diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 4829ff8aaad..a52ac8b77cc 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -938,8 +938,8 @@ const relax_typeS md_relax_table[] =
 
 static const arch_entry cpu_arch[] =
 {
-  /* Do not replace the first two entries - i386_target_format()
-     relies on them being there in this order.  */
+  /* Do not replace the first two entries - i386_target_format() and
+     set_cpu_arch() rely on them being there in this order.  */
   ARCH (generic32, GENERIC32, GENERIC32, false),
   ARCH (generic64, GENERIC64, GENERIC64, false),
   ARCH (i8086, UNKNOWN, NONE, false),
@@ -2724,12 +2724,47 @@ set_cpu_arch (int dummy ATTRIBUTE_UNUSED)
 
   if (!is_end_of_line[(unsigned char) *input_line_pointer])
     {
-      char *string;
-      int e = get_symbol_name (&string);
-      unsigned int j;
+      char *s;
+      int e = get_symbol_name (&s);
+      const char *string = s;
+      unsigned int j = 0;
       i386_cpu_flags flags;
 
-      for (j = 0; j < ARRAY_SIZE (cpu_arch); j++)
+      if (strcmp (string, "default") == 0)
+	{
+	  if (strcmp (default_arch, "iamcu") == 0)
+	    string = default_arch;
+	  else
+	    {
+	      static const i386_cpu_flags cpu_unknown_flags = CPU_UNKNOWN_FLAGS;
+
+	      cpu_arch_name = NULL;
+	      free (cpu_sub_arch_name);
+	      cpu_sub_arch_name = NULL;
+	      cpu_arch_flags = cpu_unknown_flags;
+	      if (flag_code == CODE_64BIT)
+		{
+		  cpu_arch_flags.bitfield.cpu64 = 1;
+		  cpu_arch_flags.bitfield.cpuno64 = 0;
+		}
+	      else
+		{
+		  cpu_arch_flags.bitfield.cpu64 = 0;
+		  cpu_arch_flags.bitfield.cpuno64 = 1;
+		}
+	      cpu_arch_isa = PROCESSOR_UNKNOWN;
+	      cpu_arch_isa_flags = cpu_arch[flag_code == CODE_64BIT].flags;
+	      if (!cpu_arch_tune_set)
+		{
+		  cpu_arch_tune = cpu_arch_isa;
+		  cpu_arch_tune_flags = cpu_arch_isa_flags;
+		}
+
+	      j = ARRAY_SIZE (cpu_arch) + 1;
+	    }
+	}
+
+      for (; j < ARRAY_SIZE (cpu_arch); j++)
 	{
 	  if (strcmp (string, cpu_arch[j].name) == 0)
 	    {
@@ -2802,7 +2837,7 @@ set_cpu_arch (int dummy ATTRIBUTE_UNUSED)
 	  j = ARRAY_SIZE (cpu_arch);
 	}
 
-      if (j >= ARRAY_SIZE (cpu_arch))
+      if (j == ARRAY_SIZE (cpu_arch))
 	as_bad (_("no such architecture: `%s'"), string);
 
       *input_line_pointer = e;
@@ -13676,6 +13711,13 @@ show_arch (FILE *stream, int ext, int check)
 
   p = start;
   left = size - (start - message);
+
+  if (!ext && check)
+    {
+      p = output_message (stream, p, message, start, &left,
+			  STRING_COMMA_LEN ("default"));
+    }
+
   for (j = 0; j < ARRAY_SIZE (cpu_arch); j++)
     {
       /* Should it be skipped?  */
diff --git a/gas/doc/c-i386.texi b/gas/doc/c-i386.texi
index 5262af2023b..95fd8ec9dc9 100644
--- a/gas/doc/c-i386.texi
+++ b/gas/doc/c-i386.texi
@@ -1504,6 +1504,7 @@ directive enables a warning when gas detects an instruction that is not
 supported on the CPU specified.  The choices for @var{cpu_type} are:
 
 @multitable @columnfractions .20 .20 .20 .20
+@item @samp{default}
 @item @samp{i8086} @tab @samp{i186} @tab @samp{i286} @tab @samp{i386}
 @item @samp{i486} @tab @samp{i586} @tab @samp{i686} @tab @samp{pentium}
 @item @samp{pentiumpro} @tab @samp{pentiumii} @tab @samp{pentiumiii} @tab @samp{pentium4}
@@ -1531,7 +1532,7 @@ supported on the CPU specified.  The choices for @var{cpu_type} are:
 @item @samp{.avx512_vpopcntdq} @tab @samp{.avx512_vbmi2} @tab @samp{.avx512_vnni}
 @item @samp{.avx512_bitalg} @tab @samp{.avx512_bf16} @tab @samp{.avx512_vp2intersect}
 @item @samp{.tdx} @tab @samp{.avx_vnni}  @tab @samp{.avx512_fp16}
-@item @samp{.clwb} @tab @samp{.rdpid} @tab @samp{.ptwrite} @tab @item @samp{.ibt}
+@item @samp{.clwb} @tab @samp{.rdpid} @tab @samp{.ptwrite} @tab @samp{.ibt}
 @item @samp{.wbnoinvd} @tab @samp{.pconfig} @tab @samp{.waitpkg} @tab @samp{.cldemote}
 @item @samp{.shstk} @tab @samp{.gfni} @tab @samp{.vaes} @tab @samp{.vpclmulqdq}
 @item @samp{.movdiri} @tab @samp{.movdir64b} @tab @samp{.enqcmd} @tab @samp{.tsxldtrk}
diff --git a/gas/testsuite/gas/i386/arch-dflt.l b/gas/testsuite/gas/i386/arch-dflt.l
new file mode 100644
index 00000000000..d0953b1f86d
--- /dev/null
+++ b/gas/testsuite/gas/i386/arch-dflt.l
@@ -0,0 +1,19 @@
+.*: Assembler messages:
+.*:3: Error:.*`cmovl'.*
+.*:9: Error:.*`cmovg'.*
+GAS LISTING .*
+
+
+[ 	]*[0-9]*[ 	]+\.text
+[ 	]*[0-9]*[ 	]+start:
+[ 	]*[0-9]*[ 	]+cmovl	%eax, %ecx
+[ 	]*[0-9]*[ 	]*
+[ 	]*[0-9]*[ 	]+\.arch default
+[ 	]*[0-9]*[ 	]+\?\?\?\? 0F4DC8[ 	]+cmovnl	%eax, %ecx
+[ 	]*[0-9]*[ 	]*
+[ 	]*[0-9]*[ 	]+\.arch generic32
+[ 	]*[0-9]*[ 	]+cmovg	%eax, %ecx
+[ 	]*[0-9]*[ 	]*
+[ 	]*[0-9]*[ 	]+\.arch default
+[ 	]*[0-9]*[ 	]+\?\?\?\? 0F4EC8[ 	]+cmovng	%eax, %ecx
+#pass
diff --git a/gas/testsuite/gas/i386/arch-dflt.s b/gas/testsuite/gas/i386/arch-dflt.s
new file mode 100644
index 00000000000..718bf6f4d51
--- /dev/null
+++ b/gas/testsuite/gas/i386/arch-dflt.s
@@ -0,0 +1,14 @@
+	.text
+start:
+	cmovl	%eax, %ecx
+
+	.arch default
+	cmovnl	%eax, %ecx
+
+	.arch generic32
+	cmovg	%eax, %ecx
+
+	.arch default
+	cmovng	%eax, %ecx
+
+	.end
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index ebb1b492462..de4eb1cfba5 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -205,6 +205,7 @@ if [gas_32_check] then {
     run_dump_test "arch-12"
     run_dump_test "arch-13"
     run_dump_test "arch-14"
+    run_list_test "arch-dflt" "-march=generic32 -al"
     run_dump_test "8087"
     run_dump_test "287"
     run_dump_test "387"