmd_of_dirsep="/"
+            fi
+          fi
+
+          rm -f configtest_ax_dmd*
+         ])
+
+
+AC_DEFUN([AX_CHECK_D_MODULE],
+         [
+          AC_MSG_CHECKING(for D module [$1])
+
+          echo "import $1; void main() {}" > configtest_ax_dmd.d
+
+          echo "Running \"$DMD configtest_ax_dmd.d\"" >&AS_MESSAGE_LOG_FD
+          if $DMD -c configtest_ax_dmd.d >&AS_MESSAGE_LOG_FD 2>&1 ; then
+            AC_MSG_RESULT(yes)
+            success=yes
+          else
+            AC_MSG_RESULT(no)
+            success=no
+          fi
+
+          rm -f configtest_ax_dmd*
+         ])