diff --git a/.github/workflows/test-bench.yml b/.github/workflows/test-bench.yml
index 218a70a25c6..ca14d8e42c4 100644
--- a/.github/workflows/test-bench.yml
+++ b/.github/workflows/test-bench.yml
@@ -59,7 +59,29 @@ jobs:
 
       - name: Run benchmarks
         if: '!inputs.cache-warming-only'
-        run: make test-bench
+        # `go test -timeout` doesn't cover benchmarks (the testing alarm stops
+        # before the bench phase), so a hung benchmark would only die at the
+        # 60min job cap — which kills it with no diagnostics. This watchdog
+        # fires first at 45min: SIGQUIT makes the Go runtime dump all goroutine
+        # stacks into this step's log, pinpointing the stall, then fails the job.
+        run: |
+          (
+            sleep 2700
+            {
+              echo "## bench stall watchdog"
+              echo "test-bench exceeded 45min: sent SIGQUIT to the test binaries; goroutine dumps are in the 'Run benchmarks' step log"
+            } >> "$GITHUB_STEP_SUMMARY"
+            pkill -QUIT -f 'go-build.*\.test' || true
+            sleep 120
+            pkill -KILL -f 'go-build.*\.test' || true
+          ) >/dev/null 2>&1 &
+          watchdog_pid=$!
+          cleanup() {
+            pkill -P "$watchdog_pid" 2>/dev/null || true
+            kill "$watchdog_pid" 2>/dev/null || true
+          }
+          trap cleanup EXIT
+          make test-bench
 
       - name: Build test binaries (cache warming)
         if: inputs.cache-warming-only