diff --git a/tools/fast8.sh b/tools/fast8.sh
new file mode 100755
index 0000000000..22976ce09b
--- /dev/null
+++ b/tools/fast8.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+
+NUM_COMMITS=${FAST8_NUM_COMMITS:-1}
+
+if [[ $NUM_COMMITS = "smart" ]]; then
+    # Run on all commits not submitted yet
+    # (sort of -- only checks vs. "master" since this is easy)
+    NUM_COMMITS=$(git cherry master | wc -l)
+fi
+
+echo "Checking last $NUM_COMMITS commits."
+
+cd $(dirname "$0")/..
+CHANGED=$(git diff --name-only HEAD~${NUM_COMMITS} | tr '\n' ' ')
+
+# Skip files that don't exist
+# (have been git rm'd)
+CHECK=""
+for FILE in $CHANGED; do
+    if [ -f "$FILE" ]; then
+        CHECK="$CHECK $FILE"
+    fi
+done
+
+diff -u --from-file /dev/null $CHECK | flake8 --diff
diff --git a/tox.ini b/tox.ini
index 186981cea7..081e956dfa 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,6 +39,13 @@ commands =
   # Run security linter
   bandit -r keystone -x tests
 
+[testenv:fast8]
+basepython = python3
+envdir = {toxworkdir}/pep8
+commands =
+  {toxinidir}/tools/fast8.sh
+passenv = FAST8_NUM_COMMITS
+
 [testenv:bandit]
 basepython = python3
 # NOTE(browne): This is required for the integration test job of the bandit