diff --git a/packages/serve/__tests__/createConfig.test.ts b/packages/serve/__tests__/createConfig.test.ts
deleted file mode 100644
index 199df84b4a1..00000000000
--- a/packages/serve/__tests__/createConfig.test.ts
+++ /dev/null
@@ -1,53 +0,0 @@
-'use strict';
-
-import createConfig from '../src/createConfig';
-
-describe('createConfig', () => {
-    it('creates config with arguments', () => {
-        const args = {
-            hot: true,
-            openPage: 'main',
-        };
-        expect(createConfig(args, false)).toEqual(args);
-    });
-
-    it('sets client object using clientLogging argument', () => {
-        const args = {
-            clientLogging: 'verbose',
-        };
-        expect(createConfig(args, false)).toEqual({
-            client: {
-                logging: 'verbose',
-            },
-        });
-    });
-
-    it('sets hot using hotOnly argument', () => {
-        const args = {
-            hotOnly: true,
-        };
-        expect(createConfig(args, false)).toEqual({
-            hotOnly: true,
-        });
-    });
-
-    it('sets hot using hotOnly argument with devServer 4', () => {
-        const args = {
-            hotOnly: true,
-        };
-        expect(createConfig(args, true)).toEqual({
-            hot: 'only',
-        });
-    });
-
-    it('overrides hot with hotOnly', () => {
-        const args = {
-            hot: true,
-            hotOnly: true,
-        };
-        expect(createConfig(args, false)).toEqual({
-            hot: true,
-            hotOnly: true,
-        });
-    });
-});
diff --git a/packages/serve/src/createConfig.ts b/packages/serve/src/createConfig.ts
deleted file mode 100644
index 0c60ccf6099..00000000000
--- a/packages/serve/src/createConfig.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-import { devServerOptionsType } from './types';
-
-/**
- *
- * Creates a devServer config from CLI args
- *
- * @param {Object} args - devServer args
- * @param {boolean} isDevServer4 - is devServer v4
- *
- * @returns {Object} valid devServer options object
- */
-export default function createConfig(args, isDevServer4): devServerOptionsType {
-    const options = { ...args };
-
-    if (options.clientLogging) {
-        options.client = {
-            logging: options.clientLogging,
-        };
-        // clientLogging is not a valid devServer option
-        delete options.clientLogging;
-    }
-    if (isDevServer4 && options.hotOnly) {
-        options.hot = 'only';
-        // hotOnly is not a valid devServer option
-        delete options.hotOnly;
-    }
-
-    return options;
-}
diff --git a/packages/serve/src/startDevServer.ts b/packages/serve/src/startDevServer.ts
index 945f74a45a1..5c372888435 100644
--- a/packages/serve/src/startDevServer.ts
+++ b/packages/serve/src/startDevServer.ts
@@ -1,6 +1,5 @@
 import { utils } from 'webpack-cli';
 
-import createConfig from './createConfig';
 import getDevServerOptions from './getDevServerOptions';
 import mergeOptions from './mergeOptions';
 
@@ -15,7 +14,7 @@ const { logger } = utils;
  *
  * @returns {Object[]} array of resulting servers
  */
-export default function startDevServer(compiler, devServerArgs): object[] {
+export default function startDevServer(compiler, cliOptions): object[] {
     let isDevServer4 = false,
         devServerVersion,
         Server;
@@ -30,7 +29,6 @@ export default function startDevServer(compiler, devServerArgs): object[] {
     }
     isDevServer4 = devServerVersion.startsWith('4');
 
-    const cliOptions = createConfig(devServerArgs, isDevServer4);
     const devServerOptions = getDevServerOptions(compiler);
 
     const servers = [];
diff --git a/packages/webpack-cli/__tests__/arg-parser.test.js b/packages/webpack-cli/__tests__/arg-parser.test.js
index f61aab4d3a3..60dc543030d 100644
--- a/packages/webpack-cli/__tests__/arg-parser.test.js
+++ b/packages/webpack-cli/__tests__/arg-parser.test.js
@@ -96,6 +96,16 @@ const basicOptions = [
         multiple: true,
         description: 'multi flag',
     },
+    {
+        name: 'processor-flag',
+        usage: '--processor-flag',
+        type: Boolean,
+        description: 'flag with processor',
+        processor(opts) {
+            opts.processed = opts.processorFlag;
+            delete opts.processorFlag;
+        },
+    },
 ];
 
 const helpAndVersionOptions = basicOptions.slice(0);
@@ -421,4 +431,14 @@ describe('arg-parser', () => {
         });
         expect(warnMock.mock.calls.length).toEqual(0);
     });
+
+    it('parses --processor-flag', () => {
+        const res = argParser(basicOptions, ['--processor-flag'], true);
+        expect(res.unknownArgs.length).toEqual(0);
+        expect(res.opts).toEqual({
+            processed: true,
+            stringFlagWithDefault: 'default-value',
+        });
+        expect(warnMock.mock.calls.length).toEqual(0);
+    });
 });
diff --git a/packages/webpack-cli/lib/utils/arg-parser.js b/packages/webpack-cli/lib/utils/arg-parser.js
index 7cbab371fa3..708ff698b28 100644
--- a/packages/webpack-cli/lib/utils/arg-parser.js
+++ b/packages/webpack-cli/lib/utils/arg-parser.js
@@ -28,6 +28,7 @@ const argParser = (options, args, argsOnly = false, name = '') => {
     }
 
     const parser = new commander.Command();
+    const processors = {};
 
     // Set parser name
     parser.name(name);
@@ -151,6 +152,15 @@ const argParser = (options, args, argsOnly = false, name = '') => {
             parserInstance.option(negatedFlag, `negates ${option.name}`).action(() => {});
         }
 
+        if (option.processor) {
+            // camel-case
+            const attributeName = option.name.split('-').reduce((str, word) => {
+                return str + word[0].toUpperCase() + word.slice(1);
+            });
+
+            processors[attributeName] = option.processor;
+        }
+
         return parserInstance;
     }, parser);
 
@@ -192,6 +202,8 @@ const argParser = (options, args, argsOnly = false, name = '') => {
     Object.keys(opts).forEach((key) => {
         if (opts[key] === undefined) {
             delete opts[key];
+        } else if (processors[key]) {
+            processors[key](opts);
         }
     });