diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 92bda1a7e14..c3001c6ded9 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -6253,6 +6253,9 @@ stores.
 This hook should set @var{vecsize_mangle}, @var{vecsize_int}, @var{vecsize_float}
 fields in @var{simd_clone} structure pointed by @var{clone_info} argument and also
 @var{simdlen} field if it was previously 0.
+@var{vecsize_mangle} is a marker for the backend only. @var{vecsize_int} and
+@var{vecsize_float} should be left zero on targets where the number of lanes is
+not determined by the bitsize (in which case @var{simdlen} is always used).
 The hook should return 0 if SIMD clones shouldn't be emitted,
 or number of @var{vecsize_mangle} variants that should be emitted.
 @end deftypefn
diff --git a/gcc/omp-simd-clone.cc b/gcc/omp-simd-clone.cc
index 58bd68b129b..258d3c6377f 100644
--- a/gcc/omp-simd-clone.cc
+++ b/gcc/omp-simd-clone.cc
@@ -504,7 +504,10 @@ simd_clone_adjust_return_type (struct cgraph_node *node)
     veclen = node->simdclone->vecsize_int;
   else
     veclen = node->simdclone->vecsize_float;
-  veclen = exact_div (veclen, GET_MODE_BITSIZE (SCALAR_TYPE_MODE (t)));
+  if (known_eq (veclen, 0))
+    veclen = node->simdclone->simdlen;
+  else
+    veclen = exact_div (veclen, GET_MODE_BITSIZE (SCALAR_TYPE_MODE (t)));
   if (multiple_p (veclen, node->simdclone->simdlen))
     veclen = node->simdclone->simdlen;
   if (POINTER_TYPE_P (t))
@@ -618,8 +621,12 @@ simd_clone_adjust_argument_types (struct cgraph_node *node)
 	    veclen = sc->vecsize_int;
 	  else
 	    veclen = sc->vecsize_float;
-	  veclen = exact_div (veclen,
-			      GET_MODE_BITSIZE (SCALAR_TYPE_MODE (parm_type)));
+	  if (known_eq (veclen, 0))
+	    veclen = sc->simdlen;
+	  else
+	    veclen = exact_div (veclen,
+				GET_MODE_BITSIZE
+				(SCALAR_TYPE_MODE (parm_type)));
 	  if (multiple_p (veclen, sc->simdlen))
 	    veclen = sc->simdlen;
 	  adj.op = IPA_PARAM_OP_NEW;
@@ -669,8 +676,11 @@ simd_clone_adjust_argument_types (struct cgraph_node *node)
 	veclen = sc->vecsize_int;
       else
 	veclen = sc->vecsize_float;
-      veclen = exact_div (veclen,
-			  GET_MODE_BITSIZE (SCALAR_TYPE_MODE (base_type)));
+      if (known_eq (veclen, 0))
+	veclen = sc->simdlen;
+      else
+	veclen = exact_div (veclen,
+			    GET_MODE_BITSIZE (SCALAR_TYPE_MODE (base_type)));
       if (multiple_p (veclen, sc->simdlen))
 	veclen = sc->simdlen;
       if (sc->mask_mode != VOIDmode)
diff --git a/gcc/target.def b/gcc/target.def
index 2a7fa68f83d..4d49ffc2c88 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -1629,6 +1629,9 @@ DEFHOOK
 "This hook should set @var{vecsize_mangle}, @var{vecsize_int}, @var{vecsize_float}\n\
 fields in @var{simd_clone} structure pointed by @var{clone_info} argument and also\n\
 @var{simdlen} field if it was previously 0.\n\
+@var{vecsize_mangle} is a marker for the backend only. @var{vecsize_int} and\n\
+@var{vecsize_float} should be left zero on targets where the number of lanes is\n\
+not determined by the bitsize (in which case @var{simdlen} is always used).\n\
 The hook should return 0 if SIMD clones shouldn't be emitted,\n\
 or number of @var{vecsize_mangle} variants that should be emitted.",
 int, (struct cgraph_node *, struct cgraph_simd_clone *, tree, int), NULL)