diff --git a/Makefrag b/Makefrag
index 49cd2802..f02fb454 100644
--- a/Makefrag
+++ b/Makefrag
@@ -82,3 +82,6 @@ $(consts_header_debug): $(params_file_debug)
 	sed -r 's/\(([A-Za-z0-9_]+),([A-Za-z0-9_]+)\)/#define \1 \2/' $< >> $@
 	echo "#define TBFRAG \"$(MODEL).$(CONFIG).tb.cpp\"" >> $@
 	echo "#endif // __CONST_H__" >> $@
+
+clean-run-output:
+	rm -f $(output_dir)/{*.out,*.run,*.vpd}
diff --git a/regression/Makefile b/regression/Makefile
index a0c55ce4..7303a91b 100644
--- a/regression/Makefile
+++ b/regression/Makefile
@@ -155,6 +155,7 @@ stamps/%/emulator-bmark-tests.stamp: stamps/other-submodules.stamp $(RISCV)/inst
 
 stamps/%/emulator-regression-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.stamp
 	mkdir -p $(dir $@)
+	$(MAKE) -C $(abspath $(TOP))/emulator CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) clean-run-output
 	$(MAKE) -C $(abspath $(TOP))/emulator CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) run-regression-tests-fast
 	date > $@
 
@@ -170,24 +171,10 @@ stamps/%/vsim-bmark-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.
 
 stamps/%/vsim-regression-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.stamp
 	mkdir -p $(dir $@)
+	$(MAKE) -C $(abspath $(TOP))/vsim CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) clean-run-output
 	$(MAKE) -C $(abspath $(TOP))/vsim CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) run-regression-tests-fast
 	date > $@
 
-stamps/%/fsim-asm-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.stamp
-	mkdir -p $(dir $@)
-	$(MAKE) -C $(abspath $(TOP))/fsim CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) run-asm-tests-fast
-	date > $@
-
-stamps/%/fsim-bmark-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.stamp
-	mkdir -p $(dir $@)
-	$(MAKE) -C $(abspath $(TOP))/fsim CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) run-bmark-tests-fast
-	date > $@
-
-stamps/%/fsim-regression-tests.stamp: stamps/other-submodules.stamp $(RISCV)/install.stamp
-	mkdir -p $(dir $@)
-	$(MAKE) -C $(abspath $(TOP))/fsim CONFIG=$* RISCV=$(abspath $(RISCV)) CHISEL_VERSION=$(CHISEL_VERSION) run-regression-tests-fast
-	date > $@
-
 # The torture tests run subtly differently on the different targets, so they
 # don't have pattern rules like everything else does.
 stamps/%/vsim-torture-$(TORTURE_CONFIG).stamp: stamps/%/vsim-debug.stamp stamps/%/vsim-ndebug.stamp