diff --git a/lib/includes/spdylay/spdylay.h b/lib/includes/spdylay/spdylay.h
index 020fdafc..a6dc683e 100644
--- a/lib/includes/spdylay/spdylay.h
+++ b/lib/includes/spdylay/spdylay.h
@@ -1191,6 +1191,48 @@ int spdylay_session_server_new(spdylay_session **session_ptr,
  */
 void spdylay_session_del(spdylay_session *session);
 
+/**
+ * @enum
+ *
+ * Configuration options for :type:`spdylay_session`.
+ */
+typedef enum {
+  /**
+   * This option prevents the library from sending WINDOW_UPDATE
+   * automatically. If this option is set, the application is
+   * responsible for sending WINDOW_UPDATE using
+   * `spdylay_submit_window_update`.
+   */
+  SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE = 1
+} spdylay_opt;
+
+/**
+ * @function
+ *
+ * Sets the configuration option for the |session|.  The |optname| is
+ * one of :type:`spdylay_opt`. The |optval| is the pointer to the
+ * option value and the |optlen| is the size of |*optval|. The
+ * required type of |optval| varies depending on the |optname|. See
+ * below.
+ *
+ * The following |optname| are supported:
+ *
+ * :enum:`SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE`
+ *     The |optval| must be ``int``. If |optval| is nonzero, the
+ *     library will not send WINDOW_UPDATE automatically.  Therefore,
+ *     the application is responsible for sending WINDOW_UPDATE using
+ *     `spdylay_submit_window_update`. This option defaults to 0.
+ *
+ * This function returns 0 if it succeeds, or one of the following
+ * negative error codes:
+ *
+ * :enum:`SPDYLAY_ERR_INVALID_ARGUMENT`
+ *     The |optname| is not supported; or the |optval| and/or the
+ *     |optlen| are invalid.
+ */
+int spdylay_session_set_option(spdylay_session *session,
+                               int optname, void *optval, size_t optlen);
+
 /**
  * @function
  *
diff --git a/lib/spdylay_session.c b/lib/spdylay_session.c
index 82c380ac..63fa4fcc 100644
--- a/lib/spdylay_session.c
+++ b/lib/spdylay_session.c
@@ -2640,3 +2640,26 @@ const spdylay_origin* spdylay_session_get_client_cert_origin
 {
   return spdylay_client_cert_vector_get_origin(&session->cli_certvec, slot);
 }
+
+
+int spdylay_session_set_option(spdylay_session *session,
+                               int optname, void *optval, size_t optlen)
+{
+  switch(optname) {
+  case SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE:
+    if(optlen == sizeof(int)) {
+      int intval = *(int*)optval;
+      if(intval) {
+        session->opt_flags |= SPDYLAY_OPTMASK_NO_AUTO_WINDOW_UPDATE;
+      } else {
+        session->opt_flags &= ~SPDYLAY_OPTMASK_NO_AUTO_WINDOW_UPDATE;
+      }
+    } else {
+      return SPDYLAY_ERR_INVALID_ARGUMENT;
+    }
+    break;
+  default:
+    return SPDYLAY_ERR_INVALID_ARGUMENT;
+  }
+  return 0;
+}
diff --git a/lib/spdylay_session.h b/lib/spdylay_session.h
index 0f851c98..c5f8f263 100644
--- a/lib/spdylay_session.h
+++ b/lib/spdylay_session.h
@@ -50,6 +50,13 @@
  */
 #define SPDYLAY_PRI_LOWEST_SPDY3 7
 
+/*
+ * Option flags.
+ */
+typedef enum {
+  SPDYLAY_OPTMASK_NO_AUTO_WINDOW_UPDATE = 1 << 0
+} spdylay_optmask;
+
 typedef struct {
   spdylay_outbound_item *item;
   /* Buffer for outbound frames. Used to pack one frame. The memory
@@ -180,6 +187,9 @@ struct spdylay_session {
   /* Settings value of the local endpoint. */
   uint32_t local_settings[SPDYLAY_SETTINGS_MAX+1];
 
+  /* Option flags. This is bitwise-OR of 0 or more of spdylay_optmask. */
+  uint32_t opt_flags;
+
   /* Client certificate vector */
   spdylay_client_cert_vector cli_certvec;
 
diff --git a/tests/main.c b/tests/main.c
index a9514c53..a6893e96 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -152,6 +152,8 @@ int main(int argc, char* argv[])
                    test_spdylay_submit_syn_stream_with_credential) ||
       !CU_add_test(pSuite, "session_set_initial_client_cert_origin",
                    test_spdylay_session_set_initial_client_cert_origin) ||
+      !CU_add_test(pSuite, "session_set_option",
+                   test_spdylay_session_set_option) ||
       !CU_add_test(pSuite, "frame_unpack_nv_spdy2",
                    test_spdylay_frame_unpack_nv_spdy2) ||
       !CU_add_test(pSuite, "frame_unpack_nv_spdy3",
diff --git a/tests/spdylay_session_test.c b/tests/spdylay_session_test.c
index c76e2cac..0fb77ae1 100644
--- a/tests/spdylay_session_test.c
+++ b/tests/spdylay_session_test.c
@@ -2244,3 +2244,39 @@ void test_spdylay_session_set_initial_client_cert_origin(void)
 
   spdylay_session_del(session);
 }
+
+void test_spdylay_session_set_option(void)
+{
+  spdylay_session* session;
+  spdylay_session_callbacks callbacks;
+  int intval;
+  char charval;
+  memset(&callbacks, 0, sizeof(spdylay_session_callbacks));
+  spdylay_session_client_new(&session, SPDYLAY_PROTO_SPDY3, &callbacks, NULL);
+
+  intval = 1;
+  CU_ASSERT(0 ==
+            spdylay_session_set_option(session,
+                                       SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE,
+                                       &intval, sizeof(intval)));
+  CU_ASSERT(session->opt_flags & SPDYLAY_OPTMASK_NO_AUTO_WINDOW_UPDATE);
+
+  intval = 0;
+  CU_ASSERT(0 ==
+            spdylay_session_set_option(session,
+                                       SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE,
+                                       &intval, sizeof(intval)));
+  CU_ASSERT((session->opt_flags & SPDYLAY_OPTMASK_NO_AUTO_WINDOW_UPDATE) == 0);
+
+  CU_ASSERT(SPDYLAY_ERR_INVALID_ARGUMENT ==
+            spdylay_session_set_option(session, 0, /* 0 is invalid optname */
+                                       &intval, sizeof(intval)));
+
+  charval = 1;
+  CU_ASSERT(SPDYLAY_ERR_INVALID_ARGUMENT ==
+            spdylay_session_set_option(session,
+                                       SPDYLAY_OPT_NO_AUTO_WINDOW_UPDATE,
+                                       &charval, sizeof(charval)));
+
+  spdylay_session_del(session);
+}
diff --git a/tests/spdylay_session_test.h b/tests/spdylay_session_test.h
index ea1ff770..e7359706 100644
--- a/tests/spdylay_session_test.h
+++ b/tests/spdylay_session_test.h
@@ -67,5 +67,6 @@ void test_spdylay_session_get_outbound_queue_size(void);
 void test_spdylay_session_prep_credential(void);
 void test_spdylay_submit_syn_stream_with_credential(void);
 void test_spdylay_session_set_initial_client_cert_origin(void);
+void test_spdylay_session_set_option(void);
 
 #endif /* SPDYLAY_SESSION_TEST_H */