diff --git a/tools/tools/git/git-arc.sh b/tools/tools/git/git-arc.sh
--- a/tools/tools/git/git-arc.sh
+++ b/tools/tools/git/git-arc.sh
@@ -51,7 +51,7 @@
 Commands:
   create [-l] [-r <reviewer1>[,<reviewer2>...]] [-s subscriber[,...]] [<commit>|<commit range>]
   list <commit>|<commit range>
-  patch <diff1> [<diff2> ...]
+  patch -c <diff1> [<diff2> ...]
   stage [-b branch] [<commit>|<commit range>]
   update [-m message] [<commit>|<commit range>]
 
@@ -133,6 +133,11 @@
 
   $ git arc patch D12345
 
+  Apply the patch in review D12345 to the currently checked-out tree, and
+  commit it using the review's title, summary and author
+
+  $ git arc patch -c D12345
+
   List the status of reviews for all the commits in the branch "feature":
 
   $ git arc list main..feature
@@ -455,18 +460,150 @@
     done
 }
 
+gitarc_default_email()
+{
+    local addr name
+
+    addr=$1
+    name=$2
+    printf "%s <%s>\n" "${name}" $(echo "$addr" | sed -e 's/\(.*\)_/\1@/')
+}
+
+# Try to guess our way to a good author name. The DWIM is strong in this
+# function, but these hueristics seem to generally produce the right results, in
+# the sample of src commits I checked out.
+gitarc_find_author()
+{
+    local addr name email
+
+    addr="$1"
+    name="$2"
+
+    # The lovely and almost, but really really annoyingly not quite, phab
+    # interface gives us almost enough data to create an author, but sadly not
+    # quite. So we play whack-a-mole with heuristics to come up with something
+    # one hopefully calls 'a sane set of defaults'.
+
+    # Choice 1: It's a FreeBSD commiter. These folks have no '.' in their
+    # phab username/addr
+    case "$addr" in
+	*.*) ;;		# external user
+	*)
+	    echo "$name <$addr@FreeBSD.org>"
+	    return
+	    ;;
+    esac
+
+    # Choice 2: We know this user. They've committed before, and they happened
+    # to use an email that's somewhat similar to their phab username.
+    email=$(git log -1 --author "$(echo $addr | tr _ .)" --pretty="%aN <%aE>")
+    if [ -n "$email" ]; then
+	echo "$email"
+	return
+    fi
+
+    # Choice 3: We know this user. They've committed before, and they happened
+    # to use the same name, unless the name has the word 'user' in it. This
+    # might not be a good idea, since names can be somewhat common (there
+    # are two Andrew Turners that have contributed to FreeBSD, for example).
+    if (echo "${name}" | grep -w "[Uu]ser" -q); then
+    else
+	email=$(git log -1 --author "${name}" --pretty="%aN <%aE>")
+	if [ -n "$email" ]; then
+	    echo "$email"
+	    return
+	fi
+    fi
+
+    # Choice 4: Wing it as best we can. In this scenario, we replace the last _
+    # with a @, and call it the email address...
+    # Annoying fun fact: Phab replaces all non alpha-numerics with _, so we
+    # don't know if the prior _ are _ or + or any number of other characters.
+    # So this winging it isn't always our best hope, but will usually get
+    # things mostly enough right.
+    gitarc_default_email "${addr}" "${name}"
+}
+
+gitarc_commit()
+{
+    local diff reviewid review_data authorid user_data user_addr user_name author
+    local tmp def_email
+
+    diff=$1
+    reviewid=$(diff2phid "$diff")
+    review_data=$(echo '{
+                  "constraints": {"phids": ["'"$reviewid"'"]}
+              }' |
+        arc_call_conduit -- differential.revision.search)
+    authorid=$(echo "$review_data" | jq -r '.response.data[].fields.authorPHID' )
+    user_data=$(echo '{
+                  "constraints": {"phids": ["'"$authorid"'"]},
+                  "attachments": {"revisions": true}
+              }' |
+            arc call-conduit -- user.search | grep -v ^Warning: |
+            jq -r '.response.data[].fields')
+    user_addr=$(echo "$user_data" | jq -r '.username')
+    user_name=$(echo "$user_data" | jq -r '.realName')
+    author=$(gitarc_find_author "$user_addr" "$user_name")
+
+    tmp=$(mktemp)
+    echo "$review_data" | jq -r '.response.data[].fields.title' > $tmp
+    echo >> $tmp
+    echo "$review_data" | jq -r '.response.data[].fields.summary' >> $tmp
+    echo >> $tmp
+    # XXX this leaves an extra newline in some cases.
+    reviewers=$(diff2reviewers "$diff" | sed '/^$/d' | paste -sd ',' - | sed 's/,/, /g')
+    if [ -n "$reviewers" ]; then
+        printf "Reviewed by:\t%s\n" "${reviewers}" >> "$tmp"
+    fi
+    printf "Differential Revision:\thttps://reviews.freebsd.org/%s\n" "${diff}" >> "$tmp"
+    git commit --author "${author}" --file "$tmp"
+    rm "$tmp"
+
+    # When Phabricator creates accounts, it does so by replacing all special
+    # characters with _, which is many-to-1, which cannot be undone. This is
+    # rare enough, though that we just warn about the condition for manual
+    # intervention. We try to make our best guess, but for first time submitters
+    # there's no data to correlate against. Eg, we don't know if a_b_c.com is
+    # a_b@c.com or a+b@c.com.
+    def_email=$(gitarc_default_email "${user_addr}" "${user_name}")
+    if [ "${author}" = "${def_email}" ]; then
+	case "${author}" in
+	    *_*)
+		warn "Guessed '${author}' has '_' might be wrong, double check."
+		;;
+	esac
+    fi
+}
+
 gitarc__patch()
 {
-    local rev
+    local rev commit
 
     if [ $# -eq 0 ]; then
         err_usage
     fi
 
+    commit=false
+    while getopts c o; do
+        case "$o" in
+        c)
+            commit=true
+            ;;
+        *)
+            err_usage
+            ;;
+        esac
+    done
+    shift $((OPTIND-1))
+
     for rev in "$@"; do
         arc patch --skip-dependencies --nocommit --nobranch --force "$rev"
         echo "Applying ${rev}..."
         [ $? -eq 0 ] || break
+	if $commit; then
+	    gitarc_commit $rev
+	fi
     done
 }