diff --git a/boost/asio/ssl/detail/impl/engine.ipp b/boost/asio/ssl/detail/impl/engine.ipp
index f15f2e3..d33935f 100644
--- a/boost/asio/ssl/detail/impl/engine.ipp
+++ b/boost/asio/ssl/detail/impl/engine.ipp
@@ -209,7 +209,7 @@ const boost::system::error_code& engine::map_error_code(
 
   // SSL v2 doesn't provide a protocol-level shutdown, so an eof on the
   // underlying transport is passed through.
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
   if (ssl_->version == SSL2_VERSION)
     return ec;
 #endif // (OPENSSL_VERSION_NUMBER < 0x10100000L)
diff --git a/boost/asio/ssl/detail/impl/openssl_init.ipp b/boost/asio/ssl/detail/impl/openssl_init.ipp
index 94b67f3..acbd926 100644
--- a/boost/asio/ssl/detail/impl/openssl_init.ipp
+++ b/boost/asio/ssl/detail/impl/openssl_init.ipp
@@ -40,7 +40,7 @@ public:
     ::SSL_load_error_strings();        
     ::OpenSSL_add_all_algorithms();
 
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
     mutexes_.resize(::CRYPTO_num_locks());
     for (size_t i = 0; i < mutexes_.size(); ++i)
       mutexes_[i].reset(new boost::asio::detail::mutex);
@@ -68,7 +68,7 @@ public:
 #if (OPENSSL_VERSION_NUMBER < 0x10000000L)
     ::CRYPTO_set_id_callback(0);
 #endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
     ::CRYPTO_set_locking_callback(0);
     ::ERR_free_strings();
     ::EVP_cleanup();
@@ -76,7 +76,7 @@ public:
 #endif // (OPENSSL_VERSION_NUMBER < 0x10100000L)
 #if (OPENSSL_VERSION_NUMBER < 0x10000000L)
     ::ERR_remove_state(0);
-#elif (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#elif (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
     ::ERR_remove_thread_state(NULL);
 #endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
 #if (OPENSSL_VERSION_NUMBER >= 0x10002000L) \
@@ -117,7 +117,7 @@ private:
   }
 #endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
 
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
   static void openssl_locking_func(int mode, int n, 
     const char* /*file*/, int /*line*/)
   {
diff --git a/boost/asio/ssl/error.hpp b/boost/asio/ssl/error.hpp
index 7f85fbd..7e07e65 100644
--- a/boost/asio/ssl/error.hpp
+++ b/boost/asio/ssl/error.hpp
@@ -44,7 +44,7 @@ enum stream_errors
 #if defined(GENERATING_DOCUMENTATION)
   /// The underlying stream closed before the ssl stream gracefully shut down.
   stream_truncated
-#elif (OPENSSL_VERSION_NUMBER < 0x10100000L) && !defined(OPENSSL_IS_BORINGSSL)
+#elif ((OPENSSL_VERSION_NUMBER < 0x10100000L) && !defined(OPENSSL_IS_BORINGSSL)) || defined(LIBRESSL_VERSION_NUMBER)
   stream_truncated = ERR_PACK(ERR_LIB_SSL, 0, SSL_R_SHORT_READ)
 #else
   stream_truncated = 1
diff --git a/boost/asio/ssl/impl/context.ipp b/boost/asio/ssl/impl/context.ipp
index aea2cbd..3ef8c86 100644
--- a/boost/asio/ssl/impl/context.ipp
+++ b/boost/asio/ssl/impl/context.ipp
@@ -130,7 +130,7 @@ context::context(context::method m)
   case context::sslv23_server:
     handle_ = ::SSL_CTX_new(::SSLv23_server_method());
     break;
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || defined(LIBRESSL_VERSION_NUMBER)
 #if defined(SSL_TXT_TLSV1_1)
   case context::tlsv11:
     handle_ = ::SSL_CTX_new(::TLSv1_1_method());
@@ -228,7 +228,7 @@ context::~context()
 {
   if (handle_)
   {
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
     void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
     void* cb_userdata = handle_->default_passwd_callback_userdata;
@@ -239,7 +239,7 @@ context::~context()
         static_cast<detail::password_callback_base*>(
             cb_userdata);
       delete callback;
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
       ::SSL_CTX_set_default_passwd_cb_userdata(handle_, 0);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
       handle_->default_passwd_callback_userdata = 0;
@@ -578,7 +578,7 @@ boost::system::error_code context::use_certificate_chain(
   bio_cleanup bio = { make_buffer_bio(chain) };
   if (bio.p)
   {
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
     pem_password_cb* callback = ::SSL_CTX_get_default_passwd_cb(handle_);
     void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
@@ -682,7 +682,7 @@ boost::system::error_code context::use_private_key(
 {
   ::ERR_clear_error();
 
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
     pem_password_cb* callback = ::SSL_CTX_get_default_passwd_cb(handle_);
     void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
@@ -749,7 +749,7 @@ boost::system::error_code context::use_rsa_private_key(
 {
   ::ERR_clear_error();
 
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
     pem_password_cb* callback = ::SSL_CTX_get_default_passwd_cb(handle_);
     void* cb_userdata = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
@@ -988,7 +988,7 @@ int context::verify_callback_function(int preverified, X509_STORE_CTX* ctx)
 boost::system::error_code context::do_set_password_callback(
     detail::password_callback_base* callback, boost::system::error_code& ec)
 {
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
   void* old_callback = ::SSL_CTX_get_default_passwd_cb_userdata(handle_);
   ::SSL_CTX_set_default_passwd_cb_userdata(handle_, callback);
 #else // (OPENSSL_VERSION_NUMBER >= 0x10100000L)
diff --git a/boost/asio/ssl/impl/error.ipp b/boost/asio/ssl/impl/error.ipp
index e82afba..1629794 100644
--- a/boost/asio/ssl/impl/error.ipp
+++ b/boost/asio/ssl/impl/error.ipp
@@ -53,7 +53,7 @@ const boost::system::error_category& get_ssl_category()
 namespace ssl {
 namespace error {
 
-#if (OPENSSL_VERSION_NUMBER < 0x10100000L) && !defined(OPENSSL_IS_BORINGSSL)
+#if ((OPENSSL_VERSION_NUMBER < 0x10100000L) && !defined(OPENSSL_IS_BORINGSSL)) || defined(LIBRESSL_VERSION_NUMBER)
 
 const boost::system::error_category& get_stream_category()
 {