Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -85,7 +85,7 @@ all: top-all
 YOSYS_SRC := $(dir $(firstword $(MAKEFILE_LIST)))
 VPATH := $(YOSYS_SRC)
 
-CXXFLAGS := $(CXXFLAGS) -Wall -Wextra -ggdb -I. -I"$(YOSYS_SRC)" -MD -MP -D_YOSYS_ -fPIC -I$(PREFIX)/include
+CXXFLAGS := $(CXXFLAGS) -Wall -Wextra -I. -I"$(YOSYS_SRC)" -MD -MP -D_YOSYS_ -fPIC -I$(PREFIX)/include
 LDLIBS := $(LDLIBS) -lstdc++ -lm
 PLUGIN_LDFLAGS :=
 
@@ -349,6 +349,10 @@ else ifneq ($(CONFIG),none)
 $(error Invalid CONFIG setting '$(CONFIG)'. Valid values: clang, gcc, gcc-4.8, emcc, mxe, msys2-32, msys2-64)
 endif
 
+ifeq ($(OS), OpenBSD)
+LDLIBS := $(filter-out -lrt, $(LDLIBS))
+endif
+
 ifeq ($(ENABLE_LIBYOSYS),1)
 TARGETS += libyosys.so
 endif
@@ -439,7 +443,7 @@ endif
 ifeq ($(ENABLE_PLUGINS),1)
 CXXFLAGS += $(shell PKG_CONFIG_PATH=$(PKG_CONFIG_PATH) $(PKG_CONFIG) --silence-errors --cflags libffi) -DYOSYS_ENABLE_PLUGINS
 LDLIBS += $(shell PKG_CONFIG_PATH=$(PKG_CONFIG_PATH) $(PKG_CONFIG) --silence-errors --libs libffi || echo -lffi)
-ifneq ($(OS), FreeBSD)
+ifneq ($(OS), $(filter $(OS), FreeBSD OpenBSD))
 LDLIBS += -ldl
 endif
 endif