diff --git a/cmake/FindLLHTTP.cmake b/cmake/FindLLHTTP.cmake
new file mode 100644
index 000000000..a87d335d0
--- /dev/null
+++ b/cmake/FindLLHTTP.cmake
@@ -0,0 +1,39 @@
+# - Try to find llhttp
+#
+# Defines the following variables:
+#
+# LLHTTP_FOUND - system has llhttp
+# LLHTTP_INCLUDE_DIR - the llhttp include directory
+# LLHTTP_LIBRARIES - Link these to use llhttp
+# LLHTTP_VERSION_MAJOR - major version
+# LLHTTP_VERSION_MINOR - minor version
+# LLHTTP_VERSION_STRING - the version of llhttp found
+
+# Find the header and library
+find_path(LLHTTP_INCLUDE_DIR NAMES llhttp.h)
+find_library(LLHTTP_LIBRARY NAMES llhttp libllhttp)
+
+# Found the header, read version
+if(LLHTTP_INCLUDE_DIR AND EXISTS "${LLHTTP_INCLUDE_DIR}/llhttp.h")
+	file(READ "${LLHTTP_INCLUDE_DIR}/llhttp.h" LLHTTP_H)
+	if(LLHTTP_H)
+		string(REGEX REPLACE ".*#define[\t ]+LLHTTP_VERSION_MAJOR[\t ]+([0-9]+).*" "\\1" LLHTTP_VERSION_MAJOR "${LLHTTP_H}")
+		string(REGEX REPLACE ".*#define[\t ]+LLHTTP_VERSION_MINOR[\t ]+([0-9]+).*" "\\1" LLHTTP_VERSION_MINOR "${LLHTTP_H}")
+		set(LLHTTP_VERSION_STRING "${LLHTTP_VERSION_MAJOR}.${LLHTTP_VERSION_MINOR}")
+	endif()
+	unset(LLHTTP_H)
+endif()
+
+# Handle the QUIETLY and REQUIRED arguments and set LLHTTP_FOUND
+# to TRUE if all listed variables are TRUE
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LLHTTP REQUIRED_VARS LLHTTP_INCLUDE_DIR LLHTTP_LIBRARY)
+
+# Hide advanced variables
+mark_as_advanced(LLHTTP_INCLUDE_DIR LLHTTP_LIBRARY)
+
+# Set standard variables
+if(LLHTTP_FOUND)
+	set(LLHTTP_LIBRARIES ${LLHTTP_LIBRARY})
+	set(LLHTTP_INCLUDE_DIRS ${LLHTTP_INCLUDE_DIR})
+endif()
diff --git a/cmake/SelectHTTPParser.cmake b/cmake/SelectHTTPParser.cmake
index 955aea330..aa6711d96 100644
--- a/cmake/SelectHTTPParser.cmake
+++ b/cmake/SelectHTTPParser.cmake
@@ -1,19 +1,39 @@
 # Optional external dependency: http-parser
-if(USE_HTTP_PARSER STREQUAL "system")
-	find_package(HTTPParser)
+if(USE_HTTP_PARSER STREQUAL "builtin")
+    message(STATUS "support for bundled (legacy) http-parser explicitly requested")
 
-	if(HTTP_PARSER_FOUND AND HTTP_PARSER_VERSION_MAJOR EQUAL 2)
-		list(APPEND LIBGIT2_SYSTEM_INCLUDES ${HTTP_PARSER_INCLUDE_DIRS})
-		list(APPEND LIBGIT2_SYSTEM_LIBS ${HTTP_PARSER_LIBRARIES})
-		list(APPEND LIBGIT2_PC_LIBS "-lhttp_parser")
-		add_feature_info(http-parser ON "http-parser support (system)")
-	else()
-		message(FATAL_ERROR "http-parser support was requested but not found")
-	endif()
-else()
-	message(STATUS "http-parser version 2 was not found or disabled; using bundled 3rd-party sources.")
 	add_subdirectory("${PROJECT_SOURCE_DIR}/deps/http-parser" "${PROJECT_BINARY_DIR}/deps/http-parser")
 	list(APPEND LIBGIT2_DEPENDENCY_INCLUDES "${PROJECT_SOURCE_DIR}/deps/http-parser")
 	list(APPEND LIBGIT2_DEPENDENCY_OBJECTS "$<TARGET_OBJECTS:http-parser>")
 	add_feature_info(http-parser ON "http-parser support (bundled)")
+else()
+    # By default, try to use system LLHTTP. Fall back to
+    # system http-parser, and even to bundled http-parser
+    # as a last resort.
+    find_package(LLHTTP)
+
+	if(LLHTTP_FOUND AND LLHTTP_VERSION_MAJOR EQUAL 9)
+	    add_compile_definitions(USE_LLHTTP)
+		list(APPEND LIBGIT2_SYSTEM_INCLUDES ${LLHTTP_INCLUDE_DIRS})
+		list(APPEND LIBGIT2_SYSTEM_LIBS ${LLHTTP_LIBRARIES})
+		list(APPEND LIBGIT2_PC_LIBS "-lllhttp")
+		add_feature_info(llhttp ON "llhttp support (system)")
+	else()
+        message(STATUS "llhttp support was requested but not found; checking (legacy) http-parser support")
+        find_package(HTTPParser)
+
+        if(HTTP_PARSER_FOUND AND HTTP_PARSER_VERSION_MAJOR EQUAL 2)
+            list(APPEND LIBGIT2_SYSTEM_INCLUDES ${HTTP_PARSER_INCLUDE_DIRS})
+            list(APPEND LIBGIT2_SYSTEM_LIBS ${HTTP_PARSER_LIBRARIES})
+            list(APPEND LIBGIT2_PC_LIBS "-lhttp_parser")
+            add_feature_info(http-parser ON "http-parser support (system)")
+        else()
+            message(STATUS "neither llhttp nor http-parser support was found; proceeding with bundled (legacy) http-parser")
+
+            add_subdirectory("${PROJECT_SOURCE_DIR}/deps/http-parser" "${PROJECT_BINARY_DIR}/deps/http-parser")
+            list(APPEND LIBGIT2_DEPENDENCY_INCLUDES "${PROJECT_SOURCE_DIR}/deps/http-parser")
+            list(APPEND LIBGIT2_DEPENDENCY_OBJECTS "$<TARGET_OBJECTS:http-parser>")
+            add_feature_info(http-parser ON "http-parser support (bundled)")
+        endif()
+    endif()
 endif()
diff --git a/src/libgit2/transports/http.c b/src/libgit2/transports/http.c
index 8437674fc..fc2161b60 100644
--- a/src/libgit2/transports/http.c
+++ b/src/libgit2/transports/http.c
@@ -9,7 +9,6 @@
 
 #ifndef GIT_WINHTTP
 
-#include "http_parser.h"
 #include "net.h"
 #include "remote.h"
 #include "smart.h"
diff --git a/src/libgit2/transports/httpclient.c b/src/libgit2/transports/httpclient.c
index e22a07ba1..6e3491ed2 100644
--- a/src/libgit2/transports/httpclient.c
+++ b/src/libgit2/transports/httpclient.c
@@ -7,7 +7,32 @@
 
 #include "common.h"
 #include "git2.h"
-#include "http_parser.h"
+
+#ifdef USE_LLHTTP
+#include <llhttp.h>
+typedef llhttp_settings_t http_settings_t;
+typedef llhttp_t http_parser_t;
+GIT_INLINE(http_settings_t *) http_client_parser_settings(void);
+#define git_http_parser_init(parser) llhttp_init(parser, HTTP_RESPONSE, http_client_parser_settings())
+#define git_http_parser_pause(parser) llhttp_pause(parser)
+#define git_http_parser_resume(parser) llhttp_resume(parser)
+#define git_http_parser_errno(parser) parser.error
+#define git_http_should_keep_alive(parser) llhttp_should_keep_alive(parser)
+#define git_http_errno_description(parser, errno) llhttp_get_error_reason(parser)
+#else
+#include <http_parser.h>
+/* Legacy http-parser. */
+typedef http_parser_settings http_settings_t;
+typedef struct http_parser http_parser_t;
+GIT_INLINE(http_settings_t *) http_client_parser_settings(void);
+#define git_http_parser_init(parser) http_parser_init(parser, HTTP_RESPONSE)
+#define git_http_parser_pause(parser) http_parser_pause(parser, 1)
+#define git_http_parser_resume(parser) http_parser_pause(parser, 0)
+#define git_http_parser_errno(parser) parser.http_errno
+#define git_http_should_keep_alive(parser) http_should_keep_alive(parser)
+#define git_http_errno_description(parser, errno) http_errno_description(errno)
+#endif /* USE_LLHTTP */
+
 #include "vector.h"
 #include "trace.h"
 #include "httpclient.h"
@@ -108,7 +133,7 @@ struct git_http_client {
 	git_http_server_t current_server;
 	http_client_state state;
 
-	http_parser parser;
+	http_parser_t parser;
 
 	git_http_server server;
 	git_http_server proxy;
@@ -154,7 +179,7 @@ void git_http_response_dispose(git_http_response *response)
 	memset(response, 0, sizeof(git_http_response));
 }
 
-static int on_header_complete(http_parser *parser)
+static int on_header_complete(http_parser_t *parser)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 	git_http_client *client = ctx->client;
@@ -219,7 +244,7 @@ static int on_header_complete(http_parser *parser)
 	return 0;
 }
 
-static int on_header_field(http_parser *parser, const char *str, size_t len)
+static int on_header_field(http_parser_t *parser, const char *str, size_t len)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 
@@ -254,7 +279,7 @@ static int on_header_field(http_parser *parser, const char *str, size_t len)
 	return 0;
 }
 
-static int on_header_value(http_parser *parser, const char *str, size_t len)
+static int on_header_value(http_parser_t *parser, const char *str, size_t len)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 
@@ -342,7 +367,7 @@ static int resend_needed(git_http_client *client, git_http_response *response)
 	return 0;
 }
 
-static int on_headers_complete(http_parser *parser)
+static int on_headers_complete(http_parser_t *parser)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 
@@ -365,7 +390,7 @@ static int on_headers_complete(http_parser *parser)
 	}
 
 	ctx->response->status = parser->status_code;
-	ctx->client->keepalive = http_should_keep_alive(parser);
+	ctx->client->keepalive = git_http_should_keep_alive(parser);
 
 	/* Prepare for authentication */
 	collect_authinfo(&ctx->response->server_auth_schemetypes,
@@ -378,18 +403,28 @@ static int on_headers_complete(http_parser *parser)
 	ctx->response->resend_credentials = resend_needed(ctx->client,
 	                                                  ctx->response);
 
-	/* Stop parsing. */
-	http_parser_pause(parser, 1);
+#ifndef USE_LLHTTP
+	/* Stop parsing. llhttp documentation says about llhttp_pause():
+	 * "Do not call this from user callbacks! User callbacks must
+	 * return HPE_PAUSED if pausing is required", so that's what
+	 * we will do, and call git_http_parser_pause() only for
+	 * http-parser. */
+	git_http_parser_pause(parser);
+#endif
 
 	if (ctx->response->content_type || ctx->response->chunked)
 		ctx->client->state = READING_BODY;
 	else
 		ctx->client->state = DONE;
 
+#ifdef USE_LLHTTP
+	return HPE_PAUSED;
+#else
 	return 0;
+#endif
 }
 
-static int on_body(http_parser *parser, const char *buf, size_t len)
+static int on_body(http_parser_t *parser, const char *buf, size_t len)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 	size_t max_len;
@@ -411,7 +446,7 @@ static int on_body(http_parser *parser, const char *buf, size_t len)
 	return 0;
 }
 
-static int on_message_complete(http_parser *parser)
+static int on_message_complete(http_parser_t *parser)
 {
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 
@@ -878,7 +913,7 @@ GIT_INLINE(int) server_setup_from_url(
 
 static void reset_parser(git_http_client *client)
 {
-	http_parser_init(&client->parser, HTTP_RESPONSE);
+	git_http_parser_init(&client->parser);
 }
 
 static int setup_hosts(
@@ -1122,9 +1157,46 @@ GIT_INLINE(int) client_read(git_http_client *client)
 }
 
 static bool parser_settings_initialized;
-static http_parser_settings parser_settings;
+static http_settings_t parser_settings;
 
-GIT_INLINE(http_parser_settings *) http_client_parser_settings(void)
+static size_t git_http_parser_execute(http_parser_t *parser, const char* data, size_t len)
+{
+#ifdef USE_LLHTTP
+	llhttp_errno_t error;
+	size_t parsed_len;
+
+	/*
+	 * Unlike http_parser, which returns the number of parsed
+	 * bytes in the _execute() call, llhttp returns an error
+	 * code.
+	 */
+
+	if (data == NULL || len == 0) {
+		error = llhttp_finish(parser);
+	} else {
+		error = llhttp_execute(parser, data, len);
+	}
+
+	parsed_len = len;
+	/*
+	 * Adjust number of parsed bytes in case of error.
+	 */
+	if (error != HPE_OK) {
+		parsed_len = llhttp_get_error_pos(parser) - data;
+
+		/* This isn't a real pause, just a way to stop parsing early. */
+		if (error == HPE_PAUSED_UPGRADE) {
+			llhttp_resume_after_upgrade(parser);
+		}
+	}
+
+	return parsed_len;
+#else
+	return http_parser_execute(parser, http_client_parser_settings(), data, len);
+#endif
+}
+
+GIT_INLINE(http_settings_t *) http_client_parser_settings(void)
 {
 	if (!parser_settings_initialized) {
 		parser_settings.on_header_field = on_header_field;
@@ -1141,7 +1213,7 @@ GIT_INLINE(http_parser_settings *) http_client_parser_settings(void)
 
 GIT_INLINE(int) client_read_and_parse(git_http_client *client)
 {
-	http_parser *parser = &client->parser;
+	http_parser_t *parser = &client->parser;
 	http_parser_context *ctx = (http_parser_context *) parser->data;
 	unsigned char http_errno;
 	int read_len;
@@ -1155,11 +1227,10 @@ GIT_INLINE(int) client_read_and_parse(git_http_client *client)
 	if (!client->read_buf.size && (read_len = client_read(client)) < 0)
 		return read_len;
 
-	parsed_len = http_parser_execute(parser,
-		http_client_parser_settings(),
+	parsed_len = git_http_parser_execute(parser,
 		client->read_buf.ptr,
 		client->read_buf.size);
-	http_errno = client->parser.http_errno;
+	http_errno = git_http_parser_errno(client->parser);
 
 	if (parsed_len > INT_MAX) {
 		git_error_set(GIT_ERROR_HTTP, "unexpectedly large parse");
@@ -1179,6 +1250,7 @@ GIT_INLINE(int) client_read_and_parse(git_http_client *client)
 	 * where the server gives you a 100 and 200 simultaneously.)
 	 */
 	if (http_errno == HPE_PAUSED) {
+#ifndef USE_LLHTTP
 		/*
 		 * http-parser has a "feature" where it will not deliver the
 		 * final byte when paused in a callback.  Consume that byte.
@@ -1186,18 +1258,20 @@ GIT_INLINE(int) client_read_and_parse(git_http_client *client)
 		 */
 		GIT_ASSERT(client->read_buf.size > parsed_len);
 
-		http_parser_pause(parser, 0);
+#endif
+		git_http_parser_resume(parser);
 
-		parsed_len += http_parser_execute(parser,
-			http_client_parser_settings(),
+#ifndef USE_LLHTTP
+		parsed_len += git_http_parser_execute(parser,
 			client->read_buf.ptr + parsed_len,
 			1);
+#endif
 	}
 
 	/* Most failures will be reported in http_errno */
-	else if (parser->http_errno != HPE_OK) {
+	else if (git_http_parser_errno(client->parser) != HPE_OK) {
 		git_error_set(GIT_ERROR_HTTP, "http parser error: %s",
-		              http_errno_description(http_errno));
+		              git_http_errno_description(parser, http_errno));
 		return -1;
 	}
 
@@ -1205,7 +1279,7 @@ GIT_INLINE(int) client_read_and_parse(git_http_client *client)
 	else if (parsed_len != client->read_buf.size) {
 		git_error_set(GIT_ERROR_HTTP,
 		              "http parser did not consume entire buffer: %s",
-			      http_errno_description(http_errno));
+			          git_http_errno_description(parser, http_errno));
 		return -1;
 	}
 
diff --git a/src/util/net.c b/src/util/net.c
index 447456451..dede784cc 100644
--- a/src/util/net.c
+++ b/src/util/net.c
@@ -11,7 +11,6 @@
 
 #include "posix.h"
 #include "str.h"
-#include "http_parser.h"
 #include "runtime.h"
 
 #define DEFAULT_PORT_HTTP  "80"