diff --git a/.clang-format b/.clang-format
new file mode 100644
index 00000000000..7ff88ee0430
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,9 @@
+BasedOnStyle: GNU
+IndentWidth: 4
+
+# override GNU to match Xen ../../CODING_STYLE more closely
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+SpacesInConditionalStatement: true
+SpaceBeforeParens: ControlStatements
+BreakBeforeBraces: Allman
diff --git a/Makefile b/Makefile
index f6e09720185..dcaf1ec598a 100644
--- a/Makefile
+++ b/Makefile
@@ -81,6 +81,7 @@ doc-json:
 
 format:
 	dune build @fmt --auto-promote
+	git ls-files '*.c' '*.h' | xargs clang-format -i
 
 .PHONY: quality-gate
 quality-gate: