diff --git a/lib/Server.js b/lib/Server.js
index ff21ccee94..b69663c4d1 100644
--- a/lib/Server.js
+++ b/lib/Server.js
@@ -33,6 +33,7 @@ const historyApiFallback = require('connect-history-api-fallback');
 const webpack = require('webpack');
 const webpackDevMiddleware = require('webpack-dev-middleware');
 
+const updateCompiler = require('./utils/updateCompiler');
 const createLogger = require('./utils/createLogger');
 const createCertificate = require('./utils/createCertificate');
 
@@ -89,6 +90,8 @@ class Server {
       throw new Error("'filename' option must be set in lazy mode.");
     }
 
+    updateCompiler(compiler, options);
+
     this.stats =
       options.stats && Object.keys(options.stats).length
         ? options.stats
diff --git a/lib/utils/addEntries.js b/lib/utils/addEntries.js
index f4aa210b39..a4d28d9830 100644
--- a/lib/utils/addEntries.js
+++ b/lib/utils/addEntries.js
@@ -8,6 +8,7 @@ function addEntries(config, options, server) {
     // we're stubbing the app in this method as it's static and doesn't require
     // a server to be supplied. createDomain requires an app with the
     // address() signature.
+
     const app = server || {
       address() {
         return { port: options.port };
@@ -35,13 +36,22 @@ function addEntries(config, options, server) {
         const clone = {};
 
         Object.keys(entry).forEach((key) => {
-          clone[key] = entries.concat(entry[key]);
+          // entry[key] should be a string here
+          clone[key] = prependEntry(entry[key]);
         });
 
         return clone;
       }
 
-      return entries.concat(entry);
+      // in this case, entry is a string or an array.
+      // make sure that we do not add duplicates.
+      const entriesClone = entries.slice(0);
+      [].concat(entry).forEach((newEntry) => {
+        if (!entriesClone.includes(newEntry)) {
+          entriesClone.push(newEntry);
+        }
+      });
+      return entriesClone;
     };
 
     // eslint-disable-next-line no-shadow
diff --git a/lib/utils/updateCompiler.js b/lib/utils/updateCompiler.js
new file mode 100644
index 0000000000..4f6619874a
--- /dev/null
+++ b/lib/utils/updateCompiler.js
@@ -0,0 +1,67 @@
+'use strict';
+
+/* eslint-disable
+  no-shadow,
+  no-undefined
+*/
+const webpack = require('webpack');
+const addEntries = require('./addEntries');
+
+function updateCompiler(compiler, options) {
+  if (options.inline !== false) {
+    const findHMRPlugin = (config) => {
+      if (!config.plugins) {
+        return undefined;
+      }
+
+      return config.plugins.find(
+        (plugin) => plugin.constructor === webpack.HotModuleReplacementPlugin
+      );
+    };
+
+    const compilers = [];
+    const compilersWithoutHMR = [];
+    let webpackConfig;
+    if (compiler.compilers) {
+      webpackConfig = [];
+      compiler.compilers.forEach((compiler) => {
+        webpackConfig.push(compiler.options);
+        compilers.push(compiler);
+        if (!findHMRPlugin(compiler.options)) {
+          compilersWithoutHMR.push(compiler);
+        }
+      });
+    } else {
+      webpackConfig = compiler.options;
+      compilers.push(compiler);
+      if (!findHMRPlugin(compiler.options)) {
+        compilersWithoutHMR.push(compiler);
+      }
+    }
+
+    // it's possible that we should clone the config before doing
+    // this, but it seems safe not to since it actually reflects
+    // the changes we are making to the compiler
+    // important: this relies on the fact that addEntries now
+    // prevents duplicate new entries.
+    addEntries(webpackConfig, options);
+    compilers.forEach((compiler) => {
+      const config = compiler.options;
+      compiler.hooks.entryOption.call(config.context, config.entry);
+    });
+
+    // do not apply the plugin unless it didn't exist before.
+    if (options.hot || options.hotOnly) {
+      compilersWithoutHMR.forEach((compiler) => {
+        // addDevServerEntrypoints above should have added the plugin
+        // to the compiler options
+        const plugin = findHMRPlugin(compiler.options);
+        if (plugin) {
+          plugin.apply(compiler);
+        }
+      });
+    }
+  }
+}
+
+module.exports = updateCompiler;
diff --git a/package-lock.json b/package-lock.json
index ee87d059ce..eb33db2233 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4674,8 +4674,7 @@
         },
         "ansi-regex": {
           "version": "2.1.1",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -4693,13 +4692,11 @@
         },
         "balanced-match": {
           "version": "1.0.0",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
-          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -4712,18 +4709,15 @@
         },
         "code-point-at": {
           "version": "1.1.0",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "concat-map": {
           "version": "0.0.1",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "console-control-strings": {
           "version": "1.1.0",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -4826,8 +4820,7 @@
         },
         "inherits": {
           "version": "2.0.3",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "ini": {
           "version": "1.3.5",
@@ -4837,7 +4830,6 @@
         "is-fullwidth-code-point": {
           "version": "1.0.0",
           "bundled": true,
-          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -4850,20 +4842,17 @@
         "minimatch": {
           "version": "3.0.4",
           "bundled": true,
-          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
         },
         "minimist": {
           "version": "0.0.8",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
-          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -4880,7 +4869,6 @@
         "mkdirp": {
           "version": "0.5.1",
           "bundled": true,
-          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -4953,8 +4941,7 @@
         },
         "number-is-nan": {
           "version": "1.0.1",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -4964,7 +4951,6 @@
         "once": {
           "version": "1.4.0",
           "bundled": true,
-          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -5040,8 +5026,7 @@
         },
         "safe-buffer": {
           "version": "5.1.2",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -5071,7 +5056,6 @@
         "string-width": {
           "version": "1.0.2",
           "bundled": true,
-          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -5089,7 +5073,6 @@
         "strip-ansi": {
           "version": "3.0.1",
           "bundled": true,
-          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -5128,13 +5111,11 @@
         },
         "wrappy": {
           "version": "1.0.2",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         },
         "yallist": {
           "version": "3.0.3",
-          "bundled": true,
-          "optional": true
+          "bundled": true
         }
       }
     },
diff --git a/test/Client.test.js b/test/Client.test.js
index 641d059876..db317eaf07 100644
--- a/test/Client.test.js
+++ b/test/Client.test.js
@@ -3,7 +3,6 @@
 const express = require('express');
 const httpProxy = require('http-proxy-middleware');
 const request = require('supertest');
-const addEntries = require('../lib/utils/addEntries');
 const helper = require('./helper');
 const config = require('./fixtures/client-config/webpack.config');
 const runBrowser = require('./helpers/run-browser');
@@ -28,13 +27,13 @@ describe('Client code', () => {
       port: 9001,
       host: '0.0.0.0',
       disableHostCheck: true,
+      inline: true,
       hot: true,
       watchOptions: {
         poll: true,
       },
     };
-    addEntries(config, options);
-    helper.start(config, options, done);
+    helper.startAwaitingCompilation(config, options, done);
   });
 
   afterAll(helper.close);
@@ -65,8 +64,7 @@ describe('Client code', () => {
             expect(requestObj.url()).toMatch(
               /^http:\/\/localhost:9000\/sockjs-node/
             );
-            browser.close();
-            done();
+            browser.close().then(done);
           });
         page.goto('http://localhost:9000/main');
       });
diff --git a/test/Entry.test.js b/test/Entry.test.js
index b6bbb76732..0cd67d76ce 100644
--- a/test/Entry.test.js
+++ b/test/Entry.test.js
@@ -254,6 +254,21 @@ describe('Entry', () => {
     ]);
   });
 
+  it('can prevent duplicate entries from successive calls', () => {
+    const webpackOptions = Object.assign({}, config);
+    const devServerOptions = { hot: true };
+
+    addEntries(webpackOptions, devServerOptions);
+    addEntries(webpackOptions, devServerOptions);
+
+    expect(webpackOptions.entry.length).toEqual(3);
+
+    const result = webpackOptions.entry.filter((entry) =>
+      normalize(entry).includes('webpack/hot/dev-server')
+    );
+    expect(result.length).toEqual(1);
+  });
+
   it('supports entry as Function', () => {
     const webpackOptions = Object.assign({}, configEntryAsFunction);
     const devServerOptions = {};
diff --git a/test/Hot.test.js b/test/Hot.test.js
new file mode 100644
index 0000000000..5db2b2038b
--- /dev/null
+++ b/test/Hot.test.js
@@ -0,0 +1,246 @@
+'use strict';
+
+const request = require('supertest');
+const helper = require('./helper');
+const config = require('./fixtures/client-config/webpack.config');
+const multiCompilerConfig = require('./fixtures/multi-compiler-config/webpack.config');
+
+describe('Hot Module Replacement (hot/hotOnly options)', () => {
+  let server;
+  let req;
+
+  describe('simple hot config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should include hot script in the bundle', (done) => {
+      req.get('/main.js').expect(200, /webpack\/hot\/dev-server\.js/, done);
+    });
+  });
+
+  describe('simple hotOnly config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        inline: true,
+        hotOnly: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should include hotOnly script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200, /webpack\/hot\/only-dev-server\.js/, done);
+    });
+  });
+
+  describe('multi compiler hot config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(
+        multiCompilerConfig,
+        options,
+        done
+      );
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should include hot script in the bundle', (done) => {
+      req.get('/main.js').expect(200, /webpack\/hot\/dev-server\.js/, done);
+    });
+  });
+
+  describe('hot disabled entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: false,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should NOT include hot script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200)
+        .then(({ text }) => {
+          expect(text).not.toMatch(/webpack\/hot\/dev-server\.js/);
+          done();
+        });
+    });
+  });
+
+  // the following cases check to make sure that the HMR
+  // plugin is actually added
+
+  describe('simple hot config HMR plugin', () => {
+    it('should register the HMR plugin before compilation is complete', (done) => {
+      let pluginFound = false;
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      const fullSetup = helper.startAwaitingCompilationFullSetup(
+        config,
+        options,
+        () => {
+          expect(pluginFound).toBeTruthy();
+          done();
+        }
+      );
+
+      const compiler = fullSetup.compiler;
+      compiler.hooks.compilation.intercept({
+        register: (tapInfo) => {
+          if (tapInfo.name === 'HotModuleReplacementPlugin') {
+            pluginFound = true;
+          }
+          return tapInfo;
+        },
+      });
+    });
+
+    afterAll(helper.close);
+  });
+
+  describe('simple hotOnly config HMR plugin', () => {
+    it('should register the HMR plugin before compilation is complete', (done) => {
+      let pluginFound = false;
+      const options = {
+        port: 9000,
+        inline: true,
+        hotOnly: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      const fullSetup = helper.startAwaitingCompilationFullSetup(
+        config,
+        options,
+        () => {
+          expect(pluginFound).toBeTruthy();
+          done();
+        }
+      );
+
+      const compiler = fullSetup.compiler;
+      compiler.hooks.compilation.intercept({
+        register: (tapInfo) => {
+          if (tapInfo.name === 'HotModuleReplacementPlugin') {
+            pluginFound = true;
+          }
+          return tapInfo;
+        },
+      });
+    });
+
+    afterAll(helper.close);
+  });
+
+  describe('multi compiler hot config HMR plugin', () => {
+    it('should register the HMR plugin before compilation is complete', (done) => {
+      let pluginFound = false;
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      const fullSetup = helper.startAwaitingCompilationFullSetup(
+        multiCompilerConfig,
+        options,
+        () => {
+          expect(pluginFound).toBeTruthy();
+          done();
+        }
+      );
+
+      const compiler = fullSetup.compiler.compilers[0];
+      compiler.hooks.compilation.intercept({
+        register: (tapInfo) => {
+          if (tapInfo.name === 'HotModuleReplacementPlugin') {
+            pluginFound = true;
+          }
+          return tapInfo;
+        },
+      });
+    });
+
+    afterAll(helper.close);
+  });
+
+  describe('hot disabled HMR plugin', () => {
+    it('should NOT register the HMR plugin before compilation is complete', (done) => {
+      let pluginFound = false;
+      const options = {
+        port: 9000,
+        inline: true,
+        hot: false,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      const fullSetup = helper.startAwaitingCompilationFullSetup(
+        config,
+        options,
+        () => {
+          expect(pluginFound).toBeFalsy();
+          done();
+        }
+      );
+
+      const compiler = fullSetup.compiler;
+      compiler.hooks.compilation.intercept({
+        register: (tapInfo) => {
+          if (tapInfo.name === 'HotModuleReplacementPlugin') {
+            pluginFound = true;
+          }
+          return tapInfo;
+        },
+      });
+    });
+
+    afterAll(helper.close);
+  });
+});
diff --git a/test/Inline.test.js b/test/Inline.test.js
new file mode 100644
index 0000000000..948e2710b0
--- /dev/null
+++ b/test/Inline.test.js
@@ -0,0 +1,90 @@
+'use strict';
+
+const request = require('supertest');
+const helper = require('./helper');
+const config = require('./fixtures/client-config/webpack.config');
+const multiCompilerConfig = require('./fixtures/multi-compiler-config/webpack.config');
+
+describe('inline', () => {
+  let server;
+  let req;
+
+  describe('simple inline config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        host: '0.0.0.0',
+        inline: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should include inline client script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200, /client\/index\.js\?http:\/\/0\.0\.0\.0:9000/, done);
+    });
+  });
+
+  describe('multi compiler inline config entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        host: '0.0.0.0',
+        inline: true,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(
+        multiCompilerConfig,
+        options,
+        done
+      );
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should include inline client script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200, /client\/index\.js\?http:\/\/0\.0\.0\.0:9000/, done);
+    });
+  });
+
+  describe('inline disabled entries', () => {
+    beforeAll((done) => {
+      const options = {
+        port: 9000,
+        host: '0.0.0.0',
+        inline: false,
+        watchOptions: {
+          poll: true,
+        },
+      };
+      server = helper.startAwaitingCompilation(config, options, done);
+      req = request(server.app);
+    });
+
+    afterAll(helper.close);
+
+    it('should NOT include inline client script in the bundle', (done) => {
+      req
+        .get('/main.js')
+        .expect(200)
+        .then(({ text }) => {
+          expect(text).not.toMatch(
+            /client\/index\.js\?http:\/\/0\.0\.0\.0:9000/
+          );
+          done();
+        });
+    });
+  });
+});
diff --git a/test/Lazy.test.js b/test/Lazy.test.js
index 21d733ceb1..c64487a8b4 100644
--- a/test/Lazy.test.js
+++ b/test/Lazy.test.js
@@ -15,7 +15,7 @@ describe('Lazy', () => {
   });
 
   it('with filename option should not throw an error', (done) => {
-    helper.start(
+    helper.startBeforeCompilation(
       config,
       {
         lazy: true,
diff --git a/test/helper.js b/test/helper.js
index 412652cdaa..e45144f9d3 100644
--- a/test/helper.js
+++ b/test/helper.js
@@ -1,5 +1,8 @@
 'use strict';
 
+/* eslint-disable
+  no-undefined
+*/
 const webpack = require('webpack');
 const Server = require('../lib/Server');
 
@@ -9,10 +12,26 @@ module.exports = {
   // start server, returning the full setup of the server
   // (both the server and the compiler)
   startFullSetup(config, options, done) {
-    // eslint-disable-next-line no-undefined
     if (options.quiet === undefined) {
       options.quiet = true;
     }
+    // originally, inline was not working by default for tests with the API
+    // if you need to test inline, it should be set explicitly,
+    // rather than expecting it to be defaulted to
+    // (the only test that relied on inline before this point was Client.test.js)
+    if (
+      options.inline === undefined &&
+      options.hot === undefined &&
+      options.hotOnly === undefined
+    ) {
+      options.inline = false;
+    }
+    // defaulting to this will hopefully help with problems on OSX in tests
+    if (options.watchOptions === undefined) {
+      options.watchOptions = {
+        poll: true,
+      };
+    }
     const compiler = webpack(config);
     server = new Server(compiler, options);
 
@@ -28,7 +47,7 @@ module.exports = {
       compiler,
     };
   },
-  startAwaitingCompilation(config, options, done) {
+  startAwaitingCompilationFullSetup(config, options, done) {
     let readyCount = 0;
     const ready = () => {
       readyCount += 1;
@@ -41,9 +60,21 @@ module.exports = {
     // wait for compilation, since dev server can start before this
     // https://github.com/webpack/webpack-dev-server/issues/847
     fullSetup.compiler.hooks.done.tap('done', ready);
-    return fullSetup.server;
+    return fullSetup;
+  },
+  startAwaitingCompilation(config, options, done) {
+    return this.startAwaitingCompilationFullSetup(config, options, done).server;
   },
   start(config, options, done) {
+    // I suspect that almost all tests need to wait for compilation to
+    // finish, because not doing so leaves open handles for jest,
+    // in the case where a compilation didn't finish before destroying
+    // the server and moving on. Thus, the default "start" should wait
+    // for compilation, and only special cases where you don't expect
+    // a compilation happen should use startBeforeCompilation
+    return this.startAwaitingCompilation(config, options, done);
+  },
+  startBeforeCompilation(config, options, done) {
     return this.startFullSetup(config, options, done).server;
   },
   close(done) {