diff --git a/llvm/docs/Phabricator.rst b/llvm/docs/Phabricator.rst
--- a/llvm/docs/Phabricator.rst
+++ b/llvm/docs/Phabricator.rst
@@ -42,8 +42,7 @@
 .. code-block:: console
 
   % cd arcanist
-  % git fetch https://github.com/rashkov/arcanist update_cacerts
-  % git cherry-pick e3659d43d8911e91739f3b0c5935598bceb859aa
+  % git am <path/to/llvm-project>/llvm/utils/phabricator/*.patch
 
 You can learn more about how to use arc to interact with
 Phabricator in the `Arcanist User Guide`_.
diff --git a/llvm/utils/phabricator/0001-Fix-PHP-8.1-incompatibility-with-arc-patch-D-12345.patch b/llvm/utils/phabricator/0001-Fix-PHP-8.1-incompatibility-with-arc-patch-D-12345.patch
new file mode 100644
--- /dev/null
+++ b/llvm/utils/phabricator/0001-Fix-PHP-8.1-incompatibility-with-arc-patch-D-12345.patch
@@ -0,0 +1,70 @@
+From bb2e9a0394a48f4ef3576e8d91607e8129b2b716 Mon Sep 17 00:00:00 2001
+From: Nick Desaulniers <ndesaulniers@google.com>
+Date: Fri, 8 Jul 2022 14:55:46 -0700
+Subject: [PATCH] Fix PHP 8.1 incompatibility with `arc patch D<12345>`
+
+Fixes the following observed error with PHP 8.1:
+
+  EXCEPTION: (RuntimeException) preg_match(): Passing null to parameter phacility#2 ($subject) of type string is deprecated at [<arcanist>/src/error/PhutilErrorHandler.php:261]
+  arcanist(head=master, ref.master=acec17af414f)
+    #0 PhutilErrorHandler::handleError(integer, string, string, integer)
+    phacility#1 preg_match(string, NULL, NULL) called at [<arcanist>/src/repository/api/ArcanistGitAPI.php:603]
+    phacility#2 ArcanistGitAPI::getCanonicalRevisionName(NULL) called at [<arcanist>/src/repository/api/ArcanistGitAPI.php:1146]
+    phacility#3 ArcanistGitAPI::hasLocalCommit(NULL) called at [<arcanist>/src/workflow/ArcanistPatchWorkflow.php:433]
+    phacility#4 ArcanistPatchWorkflow::run() called at [<arcanist>/src/workflow/ArcanistPatchWorkflow.php:398]
+    phacility#5 ArcanistPatchWorkflow::run() called at [<arcanist>/scripts/arcanist.php:427]
+
+Link: https://secure.phabricator.com/book/phabcontrib/article/contributing_code/
+Link: https://reviews.llvm.org/D129232#3634072
+Suggested-by: Yuanfang Chen <yuanfang.chen@sony.com>
+Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
+---
+ src/differential/ArcanistDifferentialDependencyGraph.php | 3 ++-
+ src/lint/linter/ArcanistScriptAndRegexLinter.php         | 2 +-
+ src/repository/api/ArcanistGitAPI.php                    | 3 ++-
+ 3 files changed, 5 insertions(+), 3 deletions(-)
+
+diff --git a/src/differential/ArcanistDifferentialDependencyGraph.php b/src/differential/ArcanistDifferentialDependencyGraph.php
+index 64e2f9c71c20..fbc4e6594f0e 100644
+--- a/src/differential/ArcanistDifferentialDependencyGraph.php
++++ b/src/differential/ArcanistDifferentialDependencyGraph.php
+@@ -42,7 +42,8 @@ final class ArcanistDifferentialDependencyGraph extends AbstractDirectedGraph {
+     $edges = array();
+     foreach ($dependencies as $dependency) {
+       $dependency_revision = $this->getCommitHashFromDict($dependency);
+-      if ($repository_api->hasLocalCommit($dependency_revision)) {
++      if (phutil_nonempty_string($dependency_revision) &&
++          $repository_api->hasLocalCommit($dependency_revision)) {
+         $edges[$dependency['phid']] = array();
+         continue;
+       }
+diff --git a/src/lint/linter/ArcanistScriptAndRegexLinter.php b/src/lint/linter/ArcanistScriptAndRegexLinter.php
+index 0c3d9d9a11ca..b9f6924ec997 100644
+--- a/src/lint/linter/ArcanistScriptAndRegexLinter.php
++++ b/src/lint/linter/ArcanistScriptAndRegexLinter.php
+@@ -338,7 +338,7 @@ final class ArcanistScriptAndRegexLinter extends ArcanistLinter {
+     }
+ 
+     $line = idx($match, 'line');
+-    if (strlen($line)) {
++    if (phutil_nonempty_string($line) && strlen($line)) {
+       $line = (int)$line;
+       if (!$line) {
+         $line = 1;
+diff --git a/src/repository/api/ArcanistGitAPI.php b/src/repository/api/ArcanistGitAPI.php
+index 6c6d2ac42a19..13907d5634be 100644
+--- a/src/repository/api/ArcanistGitAPI.php
++++ b/src/repository/api/ArcanistGitAPI.php
+@@ -1143,7 +1143,8 @@ final class ArcanistGitAPI extends ArcanistRepositoryAPI {
+ 
+   public function hasLocalCommit($commit) {
+     try {
+-      if (!$this->getCanonicalRevisionName($commit)) {
++      if (!phutil_nonempty_string($commit) ||
++          !$this->getCanonicalRevisionName($commit)) {
+         return false;
+       }
+     } catch (CommandException $exception) {
+-- 
+2.37.0.rc0.161.g10f37bed90-goog
+