diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index fec2dcbb681..608ea545ad7 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2021-05-26  Nelson Chu  <nelson.chu@sifive.com>
+
+	* elfxx-riscv.h (check_unknown_prefixed_ext): New bool.
+	* elfxx-riscv.c (riscv_parse_prefixed_ext): Do not check the
+	prefixed extension name if check_unknown_prefixed_ext is false.
+	* elfnn-riscv.c (riscv_merge_arch_attr_info): Set
+	check_unknown_prefixed_ext to false for linker.
+
 2021-05-25  Nick Clifton  <nickc@redhat.com>
 
 	* elf32-arn.c (struct elf_arm_obj_tdata): Add num_entries field.
diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 2068edebdb6..d2781f30993 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -3558,11 +3558,13 @@ riscv_merge_arch_attr_info (bfd *ibfd, char *in_arch, char *out_arch)
   rpe_in.error_handler = _bfd_error_handler;
   rpe_in.xlen = &xlen_in;
   rpe_in.get_default_version = NULL;
+  rpe_in.check_unknown_prefixed_ext = false;
 
   rpe_out.subset_list = &out_subsets;
   rpe_out.error_handler = _bfd_error_handler;
   rpe_out.xlen = &xlen_out;
   rpe_out.get_default_version = NULL;
+  rpe_out.check_unknown_prefixed_ext = false;
 
   if (in_arch == NULL && out_arch == NULL)
     return NULL;
diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index 7206ec8573b..39b69e2b0a5 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -1681,7 +1681,8 @@ riscv_parse_prefixed_ext (riscv_parse_subset_t *rps,
 	 and cannot simply be the prefixed name.  */
 
       /* Check that the extension name is well-formed.  */
-      if (!riscv_valid_prefixed_ext (subset))
+      if (rps->check_unknown_prefixed_ext
+	  && !riscv_valid_prefixed_ext (subset))
 	{
 	  rps->error_handler
 	    (_("-march=%s: unknown prefixed ISA extension `%s'"),
diff --git a/bfd/elfxx-riscv.h b/bfd/elfxx-riscv.h
index ff18ff6f0b8..c2fff926086 100644
--- a/bfd/elfxx-riscv.h
+++ b/bfd/elfxx-riscv.h
@@ -74,6 +74,7 @@ typedef struct
   void (*get_default_version) (const char *,
 			       int *,
 			       int *);
+  bool check_unknown_prefixed_ext;
 } riscv_parse_subset_t;
 
 extern bool
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 45cce1b99d0..eac946f13c1 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2021-05-26  Nelson Chu  <nelson.chu@sifive.com>
+
+	* config/tc-riscv.c (riscv_set_arch): Set
+	check_unknown_prefixed_ext to true for assembler.
+
 2021-05-25  Tamar Christina  <tamar.christina@arm.com>
 
 	PR gas/25235
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index a76e53d51c3..42e57529369 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -410,6 +410,7 @@ riscv_set_arch (const char *s)
   rps.error_handler = as_bad;
   rps.xlen = &xlen;
   rps.get_default_version = riscv_get_default_ext_version;
+  rps.check_unknown_prefixed_ext = true;
 
   if (s == NULL)
     return;