diff --git a/lib/command.js b/lib/command.js
index 3cfc3ba32..d904cfb00 100644
--- a/lib/command.js
+++ b/lib/command.js
@@ -57,6 +57,16 @@ class Command extends EventEmitter {
     this._showHelpAfterError = false;
     this._showSuggestionAfterError = true;
 
+    this._strictPriority = false;
+    this._priorities = [
+      'cli',
+      'env',
+      'config', // placeholder for configuration files
+      'implied', // implied by others configs
+      'default', // default option value
+      undefined // initial state, not touched yet
+    ];
+
     // see .configureOutput() for docs
     this._outputConfiguration = {
       writeOut: (str) => process.stdout.write(str),
@@ -105,6 +115,8 @@ class Command extends EventEmitter {
     this._enablePositionalOptions = sourceCommand._enablePositionalOptions;
     this._showHelpAfterError = sourceCommand._showHelpAfterError;
     this._showSuggestionAfterError = sourceCommand._showSuggestionAfterError;
+    this._strictPriority = sourceCommand._strictPriority;
+    this._priorities = sourceCommand._priorities;
 
     return this;
   }
@@ -412,6 +424,11 @@ Expecting one of '${allowedValues.join("', '")}'`);
     return this;
   }
 
+  strictPriority() {
+    this._strictPriority = true;
+    return this;
+  }
+
   /**
    * Register callback to use as replacement for calling process.exit.
    *
@@ -780,11 +797,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
    */
 
   setOptionValue(key, value) {
-    if (this._storeOptionsAsProperties) {
-      this[key] = value;
-    } else {
-      this._optionValues[key] = value;
-    }
+    this.setOptionValueWithSource(key, value);
     return this;
   }
 
@@ -797,8 +810,13 @@ Expecting one of '${allowedValues.join("', '")}'`);
     * @return {Command} `this` command for chaining
     */
 
-  setOptionValueWithSource(key, value, source) {
-    this.setOptionValue(key, value);
+  setOptionValueWithSource(key, value, source = null) {
+    if (this._strictPriority && !this._isNewSourcePreferred(source, this.getOptionValueSource(key))) return this;
+    if (this._storeOptionsAsProperties) {
+      this[key] = value;
+    } else {
+      this._optionValues[key] = value;
+    }
     this._optionValueSources[key] = source;
     return this;
   }
@@ -1584,7 +1602,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
       if (option.envVar && option.envVar in process.env) {
         const optionKey = option.attributeName();
         // Priority check. Do not overwrite cli or options from unknown source (client-code).
-        if (this.getOptionValue(optionKey) === undefined || ['default', 'config', 'env'].includes(this.getOptionValueSource(optionKey))) {
+        if (this.getOptionValue(optionKey) === undefined || this._isNewSourcePreferred('env', this.getOptionValueSource(optionKey))) {
           if (option.required || option.optional) { // option can take a value
             // keep very simple, optional always takes value
             this.emit(`optionEnv:${option.name()}`, process.env[option.envVar]);
@@ -1597,6 +1615,15 @@ Expecting one of '${allowedValues.join("', '")}'`);
     });
   }
 
+  /**
+   * Check if newSource is preferred.
+   *
+   * @api private
+   */
+  _isNewSourcePreferred(newSource, existingSource) {
+    return this._priorities.indexOf(newSource) <= this._priorities.indexOf(existingSource);
+  }
+
   /**
    * Apply any implied option values, if option is undefined or default value.
    *
@@ -1605,7 +1632,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
   _parseOptionsImplied() {
     const dualHelper = new DualOptions(this.options);
     const hasCustomOptionValue = (optionKey) => {
-      return this.getOptionValue(optionKey) !== undefined && !['default', 'implied'].includes(this.getOptionValueSource(optionKey));
+      return this.getOptionValue(optionKey) !== undefined && !this._isNewSourcePreferred('implied', this.getOptionValueSource(optionKey));
     };
     this.options
       .filter(option => (option.implied !== undefined) &&
diff --git a/typings/index.d.ts b/typings/index.d.ts
index 9f3d8dff8..aa65b5f69 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -266,7 +266,7 @@ export interface OutputConfiguration {
 
 export type AddHelpTextPosition = 'beforeAll' | 'before' | 'after' | 'afterAll';
 export type HookEvent = 'preSubcommand' | 'preAction' | 'postAction';
-export type OptionValueSource = 'default' | 'env' | 'config' | 'cli';
+export type OptionValueSource = 'default' | 'implied' | 'config' | 'env' | 'cli' | null;
 
 export interface OptionValues {
   [key: string]: any;
@@ -595,7 +595,7 @@ export class Command {
   /**
    * Retrieve option value source.
    */
-  getOptionValueSource(key: string): OptionValueSource;
+  getOptionValueSource(key: string): OptionValueSource | undefined;
 
   /**
    * Alter parsing of short flags with optional values.
diff --git a/typings/index.test-d.ts b/typings/index.test-d.ts
index 94c0b53d1..7b8af12ea 100644
--- a/typings/index.test-d.ts
+++ b/typings/index.test-d.ts
@@ -172,7 +172,7 @@ expectType<commander.Command>(program.setOptionValue('example', true));
 expectType<commander.Command>(program.setOptionValueWithSource('example', [], 'cli'));
 
 // getOptionValueSource
-expectType<commander.OptionValueSource>(program.getOptionValueSource('example'));
+expectType<commander.OptionValueSource | undefined>(program.getOptionValueSource('example'));
 
 // combineFlagAndOptionalValue
 expectType<commander.Command>(program.combineFlagAndOptionalValue());