diff --git a/elf/cache.c b/elf/cache.c
index 11ce4ade8a..c01d302072 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -146,6 +146,7 @@ struct cache_entry
   struct stringtable_entry *path; /* Path to find library.  */
   int flags;			/* Flags to indicate kind of library.  */
   unsigned int osversion;	/* Required OS version.  */
+  unsigned int isa_level;	/* Required ISA level.  */
   uint64_t hwcap;		/* Important hardware capabilities.  */
   int bits_hwcap;		/* Number of bits set in hwcap.  */
 
@@ -549,6 +550,19 @@ write_extensions (int fd, uint32_t str_offset,
   free (ext);
 }
 
+/* Compute the hwcap value from ENTRY.  */
+static inline uint64_t
+compute_hwcap_value (struct cache_entry *entry)
+{
+  if (entry->isa_level > DL_CACHE_HWCAP_ISA_LEVEL_MASK)
+    error (EXIT_FAILURE, 0, _("%s: ISA level is too high (%d > %d)"),
+	   entry->path->string, entry->isa_level,
+	   DL_CACHE_HWCAP_ISA_LEVEL_MASK);
+  return (DL_CACHE_HWCAP_EXTENSION
+	  | (((uint64_t) entry->isa_level) << 32)
+	  | entry->hwcaps->section_index);
+}
+
 /* Save the contents of the cache.  */
 void
 save_cache (const char *cache_name)
@@ -662,7 +676,7 @@ save_cache (const char *cache_name)
 	    file_entries_new->libs[idx_new].hwcap = entry->hwcap;
 	  else
 	    file_entries_new->libs[idx_new].hwcap
-	      = DL_CACHE_HWCAP_EXTENSION | entry->hwcaps->section_index;
+	      = compute_hwcap_value (entry);
 	  file_entries_new->libs[idx_new].key
 	    = str_offset + entry->lib->offset;
 	  file_entries_new->libs[idx_new].value
@@ -777,7 +791,8 @@ save_cache (const char *cache_name)
 /* Add one library to the cache.  */
 void
 add_to_cache (const char *path, const char *filename, const char *soname,
-	      int flags, unsigned int osversion, uint64_t hwcap,
+	      int flags, unsigned int osversion,
+	      unsigned int isa_level, uint64_t hwcap,
 	      struct glibc_hwcaps_subdirectory *hwcaps)
 {
   struct cache_entry *new_entry = xmalloc (sizeof (*new_entry));
@@ -795,6 +810,7 @@ add_to_cache (const char *path, const char *filename, const char *soname,
   new_entry->path = path_interned;
   new_entry->flags = flags;
   new_entry->osversion = osversion;
+  new_entry->isa_level = isa_level;
   new_entry->hwcap = hwcap;
   new_entry->hwcaps = hwcaps;
   new_entry->bits_hwcap = 0;
@@ -851,6 +867,7 @@ struct aux_cache_entry
   struct aux_cache_entry_id id;
   int flags;
   unsigned int osversion;
+  unsigned int isa_level;
   int used;
   char *soname;
   struct aux_cache_entry *next;
@@ -864,7 +881,7 @@ struct aux_cache_file_entry
   int32_t flags;		/* This is 1 for an ELF library.  */
   uint32_t soname;		/* String table indice.  */
   uint32_t osversion;		/* Required OS version.	 */
-  int32_t pad;
+  uint32_t isa_level;		/* Required ISA level.	 */
 };
 
 /* ldconfig maintains an auxiliary cache file that allows
@@ -915,7 +932,8 @@ init_aux_cache (void)
 
 int
 search_aux_cache (struct stat64 *stat_buf, int *flags,
-		  unsigned int *osversion, char **soname)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname)
 {
   struct aux_cache_entry_id id;
   id.ino = (uint64_t) stat_buf->st_ino;
@@ -933,6 +951,7 @@ search_aux_cache (struct stat64 *stat_buf, int *flags,
       {
 	*flags = entry->flags;
 	*osversion = entry->osversion;
+	*isa_level = entry->isa_level;
 	if (entry->soname != NULL)
 	  *soname = xstrdup (entry->soname);
 	else
@@ -946,7 +965,8 @@ search_aux_cache (struct stat64 *stat_buf, int *flags,
 
 static void
 insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
-		     unsigned int osversion, const char *soname, int used)
+		     unsigned int osversion, unsigned int isa_level,
+		     const char *soname, int used)
 {
   size_t hash = aux_cache_entry_id_hash (id) % aux_hash_size;
   struct aux_cache_entry *entry;
@@ -962,6 +982,7 @@ insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
   entry->id = *id;
   entry->flags = flags;
   entry->osversion = osversion;
+  entry->isa_level = isa_level;
   entry->used = used;
   if (soname != NULL)
     entry->soname = memcpy ((char *) (entry + 1), soname, len);
@@ -973,14 +994,15 @@ insert_to_aux_cache (struct aux_cache_entry_id *id, int flags,
 
 void
 add_to_aux_cache (struct stat64 *stat_buf, int flags,
-		  unsigned int osversion, const char *soname)
+		  unsigned int osversion, unsigned int isa_level,
+		  const char *soname)
 {
   struct aux_cache_entry_id id;
   id.ino = (uint64_t) stat_buf->st_ino;
   id.ctime = (uint64_t) stat_buf->st_ctime;
   id.size = (uint64_t) stat_buf->st_size;
   id.dev = (uint64_t) stat_buf->st_dev;
-  insert_to_aux_cache (&id, flags, osversion, soname, 1);
+  insert_to_aux_cache (&id, flags, osversion, isa_level, soname, 1);
 }
 
 /* Load auxiliary cache to search for unchanged entries.   */
@@ -1026,6 +1048,7 @@ load_aux_cache (const char *aux_cache_name)
     insert_to_aux_cache (&aux_cache->libs[i].id,
 			 aux_cache->libs[i].flags,
 			 aux_cache->libs[i].osversion,
+			 aux_cache->libs[i].isa_level,
 			 aux_cache->libs[i].soname == 0
 			 ? NULL : aux_cache_data + aux_cache->libs[i].soname,
 			 0);
@@ -1094,7 +1117,7 @@ save_aux_cache (const char *aux_cache_name)
 	      str_offset += len;
 	    }
 	  file_entries->libs[idx].osversion = entry->osversion;
-	  file_entries->libs[idx++].pad = 0;
+	  file_entries->libs[idx++].isa_level = entry->isa_level;
 	}
 
   /* Write out auxiliary cache file.  */
diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 935e3a60b4..32f3bef5ea 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -25,6 +25,7 @@
 #include <stdint.h>
 #include <_itoa.h>
 #include <dl-hwcaps.h>
+#include <dl-isa-level.h>
 
 #ifndef _DL_PLATFORMS_COUNT
 # define _DL_PLATFORMS_COUNT 0
@@ -284,6 +285,9 @@ search_cache (const char *string_table, uint32_t string_table_size,
 
 #ifdef SHARED
 			  named_hwcap = dl_cache_hwcap_extension (libnew);
+			  if (named_hwcap
+			      && !dl_cache_hwcap_isa_level_compatible (libnew))
+			    continue;
 #endif
 
 			  /* The entries with named/extension hwcaps
diff --git a/elf/ldconfig.c b/elf/ldconfig.c
index bbcf8f5c5c..28ed637a29 100644
--- a/elf/ldconfig.c
+++ b/elf/ldconfig.c
@@ -655,6 +655,7 @@ manual_link (char *library)
   struct stat64 stat_buf;
   int flag;
   unsigned int osversion;
+  unsigned int isa_level;
 
   /* Prepare arguments for create_links call.  Split library name in
      directory and filename first.  Since path is allocated, we've got
@@ -721,7 +722,7 @@ manual_link (char *library)
     }
 
   if (process_file (real_library, library, libname, &flag, &osversion,
-		    &soname, 0, &stat_buf))
+		    &isa_level, &soname, 0, &stat_buf))
     {
       error (0, 0, _("No link created since soname could not be found for %s"),
 	     library);
@@ -768,6 +769,7 @@ struct dlib_entry
   int flag;
   int is_link;
   unsigned int osversion;
+  unsigned int isa_level;
   struct dlib_entry *next;
 };
 
@@ -980,17 +982,21 @@ search_dir (const struct dir_entry *entry)
 	 library already and it's not changed.  */
       char *soname;
       unsigned int osversion;
-      if (!search_aux_cache (&lstat_buf, &flag, &osversion, &soname))
+      unsigned int isa_level;
+      if (!search_aux_cache (&lstat_buf, &flag, &osversion, &isa_level,
+			     &soname))
 	{
 	  if (process_file (real_name, file_name, direntry->d_name, &flag,
-			    &osversion, &soname, is_link, &lstat_buf))
+			    &osversion, &isa_level, &soname, is_link,
+			    &lstat_buf))
 	    {
 	      if (real_name != real_file_name)
 		free (real_name);
 	      continue;
 	    }
 	  else if (opt_build_cache)
-	    add_to_aux_cache (&lstat_buf, flag, osversion, soname);
+	    add_to_aux_cache (&lstat_buf, flag, osversion, isa_level,
+			      soname);
 	}
 
       if (soname == NULL)
@@ -1096,6 +1102,7 @@ search_dir (const struct dir_entry *entry)
 		  dlib_ptr->name = xstrdup (direntry->d_name);
 		  dlib_ptr->is_link = is_link;
 		  dlib_ptr->osversion = osversion;
+		  dlib_ptr->isa_level = isa_level;
 		}
 	      /* Don't add this library, abort loop.  */
 	      /* Also free soname, since it's dynamically allocated.  */
@@ -1112,6 +1119,7 @@ search_dir (const struct dir_entry *entry)
 	  dlib_ptr->flag = flag;
 	  dlib_ptr->is_link = is_link;
 	  dlib_ptr->osversion = osversion;
+	  dlib_ptr->isa_level = isa_level;
 	  /* Add at head of list.  */
 	  dlib_ptr->next = dlibs;
 	  dlibs = dlib_ptr;
@@ -1149,7 +1157,7 @@ search_dir (const struct dir_entry *entry)
       if (opt_build_cache)
 	add_to_cache (entry->path, filename, dlib_ptr->soname,
 		      dlib_ptr->flag, dlib_ptr->osversion,
-		      hwcap, entry->hwcaps);
+		      dlib_ptr->isa_level, hwcap, entry->hwcaps);
     }
 
   /* Free all resources.  */
diff --git a/elf/readelflib.c b/elf/readelflib.c
index cdea79d729..c09425a574 100644
--- a/elf/readelflib.c
+++ b/elf/readelflib.c
@@ -17,6 +17,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <elf-read-prop.h>
+
 /* This code is a heavily simplified version of the readelf program
    that's part of the current binutils development version.  For architectures
    which need to handle both 32bit and 64bit ELF libraries,  this file is
@@ -40,8 +42,8 @@ do								\
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   int i;
   unsigned int j;
@@ -86,6 +88,9 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
      libc5/libc6.  */
   *flag = FLAG_ELF;
 
+  /* The default ISA level is 0.  */
+  *isa_level = 0;
+
   dynamic_addr = 0;
   dynamic_size = 0;
   program_interpreter = NULL;
@@ -164,6 +169,78 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
 	    }
 	  break;
 
+	case PT_GNU_PROPERTY:
+	  /* The NT_GNU_PROPERTY_TYPE_0 note must be aligned to 4 bytes
+	     in 32-bit objects and to 8 bytes in 64-bit objects.  Skip
+	     notes with incorrect alignment.  */
+	  if (segment->p_align == (__ELF_NATIVE_CLASS / 8))
+	    {
+	      const ElfW(Nhdr) *note = (const void *) (file_contents
+						       + segment->p_offset);
+	      const ElfW(Addr) size = segment->p_filesz;
+	      const ElfW(Addr) align = segment->p_align;
+
+	      const ElfW(Addr) start = (ElfW(Addr)) (uintptr_t) note;
+	      unsigned int last_type = 0;
+
+	      while ((ElfW(Addr)) (uintptr_t) (note + 1) - start < size)
+		{
+		  /* Find the NT_GNU_PROPERTY_TYPE_0 note.  */
+		  if (note->n_namesz == 4
+		      && note->n_type == NT_GNU_PROPERTY_TYPE_0
+		      && memcmp (note + 1, "GNU", 4) == 0)
+		    {
+		      /* Check for invalid property.  */
+		      if (note->n_descsz < 8
+			  || (note->n_descsz % sizeof (ElfW(Addr))) != 0)
+			goto done;
+
+		      /* Start and end of property array.  */
+		      unsigned char *ptr = (unsigned char *) (note + 1) + 4;
+		      unsigned char *ptr_end = ptr + note->n_descsz;
+
+		      do
+			{
+			  unsigned int type = *(unsigned int *) ptr;
+			  unsigned int datasz = *(unsigned int *) (ptr + 4);
+
+			  /* Property type must be in ascending order.  */
+			  if (type < last_type)
+			    goto done;
+
+			  ptr += 8;
+			  if ((ptr + datasz) > ptr_end)
+			    goto done;
+
+			  last_type = type;
+
+			  /* Target specific property processing.
+			     Return value:
+			       false: Continue processing the properties.
+			       true : Stop processing the properties.
+			   */
+			  if (read_gnu_property (isa_level, type,
+						 datasz, ptr))
+			    goto done;
+
+			  /* Check the next property item.  */
+			  ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
+			}
+		      while ((ptr_end - ptr) >= 8);
+
+		      /* Only handle one NT_GNU_PROPERTY_TYPE_0.  */
+		      goto done;
+		    }
+
+		  note = ((const void *) note
+			  + ELF_NOTE_NEXT_OFFSET (note->n_namesz,
+						  note->n_descsz,
+						  align));
+		}
+	    }
+done:
+	  break;
+
 	default:
 	  break;
 	}
diff --git a/elf/readlib.c b/elf/readlib.c
index 3d52c9a980..7383c23249 100644
--- a/elf/readlib.c
+++ b/elf/readlib.c
@@ -75,7 +75,8 @@ is_gdb_python_file (const char *name)
 int
 process_file (const char *real_file_name, const char *file_name,
 	      const char *lib, int *flag, unsigned int *osversion,
-	      char **soname, int is_link, struct stat64 *stat_buf)
+	      unsigned int *isa_level, char **soname, int is_link,
+	      struct stat64 *stat_buf)
 {
   FILE *file;
   struct stat64 statbuf;
@@ -173,8 +174,8 @@ process_file (const char *real_file_name, const char *file_name,
   /* Libraries have to be shared object files.  */
   else if (elf_header->e_type != ET_DYN)
     ret = 1;
-  else if (process_elf_file (file_name, lib, flag, osversion, soname,
-			     file_contents, statbuf.st_size))
+  else if (process_elf_file (file_name, lib, flag, osversion, isa_level,
+			     soname, file_contents, statbuf.st_size))
     ret = 1;
 
  done:
diff --git a/elf/tst-glibc-hwcaps-2-cache.c b/elf/tst-glibc-hwcaps-2-cache.c
new file mode 100644
index 0000000000..97d9835ddb
--- /dev/null
+++ b/elf/tst-glibc-hwcaps-2-cache.c
@@ -0,0 +1,45 @@
+/* Wrapper to invoke tst-glibc-hwcaps-2 in a container to test ldconfig.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* This program is just a wrapper that runs ldconfig followed by
+   tst-glibc-hwcaps-2.  The actual test is provided via an
+   implementation in a sysdeps subdirectory.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <support/support.h>
+#include <support/capture_subprocess.h>
+
+int
+main (int argc, char **argv)
+{
+  /* Run ldconfig to populate the cache.  */
+  char *command = xasprintf ("%s/ldconfig", support_install_rootsbindir);
+  struct support_capture_subprocess result =
+    support_capture_subprogram (command,  &((char *) { NULL }));
+  support_capture_subprocess_check (&result, "ldconfig", 0, sc_allow_none);
+  free (command);
+
+  /* Reuse tst-glibc-hwcaps.  Since this code is running in a
+     container, we can launch it directly.  */
+  char *path = xasprintf ("%s/elf/tst-glibc-hwcaps-2", support_objdir_root);
+  execv (path, argv);
+  printf ("error: execv of %s failed: %m\n", path);
+  return 1;
+}
diff --git a/elf/tst-glibc-hwcaps-2-cache.root/etc/ld.so.conf b/elf/tst-glibc-hwcaps-2-cache.root/etc/ld.so.conf
new file mode 100644
index 0000000000..e1e74dbda2
--- /dev/null
+++ b/elf/tst-glibc-hwcaps-2-cache.root/etc/ld.so.conf
@@ -0,0 +1,2 @@
+# This file was created to suppress a warning from ldconfig:
+# /sbin/ldconfig: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf: No such file or directory
diff --git a/elf/tst-glibc-hwcaps-2-cache.root/postclean.req b/elf/tst-glibc-hwcaps-2-cache.root/postclean.req
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/elf/tst-glibc-hwcaps-2-cache.script b/elf/tst-glibc-hwcaps-2-cache.script
new file mode 100644
index 0000000000..8e4e9896ee
--- /dev/null
+++ b/elf/tst-glibc-hwcaps-2-cache.script
@@ -0,0 +1,8 @@
+# test-container does not support scripts in sysdeps directories, so
+# collect everything in one file.
+
+mkdirp 0770 $L/glibc-hwcaps/x86-64-v2
+mkdirp 0770 $L/glibc-hwcaps/x86-64-v3
+cp $B/elf/libx86-64-isa-level-1.so $L/libx86-64-isa-level.so
+cp $B/elf/libx86-64-isa-level-3.so $L/glibc-hwcaps/x86-64-v2/libx86-64-isa-level.so
+cp $B/elf/libx86-64-isa-level-4.so $L/glibc-hwcaps/x86-64-v3/libx86-64-isa-level.so
diff --git a/sysdeps/generic/dl-cache.h b/sysdeps/generic/dl-cache.h
index c7eca70d0c..964d50a486 100644
--- a/sysdeps/generic/dl-cache.h
+++ b/sysdeps/generic/dl-cache.h
@@ -106,14 +106,24 @@ struct file_entry_new
    entries.  */
 #define DL_CACHE_HWCAP_EXTENSION (1ULL << 62)
 
+/* The number of the ISA level bits in the upper 32 bits of the hwcap
+   field.  */
+#define DL_CACHE_HWCAP_ISA_LEVEL_COUNT 10
+
+/* The mask of the ISA level bits in the hwcap field.  */
+#define DL_CACHE_HWCAP_ISA_LEVEL_MASK \
+  ((1 << DL_CACHE_HWCAP_ISA_LEVEL_COUNT) -1)
+
 /* Return true if the ENTRY->hwcap value indicates that
    DL_CACHE_HWCAP_EXTENSION is used.  */
 static inline bool
 dl_cache_hwcap_extension (struct file_entry_new *entry)
 {
-  /* If DL_CACHE_HWCAP_EXTENSION is set, but other bits as well, this
-     is a different kind of extension.  */
-  return (entry->hwcap >> 32) == (DL_CACHE_HWCAP_EXTENSION >> 32);
+  /* This is an hwcap extension if only the DL_CACHE_HWCAP_EXTENSION bit
+     is set, ignoring the lower 32 bits as well as the ISA level bits in
+     the upper 32 bits.  */
+  return (((entry->hwcap >> 32) & ~DL_CACHE_HWCAP_ISA_LEVEL_MASK)
+	  == (DL_CACHE_HWCAP_EXTENSION >> 32));
 }
 
 /* See flags member of struct cache_file_new below.  */
diff --git a/sysdeps/generic/dl-isa-level.h b/sysdeps/generic/dl-isa-level.h
new file mode 100644
index 0000000000..6fcd319c49
--- /dev/null
+++ b/sysdeps/generic/dl-isa-level.h
@@ -0,0 +1,25 @@
+/* Support for reading ISA level in /etc/ld.so.cache files written by
+   Linux ldconfig.  Generic version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* Return true if the ISA level in ENTRY is compatible with CPU.  */
+static inline bool
+dl_cache_hwcap_isa_level_compatible (struct file_entry_new *entry)
+{
+  return true;
+}
diff --git a/sysdeps/generic/elf-read-prop.h b/sysdeps/generic/elf-read-prop.h
new file mode 100644
index 0000000000..98c3d2acb5
--- /dev/null
+++ b/sysdeps/generic/elf-read-prop.h
@@ -0,0 +1,34 @@
+/* Support for GNU properties in ldconfig.  Generic version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _ELF_READ_PROP_H
+#define _ELF_READ_PROP_H
+
+/* Called for each property in the NT_GNU_PROPERTY_TYPE_0 note of SEGMENT.
+   Return value:
+     false: Continue processing the properties.
+     true : Stop processing the properties.
+ */
+static inline bool __attribute__ ((always_inline))
+read_gnu_property (unsigned int *isal_level, uint32_t type, uint32_t
+		   datasz, void *data)
+{
+  return true;
+}
+
+#endif
diff --git a/sysdeps/generic/ldconfig.h b/sysdeps/generic/ldconfig.h
index eb070fd259..3ab757077d 100644
--- a/sysdeps/generic/ldconfig.h
+++ b/sysdeps/generic/ldconfig.h
@@ -70,8 +70,9 @@ const char *glibc_hwcaps_subdirectory_name
   (const struct glibc_hwcaps_subdirectory *);
 
 extern void add_to_cache (const char *path, const char *filename,
-			  const char *soname,
-			  int flags, unsigned int osversion, uint64_t hwcap,
+			  const char *soname, int flags,
+			  unsigned int osversion, unsigned int isa_level,
+			  uint64_t hwcap,
 			  struct glibc_hwcaps_subdirectory *);
 
 extern void init_aux_cache (void);
@@ -79,23 +80,28 @@ extern void init_aux_cache (void);
 extern void load_aux_cache (const char *aux_cache_name);
 
 extern int search_aux_cache (struct stat64 *stat_buf, int *flags,
-			     unsigned int *osversion, char **soname);
+			     unsigned int *osversion,
+			     unsigned int *isa_level, char **soname);
 
 extern void add_to_aux_cache (struct stat64 *stat_buf, int flags,
-			      unsigned int osversion, const char *soname);
+			      unsigned int osversion,
+			      unsigned int isa_level, const char *soname);
 
 extern void save_aux_cache (const char *aux_cache_name);
 
 /* Declared in readlib.c.  */
 extern int process_file (const char *real_file_name, const char *file_name,
-			 const char *lib, int *flag, unsigned int *osversion,
-			 char **soname, int is_link, struct stat64 *stat_buf);
+			 const char *lib, int *flag,
+			 unsigned int *osversion, unsigned int *isa_level,
+			 char **soname, int is_link,
+			 struct stat64 *stat_buf);
 
 extern char *implicit_soname (const char *lib, int flag);
 
 /* Declared in readelflib.c.  */
-extern int process_elf_file (const char *file_name, const char *lib, int *flag,
-			     unsigned int *osversion, char **soname,
+extern int process_elf_file (const char *file_name, const char *lib,
+			     int *flag, unsigned int *osversion,
+			     unsigned int *isa_level, char **soname,
 			     void *file_contents, size_t file_length);
 
 /* Declared in chroot_canon.c.  */
diff --git a/sysdeps/unix/sysv/linux/arm/readelflib.c b/sysdeps/unix/sysv/linux/arm/readelflib.c
index 2d3ecb1eef..ade2f49aeb 100644
--- a/sysdeps/unix/sysv/linux/arm/readelflib.c
+++ b/sysdeps/unix/sysv/linux/arm/readelflib.c
@@ -18,18 +18,20 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret;
@@ -38,8 +40,8 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
     {
       Elf32_Ehdr *elf32_header = (Elf32_Ehdr *) elf_header;
 
-      ret = process_elf32_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf32_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
 
       if (!ret && EF_ARM_EABI_VERSION (elf32_header->e_flags) == EF_ARM_EABI_VER5)
 	{
@@ -57,8 +59,8 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
     }
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* AArch64 libraries are always libc.so.6+.  */
       if (!ret)
 	*flag = FLAG_AARCH64_LIB64|FLAG_ELF_LIBC6;
diff --git a/sysdeps/unix/sysv/linux/ia64/readelflib.c b/sysdeps/unix/sysv/linux/ia64/readelflib.c
index 7fb3ace359..2aa32666aa 100644
--- a/sysdeps/unix/sysv/linux/ia64/readelflib.c
+++ b/sysdeps/unix/sysv/linux/ia64/readelflib.c
@@ -16,29 +16,31 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname,
-		  void *file_contents, size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret;
 
   if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
-    return process_elf32_file (file_name, lib, flag, osversion, soname,
-			       file_contents, file_length);
+    return process_elf32_file (file_name, lib, flag, osversion, isa_level,
+			       soname, file_contents, file_length);
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* Intel 64bit libraries are always libc.so.6+.  */
       if (!ret)
 	*flag = FLAG_IA64_LIB64|FLAG_ELF_LIBC6;
diff --git a/sysdeps/unix/sysv/linux/mips/readelflib.c b/sysdeps/unix/sysv/linux/mips/readelflib.c
index e50bc3ce23..d0e809d893 100644
--- a/sysdeps/unix/sysv/linux/mips/readelflib.c
+++ b/sysdeps/unix/sysv/linux/mips/readelflib.c
@@ -20,18 +20,20 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   union
     {
@@ -45,8 +47,8 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
   elf_header.eh = file_contents;
   if (elf_header.eh->e_ident [EI_CLASS] == ELFCLASS32)
     {
-      ret = process_elf32_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf32_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       if (!ret)
 	{
 	  Elf32_Word flags = elf_header.eh32->e_flags;
@@ -62,8 +64,8 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
     }
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* n64 libraries are always libc.so.6+.  */
       if (!ret)
 	{
diff --git a/sysdeps/unix/sysv/linux/powerpc/readelflib.c b/sysdeps/unix/sysv/linux/powerpc/readelflib.c
index 4f9a9be254..51f8a9496a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/readelflib.c
+++ b/sysdeps/unix/sysv/linux/powerpc/readelflib.c
@@ -17,29 +17,31 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret;
 
   if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
-    return process_elf32_file (file_name, lib, flag, osversion, soname,
-			       file_contents, file_length);
+    return process_elf32_file (file_name, lib, flag, osversion, isa_level,
+			       soname, file_contents, file_length);
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* PowerPC 64bit libraries are always libc.so.6+.  */
       if (!ret)
 	*flag = FLAG_POWERPC_LIB64|FLAG_ELF_LIBC6;
diff --git a/sysdeps/unix/sysv/linux/riscv/readelflib.c b/sysdeps/unix/sysv/linux/riscv/readelflib.c
index 2aca6670a8..3822d63a05 100644
--- a/sysdeps/unix/sysv/linux/riscv/readelflib.c
+++ b/sysdeps/unix/sysv/linux/riscv/readelflib.c
@@ -17,11 +17,13 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* The ELF flags supported by our current glibc port:
@@ -38,8 +40,8 @@ int process_elf64_file (const char *file_name, const char *lib, int *flag,
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   Elf32_Ehdr *elf32_header = (Elf32_Ehdr *) elf_header;
@@ -52,14 +54,14 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
 
   if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
     {
-      ret = process_elf32_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf32_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       flags = elf32_header->e_flags;
     }
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       flags = elf64_header->e_flags;
     }
 
diff --git a/sysdeps/unix/sysv/linux/s390/readelflib.c b/sysdeps/unix/sysv/linux/s390/readelflib.c
index fc21af34d8..e190109e3d 100644
--- a/sysdeps/unix/sysv/linux/s390/readelflib.c
+++ b/sysdeps/unix/sysv/linux/s390/readelflib.c
@@ -16,29 +16,31 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret;
 
   if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
-    return process_elf32_file (file_name, lib, flag, osversion, soname,
-			       file_contents, file_length);
+    return process_elf32_file (file_name, lib, flag, osversion, isa_level,
+			       soname, file_contents, file_length);
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* S/390 64bit libraries are always libc.so.6+.  */
       if (!ret)
 	*flag = FLAG_S390_LIB64|FLAG_ELF_LIBC6;
diff --git a/sysdeps/unix/sysv/linux/sparc/readelflib.c b/sysdeps/unix/sysv/linux/sparc/readelflib.c
index d54b8dfd28..bbfc81337a 100644
--- a/sysdeps/unix/sysv/linux/sparc/readelflib.c
+++ b/sysdeps/unix/sysv/linux/sparc/readelflib.c
@@ -18,29 +18,31 @@
    <https://www.gnu.org/licenses/>.  */
 
 
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret;
 
   if (elf_header->e_ident [EI_CLASS] == ELFCLASS32)
-    return process_elf32_file (file_name, lib, flag, osversion, soname,
-			       file_contents, file_length);
+    return process_elf32_file (file_name, lib, flag, osversion, isa_level,
+			       soname, file_contents, file_length);
   else
     {
-      ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-				file_contents, file_length);
+      ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+				soname, file_contents, file_length);
       /* Sparc 64bit libraries are always libc.so.6+.  */
       if (!ret)
 	*flag = FLAG_SPARC_LIB64|FLAG_ELF_LIBC6;
diff --git a/sysdeps/unix/sysv/linux/x86/elf-read-prop.h b/sysdeps/unix/sysv/linux/x86/elf-read-prop.h
new file mode 100644
index 0000000000..85affa2864
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/elf-read-prop.h
@@ -0,0 +1,60 @@
+/* Support for GNU properties in ldconfig.  x86 version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _ELF_READ_PROP_H
+#define _ELF_READ_PROP_H
+
+#include <dl-cache.h>
+
+/* Called for each property in the NT_GNU_PROPERTY_TYPE_0 note of SEGMENT.
+   Return value:
+     false: Continue processing the properties.
+     true : Stop processing the properties.
+ */
+static inline bool __attribute__ ((always_inline))
+read_gnu_property (unsigned int *isal_level, uint32_t type,
+		   uint32_t datasz, void *data)
+{
+  /* Property type must be in ascending order.  */
+  if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
+    return true;
+
+  if (type == GNU_PROPERTY_X86_ISA_1_NEEDED)
+    {
+      if (datasz == 4)
+	{
+	  /* The size of GNU_PROPERTY_X86_ISA_1_NEEDED must be 4 bytes.
+	     There is no point to continue if this type is ill-formed.  */
+	  unsigned int isa_1_needed = *(unsigned int *) data;
+	  _Static_assert (((sizeof (isa_1_needed) * 8)
+			   <= (1 << DL_CACHE_HWCAP_ISA_LEVEL_COUNT)),
+			  "DL_CACHE_HWCAP_ISA_LEVEL_COUNT is too small");
+	  if (isa_1_needed != 0)
+	    {
+	      unsigned int level;
+	      asm ("bsr %1, %0" : "=r" (level) : "g" (isa_1_needed));
+	      *isal_level = level;
+	    }
+	}
+      return true;
+    }
+
+  return false;
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/x86/readelflib.c b/sysdeps/unix/sysv/linux/x86/readelflib.c
index a4df70e7e6..4a9bcc82cb 100644
--- a/sysdeps/unix/sysv/linux/x86/readelflib.c
+++ b/sysdeps/unix/sysv/linux/x86/readelflib.c
@@ -17,19 +17,20 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-
-int process_elf32_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf32_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
-int process_elf64_file (const char *file_name, const char *lib, int *flag,
-			unsigned int *osversion, char **soname,
+int process_elf64_file (const char *file_name, const char *lib,
+			int *flag, unsigned int *osversion,
+			unsigned int *isa_level, char **soname,
 			void *file_contents, size_t file_length);
 
 /* Returns 0 if everything is ok, != 0 in case of error.  */
 int
 process_elf_file (const char *file_name, const char *lib, int *flag,
-		  unsigned int *osversion, char **soname, void *file_contents,
-		  size_t file_length)
+		  unsigned int *osversion, unsigned int *isa_level,
+		  char **soname, void *file_contents, size_t file_length)
 {
   ElfW(Ehdr) *elf_header = (ElfW(Ehdr) *) file_contents;
   int ret, file_flag = 0;
@@ -68,11 +69,11 @@ failed:
     }
 
   if (elf_header->e_ident[EI_CLASS] == ELFCLASS32)
-    ret = process_elf32_file (file_name, lib, flag, osversion, soname,
-			      file_contents, file_length);
+    ret = process_elf32_file (file_name, lib, flag, osversion, isa_level,
+			      soname, file_contents, file_length);
   else
-    ret = process_elf64_file (file_name, lib, flag, osversion, soname,
-			      file_contents, file_length);
+    ret = process_elf64_file (file_name, lib, flag, osversion, isa_level,
+			      soname, file_contents, file_length);
 
   if (!ret && file_flag)
     *flag = file_flag;
diff --git a/sysdeps/unix/sysv/linux/x86_64/Makefile b/sysdeps/unix/sysv/linux/x86_64/Makefile
index 9b82155393..5e19202ebf 100644
--- a/sysdeps/unix/sysv/linux/x86_64/Makefile
+++ b/sysdeps/unix/sysv/linux/x86_64/Makefile
@@ -13,3 +13,54 @@ endif
 ifeq ($(subdir),misc)
 gen-as-const-headers += sigaltstack-offsets.sym
 endif
+
+ifeq ($(subdir),elf)
+ifeq (yes,$(enable-x86-isa-level))
+tests += \
+  tst-glibc-hwcaps-2
+ifeq (no,$(build-hardcoded-path-in-tests))
+# This is an ld.so.cache test, and RPATH/RUNPATH in the executable
+# interferes with its test objectives.
+tests-container += \
+  tst-glibc-hwcaps-2-cache
+endif
+modules-names += \
+  libx86-64-isa-level-1 \
+  libx86-64-isa-level-2 \
+  libx86-64-isa-level-3 \
+  libx86-64-isa-level-4
+
+$(objpfx)tst-glibc-hwcaps-2: $(objpfx)libx86-64-isa-level.so
+
+$(objpfx)tst-glibc-hwcaps-2.out: \
+  $(objpfx)glibc-hwcaps/x86-64-v2/libx86-64-isa-level.so \
+  $(objpfx)glibc-hwcaps/x86-64-v4/libx86-64-isa-level.so \
+  $(objpfx)glibc-hwcaps/x86-64-v3/libx86-64-isa-level.so
+$(objpfx)glibc-hwcaps/x86-64-v2/libx86-64-isa-level.so: \
+  $(objpfx)libx86-64-isa-level-2.so
+	$(make-target-directory)
+	cp $< $@
+$(objpfx)glibc-hwcaps/x86-64-v3/libx86-64-isa-level.so: \
+  $(objpfx)libx86-64-isa-level-3.so
+	$(make-target-directory)
+	cp $< $@
+$(objpfx)glibc-hwcaps/x86-64-v4/libx86-64-isa-level.so: \
+  $(objpfx)libx86-64-isa-level-4.so
+	$(make-target-directory)
+	cp $< $@
+
+CFLAGS-libx86-64-isa-level-1.os += -march=x86-64
+CFLAGS-libx86-64-isa-level-2.os += -march=x86-64
+CFLAGS-libx86-64-isa-level-3.os += -march=x86-64
+CFLAGS-libx86-64-isa-level-4.os += -march=x86-64
+
+# The test modules are parameterized by preprocessor macros.
+LDFLAGS-libx86-64-isa-level-1.so += -Wl,-soname,libx86-64-isa-level.so
+LDFLAGS-libx86-64-isa-level-4.so += -Wl,-soname,libx86-64-isa-level.so
+$(objpfx)libx86-64-isa-level%.os: $(..)/sysdeps/unix/sysv/linux/x86_64/x86-64-isa-level-VALUE.c
+	$(compile-command.c) -DVALUE=$(lastword $(subst -, ,$*)) \
+	  -DISA_LEVEL="(1 << ($(lastword $(subst -, ,$*)) - 1))"
+$(objpfx)libx86-64-isa-level.so: $(objpfx)libx86-64-isa-level-1.so
+	cp $< $@
+endif
+endif # $(subdir) == elf
diff --git a/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c b/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c
new file mode 100644
index 0000000000..fe91bfd224
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/tst-glibc-hwcaps-2.c
@@ -0,0 +1,84 @@
+/* Check ISA level on shared object in glibc-hwcaps subdirectories.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <elf.h>
+#include <get-isa-level.h>
+#include <support/check.h>
+#include <support/test-driver.h>
+
+extern int dso_isa_level (void);
+
+static int
+do_test (void)
+{
+  const struct cpu_features *cpu_features
+    = __x86_get_cpu_features (COMMON_CPUID_INDEX_MAX);
+  unsigned int isa_level = get_isa_level (cpu_features);
+  bool has_isa_baseline = ((isa_level & GNU_PROPERTY_X86_ISA_1_BASELINE)
+			   == GNU_PROPERTY_X86_ISA_1_BASELINE);
+  bool has_isa_v2 = ((isa_level & GNU_PROPERTY_X86_ISA_1_V2)
+			   == GNU_PROPERTY_X86_ISA_1_V2);
+  bool has_isa_v3 = ((isa_level & GNU_PROPERTY_X86_ISA_1_V3)
+			   == GNU_PROPERTY_X86_ISA_1_V3);
+  bool has_isa_v4 = ((isa_level & GNU_PROPERTY_X86_ISA_1_V4)
+			   == GNU_PROPERTY_X86_ISA_1_V4);
+
+  if (!has_isa_baseline)
+    return EXIT_FAILURE;
+
+  int level = dso_isa_level ();
+  int ret;
+  switch (level)
+    {
+    case 1:
+    case 2:
+      /* The default libx86-64-isa-level.so is used.  */
+      printf ("The default shared library is used.\n");
+      if (has_isa_v3 || has_isa_v4 || !has_isa_v2)
+	ret = EXIT_FAILURE;
+      else
+	ret = EXIT_SUCCESS;
+      break;
+    case 3:
+      /* libx86-64-isa-level.so marked as x86-64 ISA level 3 needed in
+	 x86-64-v2 should be ignored on lesser CPU.  */
+      printf ("x86-64 ISA level 3 shared library is used.\n");
+      if (has_isa_v4 || !has_isa_v3)
+	ret = EXIT_FAILURE;
+      else
+	ret = EXIT_SUCCESS;
+      break;
+    case 4:
+      /* libx86-64-isa-level.so marked as x86-64 ISA level 4 needed in
+	 x86-64-v3 should be ignored on lesser CPU.  */
+      printf ("x86-64 ISA level 4 shared library is used.\n");
+      if (has_isa_v4)
+	ret = EXIT_SUCCESS;
+      else
+	ret = EXIT_FAILURE;
+      break;
+    default:
+      abort ();
+    }
+  return ret;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/x86-64-isa-level-VALUE.c b/sysdeps/unix/sysv/linux/x86_64/x86-64-isa-level-VALUE.c
new file mode 100644
index 0000000000..2813d627cc
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/x86-64-isa-level-VALUE.c
@@ -0,0 +1,4 @@
+#define INCLUDE_X86_ISA_LEVEL
+#define MARKER dso_isa_level
+#include <isa-level.c>
+#include <markermodMARKER-VALUE.c>
diff --git a/sysdeps/x86/dl-isa-level.h b/sysdeps/x86/dl-isa-level.h
new file mode 100644
index 0000000000..afe390c365
--- /dev/null
+++ b/sysdeps/x86/dl-isa-level.h
@@ -0,0 +1,31 @@
+/* Support for reading ISA level in /etc/ld.so.cache files written by
+   Linux ldconfig.  x86 version.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/platform/x86.h>
+
+/* Return true if the ISA level in ENTRY is compatible with CPU.  */
+static inline bool
+dl_cache_hwcap_isa_level_compatible (struct file_entry_new *entry)
+{
+  const struct cpu_features *cpu_features = __get_cpu_features ();
+  unsigned int isa_level
+    = 1 << ((entry->hwcap >> 32) & DL_CACHE_HWCAP_ISA_LEVEL_MASK);
+
+  return (isa_level & cpu_features->isa_1) == isa_level;
+}