Index: mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
===================================================================
--- mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
+++ mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td
@@ -138,6 +138,8 @@
   }];
 
   let regions = (region AnyRegion:$region);
+
+  let assemblyFormat = "$region attr-dict";
 }
 
 //===----------------------------------------------------------------------===//
Index: mlir/test/Dialect/OpenMP/ops.mlir
===================================================================
--- mlir/test/Dialect/OpenMP/ops.mlir
+++ mlir/test/Dialect/OpenMP/ops.mlir
@@ -12,6 +12,13 @@
     // CHECK: omp.terminator
     omp.terminator
   }):()->()
+
+  // CHECK: omp.master
+  omp.master {
+    // CHECK: omp.terminator
+    omp.terminator
+  }
+
   return
 }