Workflow graphs are used to model the control flow of business processes in various languages, e.g., BPMN, EPCs and UML activity diagrams. We present techniques for automatic workflow graph refactoring and completion. These techniques enable various use cases in modeling and runtime optimization. For example they allow us to complete a partial workflow graph, they provide local termination detection for workflow graphs with multiple ends, and they allow us to execute models containing OR-joins faster. Some of our techniques are based on workflow graph parsing and the Refined Process Structure Tree