Index: llvm/include/llvm/Support/HTTPServer.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Support/HTTPServer.h
@@ -0,0 +1,49 @@
+#ifndef LLVM_SUPPORT_HTTP_SERVER_H
+#define LLVM_SUPPORT_HTTP_SERVER_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Error.h"
+
+#ifdef LLVM_ENABLE_CPP_HTTPLIB
+#include "httplib.h"
+#endif
+
+namespace llvm {
+
+struct HTTPResponse {
+  unsigned Code;
+  std::string ContentType;
+  std::string Body;
+};
+
+typedef std::function<HTTPResponse(StringRef /*UrlPath*/)> HTTPRequestHandler;
+
+typedef std::function<std::string(size_t /*Offset*/, size_t /*Length*/)>
+    HTTPContentProvider;
+
+struct StreamingHTTPResponse {
+  unsigned StatusCode;
+  std::string ContentType;
+  HTTPContentProvider Provider;
+};
+
+typedef std::function<StreamingHTTPResponse(StringRef)>
+    StreamingHTTPRequestHandler;
+
+class HTTPServer {
+#ifdef LLVM_ENABLE_CPP_HTTPLIB
+  httplib::Server Server;
+  unsigned Port = 0;
+#endif
+public:
+  static bool isAvailable();
+  HTTPServer(HTTPRequestHandler Handler);
+  HTTPServer(StreamingHTTPRequestHandler Handler);
+  Error bind(unsigned Port, StringRef HostInterface = "0.0.0.0");
+  Expected<unsigned> bindAny(StringRef HostInterface = "0.0.0.0");
+  Error listen();
+  void stop();
+};
+} // end namespace llvm
+
+#endif // LLVM_SUPPORT_HTTP_SERVER_H
Index: llvm/lib/Support/CMakeLists.txt
===================================================================
--- llvm/lib/Support/CMakeLists.txt
+++ llvm/lib/Support/CMakeLists.txt
@@ -161,6 +161,7 @@
   GraphWriter.cpp
   Hashing.cpp
   HTTPClient.cpp
+  HTTPServer.cpp
   InitLLVM.cpp
   InstructionCost.cpp
   IntEqClasses.cpp
Index: llvm/lib/Support/HTTPServer.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Support/HTTPServer.cpp
@@ -0,0 +1,72 @@
+#include "llvm/Support/HTTPServer.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
+
+using namespace llvm;
+
+#ifdef LLVM_ENABLE_CPP_HTTPLIB
+
+bool HTTPServer::isAvailable() { return true; }
+
+HTTPServer::HTTPServer(
+    std::function<StreamingHTTPResponse(StringRef)> StreamingRequestHandler) {
+  llvm_unreachable("unimplemented");
+}
+
+HTTPServer::HTTPServer(std::function<HTTPResponse(StringRef)> RequestHandler) {
+  Server.Get(R"(/(.*))",
+             [&](const httplib::Request &Request, httplib::Response &Response) {
+               SmallString<64> UrlPath;
+               UrlPath = std::string(Request.matches[1]);
+               HTTPResponse Resp = RequestHandler(UrlPath);
+               Response.set_content(Resp.Body.data(), Resp.ContentType.data());
+               return Response.status = Resp.Code;
+             });
+}
+
+Error HTTPServer::bind(unsigned ListenPort, StringRef HostInterface) {
+  SmallString<16> HostInterfaceStorage;
+  StringRef S =
+      Twine(HostInterface).toNullTerminatedStringRef(HostInterfaceStorage);
+
+  if (!Server.bind_to_port(S.begin(), ListenPort))
+    return createStringError(errc::io_error,
+                             "Could not assign requested address.");
+
+  Port = ListenPort;
+  return Error::success();
+}
+
+Expected<unsigned> HTTPServer::bindAny(StringRef HostInterface) {
+  SmallString<16> HostInterfaceStorage;
+  StringRef S =
+      Twine(HostInterface).toNullTerminatedStringRef(HostInterfaceStorage);
+
+  int ListenPort = Server.bind_to_any_port(S.begin());
+  if (ListenPort < 0)
+    return createStringError(errc::io_error,
+                             "Could not assign any port on requested address.");
+  return Port = ListenPort;
+}
+
+Error HTTPServer::listen() {
+  if (Port)
+    Server.listen_after_bind();
+  return Error::success();
+}
+
+void HTTPServer::stop() { Server.stop(); }
+
+#else
+
+// TODO: Implement barebones standalone HTTP server implementation.
+bool HTTPServer::isAvailable() { return false; }
+
+HTTPServer::HTTPServer(
+    std::function<StreamingHTTPResponse(StringRef)> StreamingRequestHandler) {
+  llvm_unreachable(
+      "Attempt to instantiate HTTPServer when no implementation is available.");
+}
+#endif
Index: llvm/unittests/Support/CMakeLists.txt
===================================================================
--- llvm/unittests/Support/CMakeLists.txt
+++ llvm/unittests/Support/CMakeLists.txt
@@ -42,6 +42,7 @@
   HashBuilderTest.cpp
   Host.cpp
   HTTPClient.cpp
+  HTTPServer.cpp
   IndexedAccessorTest.cpp
   InstructionCostTest.cpp
   ItaniumManglingCanonicalizerTest.cpp
Index: llvm/unittests/Support/HTTPServer.cpp
===================================================================
--- /dev/null
+++ llvm/unittests/Support/HTTPServer.cpp
@@ -0,0 +1,55 @@
+//===-- llvm/unittest/Support/HTTPClient.cpp - unit tests -------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/HTTPServer.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/HTTPClient.h"
+#include "llvm/Support/ThreadPool.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+#ifdef LLVM_ENABLE_CPP_HTTPLIB
+
+TEST(HTTPServer, isAvailable) { EXPECT_TRUE(HTTPServer::isAvailable()); }
+
+HTTPResponse SimpleResponse = {200u, "text/plain", "hello, world\n"};
+HTTPRequestHandler SimpleHandler = [](StringRef UrlPath) -> HTTPResponse {
+  return SimpleResponse;
+};
+
+TEST(HTTPServer, bindAny) {
+  // test that we can bind to any address
+  HTTPServer Server(SimpleHandler);
+  EXPECT_THAT_EXPECTED(Server.bindAny(), Succeeded());
+}
+
+#ifdef LLVM_ENABLE_CURL
+
+// Test the client and server against each other.
+TEST(HTTPClientServer, HTTPClientServerHello) {
+  HTTPServer Server(SimpleHandler);
+  Expected<unsigned> PortOrErr = Server.bindAny();
+  EXPECT_THAT_EXPECTED(PortOrErr, Succeeded());
+  unsigned &Port = *PortOrErr;
+  ThreadPool Pool(hardware_concurrency(1));
+  Pool.async([&]() { EXPECT_THAT_ERROR(Server.listen(), Succeeded()); });
+  std::string Url = "http://localhost:" + utostr(Port);
+  HTTPClient::initialize();
+  Expected<HTTPResponseBuffer> BufferOrErr = HTTPClient().get(Url);
+  EXPECT_THAT_EXPECTED(BufferOrErr, Succeeded());
+  HTTPResponseBuffer &Buffer = *BufferOrErr;
+  EXPECT_EQ(Buffer.Code, SimpleResponse.Code);
+  EXPECT_EQ(Buffer.Body->MemoryBuffer::getBuffer(), SimpleResponse.Body);
+  Server.stop();
+}
+
+#endif
+
+#endif