diff --git a/src/cli/parse-flags.ts b/src/cli/parse-flags.ts
index c2db1af329b..cfcc6b89b28 100644
--- a/src/cli/parse-flags.ts
+++ b/src/cli/parse-flags.ts
@@ -51,9 +51,13 @@ export const parseFlags = (args: string[], sys?: CompilerSystem): ConfigFlags =>
     }
   }
 
-  flags.unknownArgs = flags.args.filter((arg: string) => {
-    return !flags.knownArgs.includes(arg);
-  });
+  // to find unknown / unrecognized arguments we filter `args`, including only
+  // arguments whose normalized form is not found in `knownArgs`. `knownArgs`
+  // is populated during the call to `parseArgs` above. For arguments like
+  // `--foobar` the string `"--foobar"` will be added, while for more
+  // complicated arguments like `--bizBoz=bop` or `--bizBoz bop` just the
+  // string `"--bizBoz"` will be added.
+  flags.unknownArgs = flags.args.filter((arg: string) => !flags.knownArgs.includes(parseEqualsArg(arg)[0]));
 
   return flags;
 };
@@ -259,17 +263,18 @@ const getValue = (
 
   let value: string | undefined;
   let matchingArg: string | undefined;
+
   args.forEach((arg, i) => {
     if (arg.startsWith(`--${dashCaseName}=`) || arg.startsWith(`--${configCaseName}=`)) {
-      value = getEqualsValue(arg);
-      matchingArg = arg;
+      // our argument was passed at the command-line in the format --argName=arg-value
+      [matchingArg, value] = parseEqualsArg(arg);
     } else if (arg === `--${dashCaseName}` || arg === `--${configCaseName}`) {
+      // the next value in the array is assumed to be a value for this argument
       value = args[i + 1];
       matchingArg = arg;
     } else if (alias) {
       if (arg.startsWith(`-${alias}=`)) {
-        value = getEqualsValue(arg);
-        matchingArg = arg;
+        [matchingArg, value] = parseEqualsArg(arg);
       } else if (arg === `-${alias}`) {
         value = args[i + 1];
         matchingArg = arg;
@@ -287,13 +292,43 @@ interface CLIArgValue {
 }
 
 /**
- * When a parameter is set in the format `--foobar=12` at the CLI (as opposed to
- * `--foobar 12`) we want to get the value after the `=` sign
+ * Parse an 'equals' argument, which is a CLI argument-value pair in the
+ * format `--foobar=12` (as opposed to the space-separated format `--foobar
+ * 12`).
+ *
+ * To parse this we split on the `=`, returning the first part as the argument
+ * name and the second part as the value. We join the value on `"="` in case
+ * there is another `"="` in the argument.
+ *
+ * This function is safe to call with any arg, and can therefore be used as
+ * an argument 'normalizer'. If CLI argument is not an 'equals' argument then
+ * the return value will be a tuple of the original argument and an empty
+ * string `""` for the value.
+ *
+ * In code terms, if you do:
  *
- * @param commandArgument the arg in question
- * @returns the value after the `=`
+ * ```ts
+ * const [arg, value] = parseEqualsArg("--myArgument")
+ * ```
+ *
+ * Then `arg` will be `"--myArgument"` and `value` will be `""`, whereas if
+ * you do:
+ *
+ *
+ * ```ts
+ * const [arg, value] = parseEqualsArg("--myArgument=myValue")
+ * ```
+ *
+ * Then `arg` will be `"--myArgument"` and `value` will be `"myValue"`.
+ *
+ * @param arg the arg in question
+ * @returns a tuple containing the arg name and the value (if present)
  */
-const getEqualsValue = (commandArgument: string) => commandArgument.split('=').slice(1).join('=');
+export const parseEqualsArg = (arg: string): [string, string] => {
+  const [originalArg, ...value] = arg.split('=');
+
+  return [originalArg, value.join('=')];
+};
 
 /**
  * Small helper for getting type-system-level assurance that a `string` can be
diff --git a/src/cli/test/parse-flags.spec.ts b/src/cli/test/parse-flags.spec.ts
index f63018b4805..df44abda4ee 100644
--- a/src/cli/test/parse-flags.spec.ts
+++ b/src/cli/test/parse-flags.spec.ts
@@ -1,7 +1,7 @@
 import type * as d from '../../declarations';
 import { LogLevel } from '../../declarations';
 import { BOOLEAN_CLI_ARGS, STRING_CLI_ARGS, NUMBER_CLI_ARGS } from '../config-flags';
-import { parseFlags } from '../parse-flags';
+import { parseEqualsArg, parseFlags } from '../parse-flags';
 
 describe('parseFlags', () => {
   let args: string[] = [];
@@ -190,12 +190,21 @@ describe('parseFlags', () => {
   it.each(STRING_CLI_ARGS)('should parse string flag %s', (cliArg) => {
     const flags = parseFlags([`--${cliArg}`, 'test-value'], sys);
     expect(flags.knownArgs).toEqual([`--${cliArg}`, 'test-value']);
+    expect(flags.unknownArgs).toEqual([])
     expect(flags[cliArg]).toBe('test-value');
   });
 
+  it.each(STRING_CLI_ARGS)('should parse string flag --%s=value', (cliArg) => {
+    const flags = parseFlags([`--${cliArg}=path/to/file.js`], sys);
+    expect(flags.knownArgs).toEqual([`--${cliArg}`, 'path/to/file.js']);
+    expect(flags.unknownArgs).toEqual([])
+    expect(flags[cliArg]).toBe('path/to/file.js');
+  });
+
   it.each(NUMBER_CLI_ARGS)('should parse number flag %s', (cliArg) => {
     const flags = parseFlags([`--${cliArg}`, '42'], sys);
     expect(flags.knownArgs).toEqual([`--${cliArg}`, '42']);
+    expect(flags.unknownArgs).toEqual([])
     expect(flags[cliArg]).toBe(42);
   });
 
@@ -203,6 +212,7 @@ describe('parseFlags', () => {
     args[0] = '--compare';
     const flags = parseFlags(args, sys);
     expect(flags.knownArgs).toEqual(['--compare']);
+    expect(flags.unknownArgs).toEqual([])
     expect(flags.compare).toBe(true);
   });
 
@@ -574,4 +584,18 @@ describe('parseFlags', () => {
     expect(flags.help).toBe(true);
     expect(flags.config).toBe('./myconfig.json');
   });
+
+  describe('parseEqualsArg', () => {
+    it.each([
+      ['--fooBar=baz', '--fooBar', 'baz'],
+      ['--foo-bar=4', '--foo-bar', '4'],
+      ['--fooBar=twenty=3*4', '--fooBar', 'twenty=3*4'],
+      ['--fooBar', '--fooBar', ''],
+      ['--foo-bar', '--foo-bar', ''],
+    ])('should parse %s correctly', (testArg, expectedArg, expectedValue) => {
+      const [arg, value] = parseEqualsArg(testArg);
+      expect(arg).toBe(expectedArg);
+      expect(value).toBe(expectedValue);
+    });
+  });
 });
diff --git a/src/testing/jest/test/jest-config.spec.ts b/src/testing/jest/test/jest-config.spec.ts
index ed4672fe95a..71c7e722fa7 100644
--- a/src/testing/jest/test/jest-config.spec.ts
+++ b/src/testing/jest/test/jest-config.spec.ts
@@ -19,6 +19,17 @@ describe('jest-config', () => {
     expect(jestArgv.maxWorkers).toBe(2);
   });
 
+  it('should pass --outputFile=path/to/file', () => {
+    const args = ['test', '--ci', '--outputFile=path/to/my-file'];
+    const config = mockValidatedConfig();
+    config.flags = parseFlags(args, config.sys);
+    expect(config.flags.args).toEqual(['--ci', '--outputFile=path/to/my-file']);
+    expect(config.flags.unknownArgs).toEqual([]);
+    config.testing = {};
+    const jestArgv = buildJestArgv(config);
+    expect(jestArgv.outputFile).toBe('path/to/my-file');
+  });
+
   it('pass --maxWorkers=2 arg when e2e test and --ci', () => {
     const args = ['test', '--ci', '--e2e', '--max-workers=2'];
     const config = mockValidatedConfig();