diff --git a/sys/amd64/include/cpufunc.h b/sys/amd64/include/cpufunc.h
--- a/sys/amd64/include/cpufunc.h
+++ b/sys/amd64/include/cpufunc.h
@@ -127,43 +127,6 @@
 	__asm __volatile("sti");
 }
 
-#ifdef _KERNEL
-
-#define	HAVE_INLINE_FFS
-#define	ffs(x)		__builtin_ffs(x)
-
-#define	HAVE_INLINE_FFSL
-#define	ffsl(x)		__builtin_ffsl(x)
-
-#define	HAVE_INLINE_FFSLL
-#define	ffsll(x)	__builtin_ffsll(x)
-
-#define	HAVE_INLINE_FLS
-
-static __inline __pure2 int
-fls(int mask)
-{
-	return (mask == 0 ? mask : (int)bsrl((u_int)mask) + 1);
-}
-
-#define	HAVE_INLINE_FLSL
-
-static __inline __pure2 int
-flsl(long mask)
-{
-	return (mask == 0 ? mask : (int)bsrq((u_long)mask) + 1);
-}
-
-#define	HAVE_INLINE_FLSLL
-
-static __inline __pure2 int
-flsll(long long mask)
-{
-	return (flsl((long)mask));
-}
-
-#endif /* _KERNEL */
-
 static __inline void
 halt(void)
 {
diff --git a/sys/arm/include/cpufunc.h b/sys/arm/include/cpufunc.h
--- a/sys/arm/include/cpufunc.h
+++ b/sys/arm/include/cpufunc.h
@@ -183,63 +183,6 @@
 extern int	arm_dcache_align;
 extern int	arm_dcache_align_mask;
 
-
-#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));
-}
 #else	/* !_KERNEL */
 
 static __inline void
diff --git a/sys/arm64/include/cpufunc.h b/sys/arm64/include/cpufunc.h
--- a/sys/arm64/include/cpufunc.h
+++ b/sys/arm64/include/cpufunc.h
@@ -37,64 +37,6 @@
 }
 
 #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/armreg.h>
 
 void pan_enable(void);
diff --git a/sys/conf/files.i386 b/sys/conf/files.i386
--- a/sys/conf/files.i386
+++ b/sys/conf/files.i386
@@ -140,8 +140,6 @@
 kern/imgact_aout.c		optional compat_aout
 kern/subr_sfbuf.c		standard
 libkern/divdi3.c		standard
-libkern/ffsll.c			standard
-libkern/flsll.c			standard
 libkern/memcmp.c		standard
 libkern/memset.c		standard
 libkern/moddi3.c		standard
diff --git a/sys/conf/files.powerpc b/sys/conf/files.powerpc
--- a/sys/conf/files.powerpc
+++ b/sys/conf/files.powerpc
@@ -189,10 +189,6 @@
 libkern/bcopy.c			standard
 libkern/cmpdi2.c		optional	powerpc | powerpcspe
 libkern/divdi3.c		optional	powerpc | powerpcspe
-libkern/ffs.c			standard
-libkern/ffsl.c			standard
-libkern/ffsll.c			standard
-libkern/flsll.c			standard
 libkern/lshrdi3.c		optional	powerpc | powerpcspe
 libkern/memcmp.c		standard
 libkern/memset.c		standard
diff --git a/sys/conf/files.riscv b/sys/conf/files.riscv
--- a/sys/conf/files.riscv
+++ b/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
diff --git a/sys/i386/include/cpufunc.h b/sys/i386/include/cpufunc.h
--- a/sys/i386/include/cpufunc.h
+++ b/sys/i386/include/cpufunc.h
@@ -180,48 +180,6 @@
 	__asm __volatile("sfence" : : : "memory");
 }
 
-#ifdef _KERNEL
-
-#define	HAVE_INLINE_FFS
-
-static __inline __pure2 int
-ffs(int mask)
-{
-	/*
-	 * Note that gcc-2's builtin ffs would be used if we didn't declare
-	 * this inline or turn off the builtin.  The builtin is faster but
-	 * broken in gcc-2.4.5 and slower but working in gcc-2.5 and later
-	 * versions.
-	 */
-	 return (mask == 0 ? mask : (int)bsfl((u_int)mask) + 1);
-}
-
-#define	HAVE_INLINE_FFSL
-
-static __inline __pure2 int
-ffsl(long mask)
-{
-	return (ffs((int)mask));
-}
-
-#define	HAVE_INLINE_FLS
-
-static __inline __pure2 int
-fls(int mask)
-{
-	return (mask == 0 ? mask : (int)bsrl((u_int)mask) + 1);
-}
-
-#define	HAVE_INLINE_FLSL
-
-static __inline __pure2 int
-flsl(long mask)
-{
-	return (fls((int)mask));
-}
-
-#endif /* _KERNEL */
-
 static __inline void
 halt(void)
 {
diff --git a/sys/powerpc/include/cpufunc.h b/sys/powerpc/include/cpufunc.h
--- a/sys/powerpc/include/cpufunc.h
+++ b/sys/powerpc/include/cpufunc.h
@@ -258,20 +258,6 @@
 	return (ret);
 }
 
-#define	HAVE_INLINE_FLS
-static __inline __pure2 int
-fls(int mask)
-{
-	return (mask ? 32 - __builtin_clz(mask) : 0);
-}
-
-#define HAVE_INLINE_FLSL
-static __inline __pure2 int
-flsl(long mask)
-{
-	return (mask ? (8 * sizeof(long) - __builtin_clzl(mask)) : 0);
-}
-
 /* "NOP" operations to signify priorities to the kernel. */
 static __inline void
 nop_prio_vlow(void)
diff --git a/sys/sys/libkern.h b/sys/sys/libkern.h
--- a/sys/sys/libkern.h
+++ b/sys/sys/libkern.h
@@ -132,24 +132,66 @@
 int	 timingsafe_bcmp(const void *, const void *, size_t);
 void	*bsearch(const void *, const void *, size_t,
 	    size_t, int (*)(const void *, const void *));
-#ifndef	HAVE_INLINE_FFS
-int	 ffs(int);
-#endif
-#ifndef	HAVE_INLINE_FFSL
-int	 ffsl(long);
-#endif
-#ifndef	HAVE_INLINE_FFSLL
-int	 ffsll(long long);
-#endif
-#ifndef	HAVE_INLINE_FLS
-int	 fls(int);
-#endif
-#ifndef	HAVE_INLINE_FLSL
-int	 flsl(long);
-#endif
-#ifndef	HAVE_INLINE_FLSLL
-int	 flsll(long long);
-#endif
+
+/*
+ * Find First Set bit (ffs) and Find Last Set bit (fls) family of functions.
+ * These definitions may be overridden by machine/cpufunc.h.
+ *
+ * MHTODO: remove the 'HAVE_INLINE_FOO' defines once use of these flags has
+ * been purged everywhere. For now we provide them unconditionally.
+ */
+#define	HAVE_INLINE_FFS
+#define	HAVE_INLINE_FFSL
+#define	HAVE_INLINE_FFSLL
+#define	HAVE_INLINE_FLS
+#define	HAVE_INLINE_FLSL
+#define	HAVE_INLINE_FLSLL
+
+static __inline __pure2 int
+ffs(int mask)
+{
+
+	return (__builtin_ffs((u_int)mask));
+}
+
+static __inline __pure2 int
+ffsl(long mask)
+{
+
+	return (__builtin_ffsl((u_long)mask));
+}
+
+static __inline __pure2 int
+ffsll(long long mask)
+{
+
+	return (__builtin_ffsll((unsigned long long)mask));
+}
+
+static __inline __pure2 int
+fls(int mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clz((u_int)mask));
+}
+
+static __inline __pure2 int
+flsl(long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzl((u_long)mask));
+}
+
+static __inline __pure2 int
+flsll(long long mask)
+{
+
+	return (mask == 0 ? 0 :
+	    8 * sizeof(mask) - __builtin_clzll((unsigned long long)mask));
+}
+
 #define	bitcount64(x)	__bitcount64((uint64_t)(x))
 #define	bitcount32(x)	__bitcount32((uint32_t)(x))
 #define	bitcount16(x)	__bitcount16((uint16_t)(x))