diff --git a/neuralnetworks/1.0/vts/functional/Callbacks.cpp b/neuralnetworks/1.0/vts/functional/Callbacks.cpp
index a1c5a1a..03afcd0 100644
--- a/neuralnetworks/1.0/vts/functional/Callbacks.cpp
+++ b/neuralnetworks/1.0/vts/functional/Callbacks.cpp
@@ -139,8 +139,10 @@
     return Void();
 }
 
-Return<void> ExecutionCallback::notify_1_2(ErrorStatus errorStatus) {
+Return<void> ExecutionCallback::notify_1_2(ErrorStatus errorStatus,
+                                           const hidl_vec<OutputShape>& outputShapes) {
     mErrorStatus = errorStatus;
+    mOutputShapes = outputShapes;
     CallbackBase::notify();
     return Void();
 }
@@ -150,6 +152,11 @@
     return mErrorStatus;
 }
 
+const std::vector<OutputShape>& ExecutionCallback::getOutputShapes() {
+    wait();
+    return mOutputShapes;
+}
+
 }  // namespace implementation
 }  // namespace V1_2
 }  // namespace neuralnetworks
diff --git a/neuralnetworks/1.0/vts/functional/Callbacks.h b/neuralnetworks/1.0/vts/functional/Callbacks.h
index e89980d..46f29a6 100644
--- a/neuralnetworks/1.0/vts/functional/Callbacks.h
+++ b/neuralnetworks/1.0/vts/functional/Callbacks.h
@@ -275,8 +275,9 @@
      * Either IExecutionCallback::notify or IExecutionCallback::notify_1_2 must
      * be called exactly once on a given ExecutionCallback object.
      *
-     * @param status Error status returned from asynchronously preparing the
-     *               model; will be:
+     * @param status Error status returned from launching the asynchronous task
+     *               (if the launch fails) or from the asynchronous task itself
+     *               (if the launch succeeds). Must be:
      *               - NONE if the asynchronous execution was successful
      *               - DEVICE_UNAVAILABLE if driver is offline or busy
      *               - GENERAL_FAILURE if there is an unspecified error
@@ -285,27 +286,73 @@
      *               - INVALID_ARGUMENT if the input request is invalid
      */
     Return<void> notify(ErrorStatus status) override;
-    Return<void> notify_1_2(ErrorStatus status) override;
+
+    /**
+     * Similar to IExecutionCallback::notify, but for V1_2::IPreparedModel to
+     * also notify output shapes along with error status.
+     *
+     * @param status Error status returned from launching the asynchronous task
+     *               (if the launch fails) or from the asynchronous task itself
+     *               (if the launch succeeds). Must be:
+     *               - NONE if the asynchronous execution was successful
+     *               - DEVICE_UNAVAILABLE if driver is offline or busy
+     *               - GENERAL_FAILURE if the asynchronous task resulted in an
+     *                 unspecified error
+     *               - OUTPUT_INSUFFICIENT_SIZE if at least one output
+     *                 operand buffer is not large enough to store the
+     *                 corresponding output
+     *               - INVALID_ARGUMENT if one of the input arguments to
+     *                 prepareModel is invalid
+     * @param outputShapes A list of shape information of model output operands.
+     *                     The index into "outputShapes" corresponds to the index
+     *                     of the output operand in the Request outputs vector.
+     *                     outputShapes must be empty unless the status is either
+     *                     NONE or OUTPUT_INSUFFICIENT_SIZE.
+     */
+    Return<void> notify_1_2(ErrorStatus status, const hidl_vec<OutputShape>& outputShapes) override;
 
     /**
      * Retrieves the error status returned from the asynchronous task launched
-     * by IPreparedModel::execute. If IPreparedModel::execute has not finished
+     * by either IPreparedModel::execute or IPreparedModel::execute_1_2. If
+     * IPreparedModel::execute or IPreparedModel::execute_1_2 has not finished
      * asynchronously executing, this call will block until the asynchronous task
      * notifies the object.
      *
-     * @return status Error status returned from asynchronously preparing the
-     *                model; will be:
+     * @return status Error status returned from launching the asynchronous task
+     *                (if the launch fails) or from the asynchronous task itself
+     *                (if the launch succeeds). Must be:
      *                - NONE if the asynchronous execution was successful
      *                - DEVICE_UNAVAILABLE if driver is offline or busy
-     *                - GENERAL_FAILURE if there is an unspecified error
-     *                - OUTPUT_INSUFFICIENT_SIZE if provided output buffer is
-     *                  not large enough to store the resultant values
-     *                - INVALID_ARGUMENT if the input request is invalid
+     *                - GENERAL_FAILURE if the asynchronous task resulted in an
+     *                  unspecified error
+     *                - OUTPUT_INSUFFICIENT_SIZE if at least one output
+     *                  operand buffer is not large enough to store the
+     *                  corresponding output
+     *                - INVALID_ARGUMENT if one of the input arguments to
+     *                  prepareModel is invalid
      */
     ErrorStatus getStatus();
 
- private:
+    /**
+     * Retrieves the output shapes returned from the asynchronous task launched
+     * by IPreparedModel::execute_1_2. If IPreparedModel::execute_1_2 has not finished
+     * asynchronously executing, this call will block until the asynchronous task
+     * notifies the object.
+     *
+     * If the asynchronous task was launched by IPreparedModel::execute, an empty vector
+     * will be returned.
+     *
+     * @return outputShapes A list of shape information of model output operands.
+     *                      The index into "outputShapes" corresponds to the index
+     *                      of the output operand in the Request outputs vector.
+     *                      outputShapes must be empty unless the status is either
+     *                      NONE or OUTPUT_INSUFFICIENT_SIZE.
+     */
+    const std::vector<OutputShape>& getOutputShapes();
+
+   private:
     ErrorStatus mErrorStatus;
+    std::vector<OutputShape> mOutputShapes;
 };
 
 
diff --git a/neuralnetworks/1.0/vts/functional/GeneratedTestHarness.cpp b/neuralnetworks/1.0/vts/functional/GeneratedTestHarness.cpp
index 3b4eb21..b5a8607 100644
--- a/neuralnetworks/1.0/vts/functional/GeneratedTestHarness.cpp
+++ b/neuralnetworks/1.0/vts/functional/GeneratedTestHarness.cpp
@@ -89,13 +89,24 @@
                                                 sp<ExecutionCallback>& callback) {
     return preparedModel->execute_1_2(request, callback);
 }
-static Return<ErrorStatus> ExecutePreparedModel(sp<V1_0::IPreparedModel>&, const Request&) {
+static Return<ErrorStatus> ExecutePreparedModel(sp<V1_0::IPreparedModel>&, const Request&,
+                                                hidl_vec<OutputShape>*) {
     ADD_FAILURE() << "asking for synchronous execution at V1_0";
     return ErrorStatus::GENERAL_FAILURE;
 }
 static Return<ErrorStatus> ExecutePreparedModel(sp<V1_2::IPreparedModel>& preparedModel,
-                                                const Request& request) {
-    return preparedModel->executeSynchronously(request);
+                                                const Request& request,
+                                                hidl_vec<OutputShape>* outputShapes) {
+    ErrorStatus result;
+    Return<void> ret = preparedModel->executeSynchronously(
+        request, [&result, &outputShapes](ErrorStatus error, const hidl_vec<OutputShape>& shapes) {
+            result = error;
+            *outputShapes = shapes;
+        });
+    if (!ret.isOk()) {
+        return ErrorStatus::GENERAL_FAILURE;
+    }
+    return result;
 }
 enum class Synchronously { NO, YES };
 const float kDefaultAtol = 1e-5f;
@@ -197,6 +208,8 @@
         inputMemory->commit();
         outputMemory->commit();
 
+        ErrorStatus executionStatus;
+        hidl_vec<OutputShape> outputShapes;
         if (sync == Synchronously::NO) {
             SCOPED_TRACE("asynchronous");
 
@@ -211,18 +224,24 @@
 
             // retrieve execution status
             executionCallback->wait();
-            ErrorStatus executionReturnStatus = executionCallback->getStatus();
-            EXPECT_EQ(ErrorStatus::NONE, executionReturnStatus);
+            executionStatus = executionCallback->getStatus();
+            outputShapes = executionCallback->getOutputShapes();
         } else {
             SCOPED_TRACE("synchronous");
 
             // execute
-            Return<ErrorStatus> executionStatus = ExecutePreparedModel(
-                preparedModel, {.inputs = inputs_info, .outputs = outputs_info, .pools = pools});
-            ASSERT_TRUE(executionStatus.isOk());
-            EXPECT_EQ(ErrorStatus::NONE, static_cast<ErrorStatus>(executionStatus));
+            Return<ErrorStatus> executionReturnStatus = ExecutePreparedModel(
+                preparedModel, {.inputs = inputs_info, .outputs = outputs_info, .pools = pools},
+                &outputShapes);
+            ASSERT_TRUE(executionReturnStatus.isOk());
+            executionStatus = static_cast<ErrorStatus>(executionReturnStatus);
         }
 
+        ASSERT_EQ(ErrorStatus::NONE, executionStatus);
+        // TODO(xusongw): Check if the returned output shapes match with expectation once the
+        //                sample driver implementation of dynamic output shape is finished.
+        ASSERT_EQ(outputShapes.size(), 0);
+
         // validate results
         outputMemory->read();
         copy_back(&test, outputs_info, outputPtr);
diff --git a/neuralnetworks/1.2/Android.bp b/neuralnetworks/1.2/Android.bp
index 7d13104..d8762b0 100644
--- a/neuralnetworks/1.2/Android.bp
+++ b/neuralnetworks/1.2/Android.bp
@@ -27,6 +27,7 @@
         "Operation",
         "OperationType",
         "OperationTypeRange",
+        "OutputShape",
     ],
     gen_java: false,
 }
diff --git a/neuralnetworks/1.2/IExecutionCallback.hal b/neuralnetworks/1.2/IExecutionCallback.hal
index 667e0d6..47de1b6 100644
--- a/neuralnetworks/1.2/IExecutionCallback.hal
+++ b/neuralnetworks/1.2/IExecutionCallback.hal
@@ -18,6 +18,7 @@
 
 import @1.0::ErrorStatus;
 import @1.0::IExecutionCallback;
+import OutputShape;
 
 /**
  * IExecutionCallback must be used to return the error status result from an
@@ -39,10 +40,16 @@
      *               - DEVICE_UNAVAILABLE if driver is offline or busy
      *               - GENERAL_FAILURE if the asynchronous task resulted in an
      *                 unspecified error
-     *               - OUTPUT_INSUFFICIENT_SIZE if provided output buffer is
-     *                 not large enough to store the resultant values
+     *               - OUTPUT_INSUFFICIENT_SIZE if at least one output
+     *                 operand buffer is not large enough to store the
+     *                 corresponding output
      *               - INVALID_ARGUMENT if one of the input arguments to
      *                 prepareModel is invalid
+     * @param outputShapes A list of shape information of model output operands.
+     *                     The index into "outputShapes" corresponds with to index
+     *                     of the output operand in the Request outputs vector.
+     *                     outputShapes must be empty unless the status is either
+     *                     NONE or OUTPUT_INSUFFICIENT_SIZE.
      */
-    oneway notify_1_2(ErrorStatus status);
+    oneway notify_1_2(ErrorStatus status, vec<OutputShape> outputShapes);
 };
diff --git a/neuralnetworks/1.2/IPreparedModel.hal b/neuralnetworks/1.2/IPreparedModel.hal
index 4e91c67..044ca28 100644
--- a/neuralnetworks/1.2/IPreparedModel.hal
+++ b/neuralnetworks/1.2/IPreparedModel.hal
@@ -100,11 +100,17 @@
      *                - NONE if execution is performed successfully
      *                - DEVICE_UNAVAILABLE if driver is offline or busy
      *                - GENERAL_FAILURE if there is an unspecified error
-     *                - OUTPUT_INSUFFICIENT_SIZE if provided output buffer is
-     *                  not large enough to store the resultant values
+     *                - OUTPUT_INSUFFICIENT_SIZE if at least one output
+     *                  operand buffer is not large enough to store the
+     *                  corresponding output
      *                - INVALID_ARGUMENT if one of the input arguments is
      *                  invalid
+     * @return outputShapes A list of shape information of model output operands.
+     *                      The index into "outputShapes" corresponds to the index
+     *                      of the output operand in the Request outputs vector.
+     *                      outputShapes must be empty unless the status is either
+     *                      NONE or OUTPUT_INSUFFICIENT_SIZE.
      */
     executeSynchronously(Request request)
-        generates (ErrorStatus status);
+        generates (ErrorStatus status, vec<OutputShape> outputShapes);
 };
diff --git a/neuralnetworks/1.2/types.hal b/neuralnetworks/1.2/types.hal
index 40c07e7..4738cc3 100644
--- a/neuralnetworks/1.2/types.hal
+++ b/neuralnetworks/1.2/types.hal
@@ -234,9 +234,6 @@
      *
      * For a scalar operand, dimensions.size() must be 0.
      *
-     * For a tensor operand, dimensions.size() must be at least 1;
-     * however, any of the dimensions may be unspecified.
-     *
      * A tensor operand with all dimensions specified has "fully
      * specified" dimensions. Whenever possible (i.e., whenever the
      * dimensions are known at model construction time), a tensor
@@ -255,17 +252,20 @@
      *     . The operand has lifetime CONSTANT_COPY or
      *       CONSTANT_REFERENCE.
      *
-     *     . The operand has lifetime MODEL_INPUT or MODEL_OUTPUT. Fully
+     *     . The operand has lifetime MODEL_INPUT. Fully
      *       specified dimensions must either be present in the
      *       Operand or they must be provided in the corresponding
      *       RequestArgument.
-     *       EXCEPTION: If the input or output is optional and omitted
+     *       EXCEPTION: If the input is optional and omitted
      *       (by setting the hasNoValue field of the corresponding
      *       RequestArgument to true) then it need not have fully
      *       specified dimensions.
      *
      * A tensor operand with some number of unspecified dimensions is
      * represented by setting each unspecified dimension to 0.
+     *
+     * A tensor operand with unspecified rank is represented by providing
+     * an empty dimensions vector.
      */
     vec<uint32_t> dimensions;
 
@@ -397,3 +397,18 @@
      */
     bool relaxComputationFloat32toFloat16;
 };
+
+/**
+ * Describes the shape information of an output operand after execution.
+ */
+struct OutputShape {
+    /**
+     * Dimensions of the operand.
+     */
+    vec<uint32_t> dimensions;
+
+    /**
+     * Whether the provided buffer size is sufficient for the output.
+     */
+    bool isSufficient;
+};
diff --git a/neuralnetworks/1.2/vts/functional/ValidateRequest.cpp b/neuralnetworks/1.2/vts/functional/ValidateRequest.cpp
index d80fbcf..1eaea4b 100644
--- a/neuralnetworks/1.2/vts/functional/ValidateRequest.cpp
+++ b/neuralnetworks/1.2/vts/functional/ValidateRequest.cpp
@@ -110,15 +110,20 @@
 
         executionCallback->wait();
         ErrorStatus executionReturnStatus = executionCallback->getStatus();
+        const auto& outputShapes = executionCallback->getOutputShapes();
         ASSERT_EQ(ErrorStatus::INVALID_ARGUMENT, executionReturnStatus);
+        ASSERT_EQ(outputShapes.size(), 0);
     }
 
     {
         SCOPED_TRACE(message + " [executeSynchronously]");
 
-        Return<ErrorStatus> executeStatus = preparedModel->executeSynchronously(request);
+        Return<void> executeStatus = preparedModel->executeSynchronously(
+            request, [](ErrorStatus error, const hidl_vec<OutputShape>& outputShapes) {
+                ASSERT_EQ(ErrorStatus::INVALID_ARGUMENT, error);
+                EXPECT_EQ(outputShapes.size(), 0);
+            });
         ASSERT_TRUE(executeStatus.isOk());
-        ASSERT_EQ(ErrorStatus::INVALID_ARGUMENT, static_cast<ErrorStatus>(executeStatus));
     }
 }