diff --git a/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp b/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
--- a/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
+++ b/mlir/lib/Conversion/ShapeToStandard/ShapeToStandard.cpp
@@ -56,6 +56,10 @@
     // Add default pass-through conversion.
     addConversion([&](Type type) { return type; });
     addConversion([ctx](shape::SizeType type) { return IndexType::get(ctx); });
+    addConversion([ctx](shape::ShapeType type) {
+      return RankedTensorType::get({ShapedType::kDynamicSize},
+                                   IndexType::get(ctx));
+    });
   }
 };
 
diff --git a/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir b/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
--- a/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
+++ b/mlir/test/Conversion/ShapeToStandard/shape-to-standard.mlir
@@ -29,3 +29,13 @@
   %size = shape.index_to_size %index
   return %size : !shape.size
 }
+
+// -----
+
+// Convert `shape` to `tensor<?xindex>` type.
+// CHECK-LABEL: @shape_id
+// CHECK-SAME: (%[[SHAPE:.*]]: tensor<?xindex>)
+func @shape_id(%shape : !shape.shape) -> !shape.shape {
+  // CHECK: return %[[SHAPE]] : tensor<?xindex>
+  return %shape : !shape.shape
+}