Index: sys/conf/files.riscv
===================================================================
--- sys/conf/files.riscv
+++ sys/conf/files.riscv
@@ -23,12 +23,6 @@
 kern/subr_intr.c		standard
 kern/subr_physmem.c		standard
 libkern/bcopy.c			standard
-libkern/ffs.c			standard
-libkern/ffsl.c			standard
-libkern/ffsll.c			standard
-libkern/fls.c			standard
-libkern/flsl.c			standard
-libkern/flsll.c			standard
 libkern/memcmp.c		standard
 libkern/memset.c		standard
 libkern/strcmp.c		standard
Index: sys/riscv/include/cpufunc.h
===================================================================
--- sys/riscv/include/cpufunc.h
+++ sys/riscv/include/cpufunc.h
@@ -46,6 +46,63 @@
 
 #ifdef _KERNEL
 
+#define	HAVE_INLINE_FFS
+
+static __inline __pure2 int
+ffs(int mask)
+{
+
+	return (__builtin_ffs(mask));
+}
+
+#define	HAVE_INLINE_FFSL
+
+static __inline __pure2 int
+ffsl(long mask)
+{
+
+	return (__builtin_ffsl(mask));
+}
+
+#define	HAVE_INLINE_FFSLL
+
+static __inline __pure2 int
+ffsll(long long mask)
+{
+
+	return (__builtin_ffsll(mask));
+}
+
+#define	HAVE_INLINE_FLS
+
+static __inline __pure2 int
+fls(int mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clz((u_int)mask));
+}
+
+#define	HAVE_INLINE_FLSL
+
+static __inline __pure2 int
+flsl(long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzl((u_long)mask));
+}
+
+#define	HAVE_INLINE_FLSLL
+
+static __inline __pure2 int
+flsll(long long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzll((unsigned long long)mask));
+}
+
 #include <machine/riscvreg.h>
 
 static __inline register_t