diff --git a/bedevere/__main__.py b/bedevere/__main__.py
index 3a3c0740..c407b194 100644
--- a/bedevere/__main__.py
+++ b/bedevere/__main__.py
@@ -11,13 +11,13 @@
 from gidgethub import routing
 from gidgethub import sansio
 
-from . import backport, gh_issue, close_pr, filepaths, news, stage
+from . import backport, conflict, gh_issue, close_pr, filepaths, news, stage
 
 import sentry_sdk
 
 router = routing.Router(backport.router, gh_issue.router, close_pr.router,
                         filepaths.router, news.router,
-                        stage.router)
+                        stage.router, conflict.router)
 cache = cachetools.LRUCache(maxsize=500)
 
 sentry_sdk.init(os.environ.get("SENTRY_DSN"))
diff --git a/bedevere/conflict.py b/bedevere/conflict.py
new file mode 100644
index 00000000..58b106bd
--- /dev/null
+++ b/bedevere/conflict.py
@@ -0,0 +1,84 @@
+import asyncio
+
+import gidgethub.routing
+from gidgethub.abc import GitHubAPI
+
+router = gidgethub.routing.Router()
+
+MERGE_CONFLICT_LABEL = "merge-conflict"
+
+
+@router.register("push")
+async def new_commit_pushed_to_main(event, gh: GitHubAPI, *arg, **kwargs) -> None:
+    """If there is a new commit pushed to main, update all open PRs merge status."""
+    if event.data["ref"] != "refs/heads/main":
+        return
+
+    prs_to_add_conflict_label = []
+    prs_to_remove_conflict_label = []
+
+    after = None
+    while True:
+        query = """
+query ($after: String) {
+  repository(name: "cpython", owner: "python") {
+    id
+    pullRequests(first: 10, after: $after, states: OPEN) {
+      nodes {
+        id
+        mergeable
+        number
+        # title
+        # url
+        # state
+        labels(first: 100) {
+          edges {
+            node {
+              name
+            }
+          }
+        }
+      }
+      pageInfo {
+        endCursor
+        hasNextPage
+      }
+    }
+  }
+  rateLimit {
+    remaining
+  }
+}
+"""
+        data = await gh.graphql(query, after=after)
+        for pr in data["repository"]["pullRequests"]["nodes"]:
+            has_conflict_label = MERGE_CONFLICT_LABEL in (
+                edge["node"]["name"] for edge in pr["labels"]["edges"]
+            )
+            if pr["mergeable"] == "CONFLICTING":
+                if not has_conflict_label:
+                    prs_to_add_conflict_label.append(pr)
+            else:
+                if has_conflict_label:
+                    prs_to_remove_conflict_label.append(pr)
+
+        if data["rateLimit"]["remaining"] < 1000:
+            break
+        after = data["repository"]["pullRequests"]["pageInfo"]["endCursor"]
+        if not data["repository"]["pullRequests"]["pageInfo"]["hasNextPage"]:
+            break
+
+    futs = [
+        gh.post(
+            f"https://api.github.com/repos/python/cpython/issues/{pr['number']}/labels",
+            data={"labels": [MERGE_CONFLICT_LABEL]},
+        )
+        for pr in prs_to_add_conflict_label
+    ] + [
+        gh.delete(
+            f"https://api.github.com/repos/python/cpython/issues/{pr['number']}/labels/{MERGE_CONFLICT_LABEL}",
+        )
+        for pr in prs_to_remove_conflict_label
+    ]
+    for fut in asyncio.as_completed(futs):
+        await fut