diff --git a/passes/cmds/splitnets.cc b/passes/cmds/splitnets.cc
index bd8b9ceac..388f125d8 100644
--- a/passes/cmds/splitnets.cc
+++ b/passes/cmds/splitnets.cc
@@ -112,6 +112,12 @@ struct SplitnetsPass : public Pass {
 		log("    -ports\n");
 		log("        also split module ports. per default only internal signals are split.\n");
 		log("\n");
+		log("    -ports_only\n");
+		log("        split module ports, but not the internal signals.\n");
+		log("\n");
+		log("    -top_only\n");
+		log("        split module ports/nets, only at the top level of hierarchy.\n");
+		log("\n");
 		log("    -driver\n");
 		log("        don't blindly split nets in individual bits. instead look at the driver\n");
 		log("        and split nets so that no driver drives only part of a net.\n");
@@ -121,6 +127,8 @@ struct SplitnetsPass : public Pass {
 	{
 		bool flag_ports = false;
 		bool flag_driver = false;
+		bool flag_ports_only = false;
+		bool flag_top_only = false;
 		std::string format = "[]:";
 
 		log_header(design, "Executing SPLITNETS pass (splitting up multi-bit signals).\n");
@@ -136,6 +144,14 @@ struct SplitnetsPass : public Pass {
 				flag_ports = true;
 				continue;
 			}
+			if (args[argidx] == "-ports_only") {
+				flag_ports_only = true;
+				continue;
+			}
+			if (args[argidx] == "-top_only") {
+			  flag_top_only = true;
+				continue;
+			}
 			if (args[argidx] == "-driver") {
 				flag_driver = true;
 				continue;
@@ -151,10 +167,12 @@ struct SplitnetsPass : public Pass {
 		{
 			if (module->has_processes_warn())
 				continue;
+			if (flag_top_only && (design->top_module() != module))
+				continue;
 
 			SplitnetsWorker worker;
 
-			if (flag_ports)
+			if (flag_ports || flag_ports_only)
 			{
 				int normalized_port_factor = 0;
 
@@ -186,7 +204,8 @@ struct SplitnetsPass : public Pass {
 					for (auto &chunk : sig.chunks()) {
 						if (chunk.wire == NULL)
 							continue;
-						if (chunk.wire->port_id == 0 || flag_ports) {
+						if ((flag_ports_only && (chunk.wire->port_id != 0) ||
+						   (!flag_ports_only && (chunk.wire->port_id == 0 || flag_ports))) {
 							if (chunk.offset != 0)
 								split_wires_at[chunk.wire].insert(chunk.offset);
 							if (chunk.offset + chunk.width < chunk.wire->width)
@@ -207,7 +226,10 @@ struct SplitnetsPass : public Pass {
 			else
 			{
 				for (auto wire : module->wires()) {
-					if (wire->width > 1 && (wire->port_id == 0 || flag_ports) && design->selected(module, wire))
+					if (flag_ports_only)
+						if (wire->width > 1 && (wire->port_id != 0) && design->selected(module, wire))
+							worker.splitmap[wire] = std::vector<RTLIL::SigBit>();
+					else if (wire->width > 1 && (wire->port_id == 0 || flag_ports) && design->selected(module, wire))
 						worker.splitmap[wire] = std::vector<RTLIL::SigBit>();
 				}
 
@@ -218,7 +240,7 @@ struct SplitnetsPass : public Pass {
 
 			module->rewrite_sigspecs(worker);
 
-			if (flag_ports)
+			if (flag_ports || flag_ports_only)
 			{
 				for (auto wire : module->wires())
 				{
@@ -243,7 +265,7 @@ struct SplitnetsPass : public Pass {
 				delete_wires.insert(it.first);
 			module->remove(delete_wires);
 
-			if (flag_ports)
+			if (flag_ports || flag_ports_only)
 				module->fixup_ports();
 		}
 
diff --git a/tests/various/test_splitnets.tcl b/tests/various/test_splitnets.tcl
new file mode 100644
index 000000000..9cb2b4305
--- /dev/null
+++ b/tests/various/test_splitnets.tcl
@@ -0,0 +1,63 @@
+yosys -import
+
+proc read_stats { file } {
+    set fid [open $file]
+    set result [read $fid]
+    close $fid
+    set ports 0
+    set nets 0
+    foreach line [split $result "\n"] {
+	if [regexp {Number of wires:[ \t]+([0-9]+)} $line tmp n] {
+	    set nets [expr $nets + $n]
+	}
+	if [regexp {Number of ports:[ \t]+([0-9]+)} $line tmp n] {
+	    set ports [expr $ports + $n]
+	}
+    }
+    return [list $nets $ports]
+}
+
+proc assert_count { type actual expected } {
+    if {$actual != $expected} {
+	puts "Error, $type count: $actual vs $expected expected"
+	exit 1
+    }
+}
+
+read_verilog test_splitnets.v
+hierarchy -auto-top
+procs
+design -save "pre"
+
+splitnets -ports_only -top_only
+write_verilog -noexpr "ports_only_in_top.v"
+tee -o "ports_only_in_top.txt" stat
+foreach {nets ports} [read_stats "ports_only_in_top.txt"] {}
+assert_count "nets" $nets 26
+assert_count "ports" $ports 16
+
+design -load "pre"
+splitnets -ports_only
+write_verilog -noexpr "ports_only_in_all.v"
+tee -o "ports_only_in_all.txt" stat
+foreach {nets ports} [read_stats "ports_only_in_all.txt"] {}
+assert_count "nets" $nets 30
+assert_count "ports" $ports 20
+
+design -load "pre"
+splitnets -ports -top_only
+write_verilog -noexpr "ports_nets_in_top.v"
+tee -o "ports_nets_in_top.txt" stat
+foreach {nets ports} [read_stats "ports_nets_in_top.txt"] {}
+assert_count "nets" $nets 30
+assert_count "ports" $ports 16
+
+design -load "pre"
+splitnets -ports
+write_verilog -noexpr "ports_nets_in_all.v"
+tee -o "ports_nets_in_all.txt" stat
+foreach {nets ports} [read_stats "ports_nets_in_all.txt"] {}
+assert_count "nets" $nets 40
+assert_count "ports" $ports 20
+
+exit 0
diff --git a/tests/various/test_splitnets.v b/tests/various/test_splitnets.v
new file mode 100644
index 000000000..2833ce147
--- /dev/null
+++ b/tests/various/test_splitnets.v
@@ -0,0 +1,13 @@
+module bottom(input clk, input wire [1:0] i, output reg [1:0] q);
+  reg [1:0] q1;
+  always @(posedge clk) begin
+     q1 <= i;
+     q <= q1;
+  end
+endmodule
+
+module top(input clk, input wire [1:0] i, output reg [1:0] q);
+  reg [1:0] q1;
+  bottom u1 (.clk(clk), .i(i), .q(q1));
+  not u2 (q, q1);
+endmodule
diff --git a/tests/various/test_splitnets.ys b/tests/various/test_splitnets.ys
new file mode 100644
index 000000000..2af787d4f
--- /dev/null
+++ b/tests/various/test_splitnets.ys
@@ -0,0 +1 @@
+tcl test_splitnets.tcl