diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 7e086c1..18967fb 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1650,7 +1650,6 @@
 #define SSL_CTRL_GET_CURVES 90
 #define SSL_CTRL_SET_CURVES 91
 #define SSL_CTRL_SET_CURVES_LIST 92
-#define SSL_CTRL_SET_ECDH_AUTO 94
 #define SSL_CTRL_SET_SIGALGS 97
 #define SSL_CTRL_SET_SIGALGS_LIST 98
 #define SSL_CTRL_CERT_FLAGS 99
@@ -1711,6 +1710,12 @@
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_TMP_RSA, 0, (char *)rsa)
 #define SSL_CTX_set_tmp_dh(ctx, dh) \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_TMP_DH, 0, (char *)dh)
+
+/* SSL_CTX_set_tmp_ecdh configures |ctx| to use the curve from |ecdh| (a const
+ * EC_KEY *) as the curve for ephemeral ECDH keys. For historical reasons, this
+ * API expects an |EC_KEY|, but only the curve is used. It returns one on
+ * success and zero on error. If unset, an appropriate curve will be chosen
+ * automatically. (This is recommended.) */
 #define SSL_CTX_set_tmp_ecdh(ctx, ecdh) \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_TMP_ECDH, 0, (char *)ecdh)
 
@@ -1719,6 +1724,12 @@
   SSL_ctrl(ssl, SSL_CTRL_SET_TMP_RSA, 0, (char *)rsa)
 #define SSL_set_tmp_dh(ssl, dh) \
   SSL_ctrl(ssl, SSL_CTRL_SET_TMP_DH, 0, (char *)dh)
+
+/* SSL_set_tmp_ecdh configures |ssl| to use the curve from |ecdh| (a const
+ * EC_KEY *) as the curve for ephemeral ECDH keys. For historical reasons, this
+ * API expects an |EC_KEY|, but only the curve is used. It returns one on
+ * success and zero on error. If unset, an appropriate curve will be chosen
+ * automatically. (This is recommended.) */
 #define SSL_set_tmp_ecdh(ssl, ecdh) \
   SSL_ctrl(ssl, SSL_CTRL_SET_TMP_ECDH, 0, (char *)ecdh)
 
@@ -1809,10 +1820,6 @@
   SSL_ctrl(ctx, SSL_CTRL_SET_CURVES, clistlen, (char *)clist)
 #define SSL_set1_curves_list(ctx, s) \
   SSL_ctrl(ctx, SSL_CTRL_SET_CURVES_LIST, 0, (char *)s)
-#define SSL_CTX_set_ecdh_auto(ctx, onoff) \
-  SSL_CTX_ctrl(ctx, SSL_CTRL_SET_ECDH_AUTO, onoff, NULL)
-#define SSL_set_ecdh_auto(s, onoff) \
-  SSL_ctrl(s, SSL_CTRL_SET_ECDH_AUTO, onoff, NULL)
 
 #define SSL_CTX_set1_sigalgs(ctx, slist, slistlen) \
   SSL_CTX_ctrl(ctx, SSL_CTRL_SET_SIGALGS, slistlen, (int *)slist)
@@ -2201,10 +2208,34 @@
 OPENSSL_EXPORT void SSL_set_tmp_dh_callback(SSL *ssl,
                                             DH *(*dh)(SSL *ssl, int is_export,
                                                       int keylength));
+
+/* SSL_CTX_set_tmp_ecdh_callback configures |ctx| to use |callback| to determine
+ * the curve for ephemeral ECDH keys. |callback| should ignore |is_export| and
+ * |keylength| and return an |EC_KEY| of the selected curve or NULL on
+ * error. Only the curve is used, so the |EC_KEY| needn't have a generated
+ * keypair.
+ *
+ * If the callback is unset, an appropriate curve will be chosen automatically.
+ * (This is recommended.)
+ *
+ * WARNING: The caller does not take ownership of the resulting |EC_KEY|, so
+ * |callback| must save and release the object elsewhere. */
 OPENSSL_EXPORT void SSL_CTX_set_tmp_ecdh_callback(
-    SSL_CTX *ctx, EC_KEY *(*ecdh)(SSL *ssl, int is_export, int keylength));
+    SSL_CTX *ctx, EC_KEY *(*callback)(SSL *ssl, int is_export, int keylength));
+
+/* SSL_set_tmp_ecdh_callback configures |ssl| to use |callback| to determine the
+ * curve for ephemeral ECDH keys. |callback| should ignore |is_export| and
+ * |keylength| and return an |EC_KEY| of the selected curve or NULL on
+ * error. Only the curve is used, so the |EC_KEY| needn't have a generated
+ * keypair.
+ *
+ * If the callback is unset, an appropriate curve will be chosen automatically.
+ * (This is recommended.)
+ *
+ * WARNING: The caller does not take ownership of the resulting |EC_KEY|, so
+ * |callback| must save and release the object elsewhere. */
 OPENSSL_EXPORT void SSL_set_tmp_ecdh_callback(
-    SSL *ssl, EC_KEY *(*ecdh)(SSL *ssl, int is_export, int keylength));
+    SSL *ssl, EC_KEY *(*callback)(SSL *ssl, int is_export, int keylength));
 
 OPENSSL_EXPORT const void *SSL_get_current_compression(SSL *s);
 OPENSSL_EXPORT const void *SSL_get_current_expansion(SSL *s);
@@ -2291,6 +2322,12 @@
 OPENSSL_EXPORT const SSL_METHOD *DTLSv1_2_server_method(void);
 OPENSSL_EXPORT const SSL_METHOD *DTLSv1_2_client_method(void);
 
+/* SSL_CTX_set_ecdh_auto returns one. */
+#define SSL_CTX_set_ecdh_auto(ctx, onoff) 1
+
+/* SSL_set_ecdh_auto returns one. */
+#define SSL_set_ecdh_auto(ssl, onoff) 1
+
 
 /* Android compatibility section.
  *
diff --git a/ssl/internal.h b/ssl/internal.h
index 32f7f51..c981394 100644
--- a/ssl/internal.h
+++ b/ssl/internal.h
@@ -454,13 +454,15 @@
 
   DH *dh_tmp;
   DH *(*dh_tmp_cb)(SSL *ssl, int is_export, int keysize);
+
   /* ecdh_nid, if not |NID_undef|, is the NID of the curve to use for ephemeral
-   * ECDH keys. */
+   * ECDH keys. If unset, |ecdh_tmp_cb| is consulted. */
   int ecdh_nid;
-  /* Callback for generating ephemeral ECDH keys */
+  /* ecdh_tmp_cb is a callback for selecting the curve to use for ephemeral ECDH
+   * keys. If NULL, a curve is selected automatically. See
+   * |SSL_CTX_set_tmp_ecdh_callback|. */
   EC_KEY *(*ecdh_tmp_cb)(SSL *ssl, int is_export, int keysize);
-  /* Select ECDH parameters automatically */
-  int ecdh_tmp_auto;
+
   /* Flags related to certificates */
   unsigned int cert_flags;
   CERT_PKEY pkeys[SSL_PKEY_NUM];
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index 9c295e9..3d80565 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -676,7 +676,7 @@
     case SSL_CTRL_SET_TMP_ECDH: {
       /* For historical reasons, this API expects an |EC_KEY|, but only the
        * group is used. */
-      EC_KEY *ec_key = (EC_KEY *)parg;
+      const EC_KEY *ec_key = (const EC_KEY *)parg;
       if (ec_key == NULL || EC_KEY_get0_group(ec_key) == NULL) {
         OPENSSL_PUT_ERROR(SSL, ssl3_ctrl, ERR_R_PASSED_NULL_PARAMETER);
         return ret;
@@ -766,10 +766,6 @@
       return tls1_set_curves(&s->tlsext_ellipticcurvelist,
                              &s->tlsext_ellipticcurvelist_length, parg, larg);
 
-    case SSL_CTRL_SET_ECDH_AUTO:
-      s->cert->ecdh_tmp_auto = larg;
-      return 1;
-
     case SSL_CTRL_SET_SIGALGS:
       return tls1_set_sigalgs(s->cert, parg, larg, 0);
 
@@ -945,7 +941,7 @@
     case SSL_CTRL_SET_TMP_ECDH: {
       /* For historical reasons, this API expects an |EC_KEY|, but only the
        * group is used. */
-      EC_KEY *ec_key = (EC_KEY *)parg;
+      const EC_KEY *ec_key = (const EC_KEY *)parg;
       if (ec_key == NULL || EC_KEY_get0_group(ec_key) == NULL) {
         OPENSSL_PUT_ERROR(SSL, ssl3_ctx_ctrl, ERR_R_PASSED_NULL_PARAMETER);
         return 0;
@@ -993,10 +989,6 @@
       return tls1_set_curves(&ctx->tlsext_ellipticcurvelist,
                              &ctx->tlsext_ellipticcurvelist_length, parg, larg);
 
-    case SSL_CTRL_SET_ECDH_AUTO:
-      ctx->cert->ecdh_tmp_auto = larg;
-      return 1;
-
     case SSL_CTRL_SET_SIGALGS:
       return tls1_set_sigalgs(ctx->cert, parg, larg, 0);
 
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index a25775f..8f5712e 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -1410,9 +1410,7 @@
     } else if (alg_k & SSL_kECDHE) {
       /* Determine the curve to use. */
       int nid = NID_undef;
-      if (cert->ecdh_tmp_auto) {
-        nid = tls1_get_shared_curve(s);
-      } else if (cert->ecdh_nid != NID_undef) {
+      if (cert->ecdh_nid != NID_undef) {
         nid = cert->ecdh_nid;
       } else if (cert->ecdh_tmp_cb != NULL) {
         /* Note: |ecdh_tmp_cb| does NOT pass ownership of the result
@@ -1421,6 +1419,8 @@
         if (template != NULL && EC_KEY_get0_group(template) != NULL) {
           nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(template));
         }
+      } else {
+        nid = tls1_get_shared_curve(s);
       }
       if (nid == NID_undef) {
         al = SSL_AD_HANDSHAKE_FAILURE;
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index 14c5e31..313562b 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -216,7 +216,6 @@
 
   ret->ecdh_nid = cert->ecdh_nid;
   ret->ecdh_tmp_cb = cert->ecdh_tmp_cb;
-  ret->ecdh_tmp_auto = cert->ecdh_tmp_auto;
 
   for (i = 0; i < SSL_PKEY_NUM; i++) {
     CERT_PKEY *cpk = cert->pkeys + i;
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index c491b12..2244dbd 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2004,7 +2004,6 @@
   int rsa_enc, rsa_sign, dh_tmp;
   uint32_t mask_k, mask_a;
   int have_ecc_cert, ecdsa_ok;
-  int have_ecdh_tmp;
   X509 *x;
 
   if (c == NULL) {
@@ -2016,8 +2015,6 @@
 
   dh_tmp = (c->dh_tmp != NULL || c->dh_tmp_cb != NULL);
 
-  have_ecdh_tmp = (c->ecdh_nid != NID_undef || c->ecdh_tmp_cb != NULL ||
-                   c->ecdh_tmp_auto);
   rsa_enc = ssl_has_key(s, SSL_PKEY_RSA_ENC);
   rsa_sign = ssl_has_key(s, SSL_PKEY_RSA_SIGN);
   have_ecc_cert = ssl_has_key(s, SSL_PKEY_ECC);
@@ -2053,7 +2050,7 @@
 
   /* If we are considering an ECC cipher suite that uses an ephemeral EC
    * key, check it. */
-  if (have_ecdh_tmp && tls1_check_ec_tmp_key(s)) {
+  if (tls1_check_ec_tmp_key(s)) {
     mask_k |= SSL_kECDHE;
   }
 
@@ -2625,15 +2622,16 @@
 }
 
 void SSL_CTX_set_tmp_ecdh_callback(SSL_CTX *ctx,
-                                   EC_KEY *(*ecdh)(SSL *ssl, int is_export,
-                                                   int keylength)) {
-  SSL_CTX_callback_ctrl(ctx, SSL_CTRL_SET_TMP_ECDH_CB, (void (*)(void))ecdh);
+                                   EC_KEY *(*callback)(SSL *ssl, int is_export,
+                                                       int keylength)) {
+  SSL_CTX_callback_ctrl(ctx, SSL_CTRL_SET_TMP_ECDH_CB,
+                        (void (*)(void))callback);
 }
 
 void SSL_set_tmp_ecdh_callback(SSL *ssl,
-                               EC_KEY *(*ecdh)(SSL *ssl, int is_export,
-                                               int keylength)) {
-  SSL_callback_ctrl(ssl, SSL_CTRL_SET_TMP_ECDH_CB, (void (*)(void))ecdh);
+                               EC_KEY *(*callback)(SSL *ssl, int is_export,
+                                                   int keylength)) {
+  SSL_callback_ctrl(ssl, SSL_CTRL_SET_TMP_ECDH_CB, (void (*)(void))callback);
 }
 
 int SSL_CTX_use_psk_identity_hint(SSL_CTX *ctx, const char *identity_hint) {
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index fdbb340..1e495b3 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -633,22 +633,22 @@
 }
 
 int tls1_check_ec_tmp_key(SSL *s) {
-  if (s->cert->ecdh_tmp_auto) {
-    /* If using |ecdh_tmp_auto|, ECDH is acceptable if there is a shared
-     * curve. */
-    return tls1_get_shared_curve(s) != NID_undef;
-  }
-
   if (s->cert->ecdh_nid != NID_undef) {
-    /* If the curve is preconfigured, ECDH is acceptable if the peer supports
+    /* If the curve is preconfigured, ECDH is acceptable iff the peer supports
      * the curve. */
     uint16_t curve_id;
     return tls1_ec_nid2curve_id(&curve_id, s->cert->ecdh_nid) &&
            tls1_check_curve_id(s, curve_id);
   }
 
-  /* Otherwise, assume the callback will provide an acceptable curve. */
-  return s->cert->ecdh_tmp_cb != NULL;
+  if (s->cert->ecdh_tmp_cb != NULL) {
+    /* Assume the callback will provide an acceptable curve. */
+    return 1;
+  }
+
+  /* Otherwise, the curve gets selected automatically. ECDH is acceptable iff
+   * there is a shared curve. */
+  return tls1_get_shared_curve(s) != NID_undef;
 }
 
 /* List of supported signature algorithms and hashes. Should make this
diff --git a/ssl/test/bssl_shim.cc b/ssl/test/bssl_shim.cc
index fd4bd60..bf526b8 100644
--- a/ssl/test/bssl_shim.cc
+++ b/ssl/test/bssl_shim.cc
@@ -413,10 +413,6 @@
     SSL_CTX_set_read_ahead(ssl_ctx.get(), 1);
   }
 
-  if (!SSL_CTX_set_ecdh_auto(ssl_ctx.get(), 1)) {
-    return nullptr;
-  }
-
   if (!SSL_CTX_set_cipher_list(ssl_ctx.get(), "ALL")) {
     return nullptr;
   }