diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index bbc2710..cf575dc 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -7729,6 +7729,12 @@ If you combine this flag with the @address@hidden operand,
 you should also specify @samp{conv=notrunc} unless you want the
 output file to be truncated before being appended to.
 
address@hidden cio
address@hidden cio
address@hidden concurrent I/O (AIX)
+Use JFS2 concurrent I/O for data.  This is an option specific
+to JFS2 filesystems on the AIX operating system.
+
 @item direct
 @opindex direct
 @cindex direct I/O
diff --git a/src/dd.c b/src/dd.c
index e54cc14..37c55e8 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -288,6 +288,7 @@ static struct symbol_value const flags[] =
 {
   {"append",	O_APPEND},
   {"binary",	O_BINARY},
+  {"cio",	O_CIO},
   {"direct",	O_DIRECT},
   {"directory",	O_DIRECTORY},
   {"dsync",	O_DSYNC},
@@ -508,6 +509,8 @@ Each FLAG symbol may be:\n\
 \n\
   append    append mode (makes sense only for output; conv=notrunc suggested)\n\
 "), stdout);
+      if (O_CIO)
+	fputs (_("  cio       use JFS2 concurrent I/O for data\n"), stdout);
       if (O_DIRECT)
 	fputs (_("  direct    use direct I/O for data\n"), stdout);
       if (O_DIRECTORY)