diff --git a/techlibs/xilinx/Makefile.inc b/techlibs/xilinx/Makefile.inc
index ae82311a9..10d783c3c 100644
--- a/techlibs/xilinx/Makefile.inc
+++ b/techlibs/xilinx/Makefile.inc
@@ -1,5 +1,6 @@
 
 OBJS += techlibs/xilinx/synth_xilinx.o
+OBJS += techlibs/xilinx/xilinx_finalise.o
 
 GENFILES += techlibs/xilinx/brams_init_36.vh
 GENFILES += techlibs/xilinx/brams_init_32.vh
diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index 022b0d108..c2f8279c2 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -512,6 +512,8 @@ struct SynthXilinxPass : public ScriptPass
 				run("iopadmap -bits -outpad OBUF I:O -inpad IBUF O:I A:top", "(only if '-iopad' or '-ise' and not '-noiopad')");
 			if (help_mode || ise)
 				run("extractinv -inv INV O:I", "(only if '-ise')");
+			if (help_mode || !nodsp)
+				run("xilinx_finalise", "(skip if '-nodsp')");
 		}
 
 		if (check_label("check")) {
diff --git a/techlibs/xilinx/xilinx_finalise.cc b/techlibs/xilinx/xilinx_finalise.cc
new file mode 100644
index 000000000..db73babe3
--- /dev/null
+++ b/techlibs/xilinx/xilinx_finalise.cc
@@ -0,0 +1,84 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *            (C) 2019  Eddie Hung    <eddie@fpgeh.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/register.h"
+#include "kernel/celltypes.h"
+#include "kernel/rtlil.h"
+#include "kernel/log.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct XilinxFinalisePass : public Pass
+{
+	XilinxFinalisePass() : Pass("xilinx_finalise", "") { }
+
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    xilinx_finalise [options]\n");
+		log("\n");
+	}
+
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		log_header(design, "Executing XILINX_FINALISE pass.\n");
+
+		for (auto module : design->selected_modules())
+		for (auto cell : module->selected_cells()) {
+			if (cell->type != ID(DSP48E1))
+				continue;
+			for (auto &conn : cell->connections_) {
+				if (!cell->output(conn.first))
+					continue;
+				bool purge = true;
+				for (auto &chunk : conn.second.chunks()) {
+					auto it = chunk.wire->attributes.find(ID(unused_bits));
+					if (it == chunk.wire->attributes.end())
+						continue;
+
+					std::string unused_bits = stringf("%d", chunk.offset);
+					for (auto i = 1; i < chunk.width; i++)
+						unused_bits += stringf(" %d", i+chunk.offset);
+
+					if (it->second.decode_string().find(unused_bits) == std::string::npos) {
+						purge = false;
+						break;
+					}
+				}
+
+				if (purge) {
+					log_debug("Purging unused port connection %s %s (.%s(%s))\n", cell->type.c_str(), log_id(cell), log_id(conn.first), log_signal(conn.second));
+					conn.second = SigSpec();
+				}
+			}
+		}
+	}
+} XilinxFinalisePass;
+
+PRIVATE_NAMESPACE_END