diff --git a/unix/depend.mk b/unix/depend.mk
new file mode 100644
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--- /dev/null
+++ b/unix/depend.mk
@@ -0,0 +1,76 @@
+#
+# C / C++ header dependency stuff
+#
+# Needs GNU make and vncmkdepend, a hacked version of makedepend
+
+.SUFFIXES: .d
+
+CMAKEDEPEND = vncmkdepend
+CXXMAKEDEPEND = vncmkdepend
+
+#
+# The recommended method of doing dependency analysis in the GNU make manual
+# turns out to be painfully slow.  This method is similar but it's
+# substantially faster and retains the desirable property that the user doesn't
+# need to manually invoke a "make depend" step.
+#
+# As with the method described in the manual, we generate a separate dependency
+# (.d) file for each source file.  The .d file records the header files that
+# each C or C++ source file includes.  Any source file recorded in SRCS or
+# CXXSRCS will cause us to try and include the corresponding .d file and GNU
+# make then treats each .d file as a target to be remade.
+#
+# Unlike the manual's method, the rule we provide for making the .d file is
+# actually a fake.  All it does is record in a temporary file that the .d file
+# needs to be remade.  But as well as all the .d files, we also try to include
+# a file called "depend.phony".  This file never exists, but it causes GNU make
+# to try and make the target "depend.phony".  The rule for depend.phony then
+# looks at the temporary files generated by the .d rules and then invokes the
+# "omkdepend" program on all of the source files in one go.
+#
+
+#
+# We use simple assignment here to remove any of the depend.tmp files
+# at the time make parses this bit.
+#
+
+dummyvariable := $(shell $(RM) cdepend.tmp cxxdepend.tmp)
+
+#
+# Now the "fake" rules for generating .d files.
+#
+
+%.d: %.c
+	@echo "$<" >> cdepend.tmp
+
+%.d: %.cxx
+	@echo "$<" >> cxxdepend.tmp
+
+#
+# The depend.phony rule which actually runs omkdepend.
+#
+
+depend.phony:
+	@if [ -f cdepend.tmp ]; then \
+	   echo $(CMAKEDEPEND) $(ALL_CPPFLAGS) `cat cdepend.tmp`; \
+	   $(CMAKEDEPEND) $(ALL_CPPFLAGS) `cat cdepend.tmp`; \
+	   rm -f cdepend.tmp; \
+	 fi; \
+	 if [ -f cxxdepend.tmp ]; then \
+	   echo $(CXXMAKEDEPEND) $(ALL_CPPFLAGS) `cat cxxdepend.tmp`; \
+	   $(CXXMAKEDEPEND) $(ALL_CPPFLAGS) `cat cxxdepend.tmp`; \
+	   rm -f cxxdepend.tmp; \
+	 fi
+
+#
+# Now include the .d files and the "depend.phony" file which never exists.
+# For some reason GNU make evaluates the targets in reverse order, so we need
+# to include depend.phony first.  The "-" tells make not to complain that it
+# can't find the file.
+#
+
+-include depend.phony
+
+ifdef SRCS
+-include $(patsubst %.c,%.d,$(patsubst %.cxx,%.d,$(SRCS)))
+endif