diff --git a/src/ghstack/github_utils.py b/src/ghstack/github_utils.py
index aa186b3..7d343d8 100644
--- a/src/ghstack/github_utils.py
+++ b/src/ghstack/github_utils.py
@@ -123,8 +123,19 @@ def get_github_repo_info(
     }
 
 
+# Matches GitHub PR URLs like:
+#   https://github.com/owner/repo/pull/123
+#   https://github.com/owner/repo/pull/123/
+#   https://github.com/owner/repo/pull/123/files
+#   https://github.com/owner/repo/pull/123/commits
 RE_PR_URL = re.compile(
-    r"^https://(?P<github_url>[^/]+)/(?P<owner>[^/]+)/(?P<name>[^/]+)/pull/(?P<number>[0-9]+)/?$"
+    r"^https://(?P<github_url>[^/]+)/(?P<owner>[^/]+)/(?P<name>[^/]+)/pull/(?P<number>[0-9]+)(?:/.*)?$"
+)
+
+# Matches PyTorch HUD URLs like:
+#   https://hud.pytorch.org/pr/169404
+RE_PYTORCH_HUD_URL = re.compile(
+    r"^https://hud\.pytorch\.org/pr/(?P<number>[0-9]+)/?$"
 )
 
 GitHubPullRequestParams = TypedDict(
@@ -144,6 +155,17 @@ def parse_pull_request(
     sh: Optional[ghstack.shell.Shell] = None,
     remote_name: Optional[str] = None,
 ) -> GitHubPullRequestParams:
+    # Check for PyTorch HUD URL first (hud.pytorch.org/pr/NUMBER)
+    hud_match = RE_PYTORCH_HUD_URL.match(pull_request)
+    if hud_match:
+        number = int(hud_match.group("number"))
+        return {
+            "github_url": "github.com",
+            "owner": "pytorch",
+            "name": "pytorch",
+            "number": number,
+        }
+
     m = RE_PR_URL.match(pull_request)
     if not m:
         # We can reconstruct the URL if just a PR number is passed
diff --git a/test_github_utils.py b/test_github_utils.py
new file mode 100644
index 0000000..f7d0917
--- /dev/null
+++ b/test_github_utils.py
@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+
+import unittest
+
+import ghstack.github_utils
+
+
+class TestParsePullRequest(unittest.TestCase):
+    def test_github_url_basic(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/pytorch/pytorch/pull/169404"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_github_url_trailing_slash(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/pytorch/pytorch/pull/169404/"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_github_url_files_suffix(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/pytorch/pytorch/pull/169404/files"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_github_url_commits_suffix(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/pytorch/pytorch/pull/169404/commits"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_github_url_commits_with_sha(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/pytorch/pytorch/pull/169404/commits/abc123def"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_pytorch_hud_url_basic(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://hud.pytorch.org/pr/169404"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_pytorch_hud_url_trailing_slash(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://hud.pytorch.org/pr/169404/"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "pytorch")
+        self.assertEqual(result["name"], "pytorch")
+        self.assertEqual(result["number"], 169404)
+
+    def test_different_owner_repo(self) -> None:
+        result = ghstack.github_utils.parse_pull_request(
+            "https://github.com/facebook/react/pull/12345"
+        )
+        self.assertEqual(result["github_url"], "github.com")
+        self.assertEqual(result["owner"], "facebook")
+        self.assertEqual(result["name"], "react")
+        self.assertEqual(result["number"], 12345)
+
+    def test_invalid_url_raises(self) -> None:
+        with self.assertRaises(RuntimeError):
+            ghstack.github_utils.parse_pull_request("not-a-valid-url")
+
+    def test_invalid_hud_url_raises(self) -> None:
+        with self.assertRaises(RuntimeError):
+            ghstack.github_utils.parse_pull_request("https://hud.pytorch.org/not-pr/123")
+
+
+if __name__ == "__main__":
+    unittest.main()