diff --git a/Sources/Arguments.swift b/Sources/Arguments.swift
index cf69c72a..7025c689 100644
--- a/Sources/Arguments.swift
+++ b/Sources/Arguments.swift
@@ -324,13 +324,15 @@ func parseCommaDelimitedList(_ string: String) -> [String] {
 /// Parse a comma-delimited string into an array of rules
 let allRules = Set(FormatRules.all.map(\.name))
 let defaultRules = Set(FormatRules.default.map(\.name))
-func parseRules(_ rules: String) throws -> [String] {
+func parseRules(_ rules: String, ignoreUnknown: Bool) throws -> [String] {
     try parseCommaDelimitedList(rules).flatMap { proposedName -> [String] in
         let lowercaseName = proposedName.lowercased()
         if let name = allRules.first(where: { $0.lowercased() == lowercaseName }) {
             return [name]
         } else if lowercaseName == "all" {
             return FormatRules.all.compactMap { $0.isDeprecated ? nil : $0.name }
+        } else if ignoreUnknown {
+            return []
         }
         if Descriptors.all.contains(where: { $0.argumentName == lowercaseName }) {
             for rule in FormatRules.all where rule.options.contains(lowercaseName) {
@@ -348,6 +350,18 @@ func parseRules(_ rules: String) throws -> [String] {
     }
 }
 
+func curryParseRules(config: [String: String]) -> (String) throws -> [String] {
+    {
+        try parseRules($0, ignoreUnknown: config["unknown-rules"].map {
+            switch $0 {
+            case "ignore": return true
+            case "error": return false
+            default: throw FormatError.options("Unknown value '\($0)' for --unknown-rules option")
+            }
+        } ?? false)
+    }
+}
+
 /// Parse single file path, disallowing globs or commas
 func parsePath(_ path: String, for argument: String, in directory: String) throws -> URL {
     let expandedPath = expandPath(path, in: directory)
@@ -369,6 +383,7 @@ func parsePaths(_ paths: String, in directory: String) throws -> [URL] {
 
 /// Merge two dictionaries of arguments
 func mergeArguments(_ args: [String: String], into config: [String: String]) throws -> [String: String] {
+    let parseRules = curryParseRules(config: config)
     var input = config
     var output = args
     // Merge excluded urls
@@ -661,6 +676,7 @@ private func processOption(_ key: String,
 
 /// Parse rule names from arguments
 public func rulesFor(_ args: [String: String], lint: Bool, initial: Set<String>? = nil) throws -> Set<String> {
+    let parseRules = curryParseRules(config: args)
     var rules = initial ?? allRules
 
     if let specifiedRules = try args["rules"].map({ try Set(parseRules($0)) }) {
@@ -779,6 +795,7 @@ func warningsForArguments(_ args: [String: String], ignoreUnusedOptions: Bool =
             warnings.append("--\(option.argumentName) option is deprecated. \(message)")
         }
     }
+    let parseRules = curryParseRules(config: args)
     for name in Set(rulesArguments.flatMap { (try? args[$0].map(parseRules) ?? []) ?? [] }) {
         if let message = FormatRules.byName[name]?.deprecationMessage {
             warnings.append("\(name) rule is deprecated. \(message)")
@@ -837,6 +854,7 @@ let commandLineArguments = [
     "strict",
     "verbose",
     "quiet",
+    "unknown-rules",
     "reporter",
     "report",
     // Misc
diff --git a/Sources/CommandLine.swift b/Sources/CommandLine.swift
index f63092ec..d53fc8cd 100644
--- a/Sources/CommandLine.swift
+++ b/Sources/CommandLine.swift
@@ -208,6 +208,7 @@ func printHelp(as type: CLI.OutputType) {
     --conflict-markers \(stripMarkdown(Descriptors.ignoreConflictMarkers.help))
     --swift-version    \(stripMarkdown(Descriptors.swiftVersion.help))
     --language-mode    \(stripMarkdown(Descriptors.languageMode.help))
+    --unknown-rules    How unknown rules are handled: "error" (default) or "ignore"
     --min-version      The minimum SwiftFormat version to be used for these files
     --cache            Path to cache file, or "clear" or "ignore" the default cache
     --dry-run          Run in "dry" mode (without actually changing any files)
@@ -492,7 +493,7 @@ func processArguments(_ args: [String], environment: [String: String] = [:], in
         }
 
         // Show rule info
-        if let names = try args["rule-info"].map(parseRules) {
+        if let names = try args["rule-info"].map({ try parseRules($0, ignoreUnknown: false) }) {
             let names = names.isEmpty ? allRules.sorted() : names.sorted()
             for name in names {
                 try printRuleInfo(for: name, as: .content)
diff --git a/Tests/ArgumentsTests.swift b/Tests/ArgumentsTests.swift
index ee57dd7a..54e48d81 100644
--- a/Tests/ArgumentsTests.swift
+++ b/Tests/ArgumentsTests.swift
@@ -660,7 +660,7 @@ class ArgumentsTests: XCTestCase {
         let args = ["rules": "braces,fileHeader"]
         let config = ["rules": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let rules = try parseRules(result["rules"]!)
+        let rules = try parseRules(result["rules"]!, ignoreUnknown: false)
         XCTAssertEqual(rules, ["braces", "fileHeader"])
     }
 
@@ -668,7 +668,7 @@ class ArgumentsTests: XCTestCase {
         let args = ["rules": ""]
         let config = ["rules": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let rules = try parseRules(result["rules"]!)
+        let rules = try parseRules(result["rules"]!, ignoreUnknown: false)
         XCTAssertEqual(Set(rules), Set(["braces", "consecutiveSpaces"]))
     }
 
@@ -676,7 +676,7 @@ class ArgumentsTests: XCTestCase {
         let args = ["enable": "braces,fileHeader"]
         let config = ["enable": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let enabled = try parseRules(result["enable"]!)
+        let enabled = try parseRules(result["enable"]!, ignoreUnknown: false)
         XCTAssertEqual(enabled, ["braces", "consecutiveSpaces", "fileHeader"])
     }
 
@@ -684,7 +684,7 @@ class ArgumentsTests: XCTestCase {
         let args = ["disable": "braces,fileHeader"]
         let config = ["disable": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let disabled = try parseRules(result["disable"]!)
+        let disabled = try parseRules(result["disable"]!, ignoreUnknown: false)
         XCTAssertEqual(disabled, ["braces", "consecutiveSpaces", "fileHeader"])
     }
 
@@ -692,7 +692,7 @@ class ArgumentsTests: XCTestCase {
         let args = ["rules": "braces,fileHeader"]
         let config = ["rules": "consecutiveSpaces", "disable": "braces", "enable": "redundantSelf"]
         let result = try mergeArguments(args, into: config)
-        let disabled = try parseRules(result["rules"]!)
+        let disabled = try parseRules(result["rules"]!, ignoreUnknown: false)
         XCTAssertEqual(disabled, ["braces", "fileHeader"])
         XCTAssertNil(result["enabled"])
         XCTAssertNil(result["disabled"])
@@ -702,11 +702,11 @@ class ArgumentsTests: XCTestCase {
         let args = ["enable": "braces"]
         let config = ["rules": "fileHeader", "disable": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let rules = try parseRules(result["rules"]!)
+        let rules = try parseRules(result["rules"]!, ignoreUnknown: false)
         XCTAssertEqual(rules, ["fileHeader"])
-        let enabled = try parseRules(result["enable"]!)
+        let enabled = try parseRules(result["enable"]!, ignoreUnknown: false)
         XCTAssertEqual(enabled, ["braces"])
-        let disabled = try parseRules(result["disable"]!)
+        let disabled = try parseRules(result["disable"]!, ignoreUnknown: false)
         XCTAssertEqual(disabled, ["consecutiveSpaces"])
     }
 
@@ -714,11 +714,11 @@ class ArgumentsTests: XCTestCase {
         let args = ["disable": "braces"]
         let config = ["rules": "braces,fileHeader", "enable": "consecutiveSpaces,braces"]
         let result = try mergeArguments(args, into: config)
-        let rules = try parseRules(result["rules"]!)
+        let rules = try parseRules(result["rules"]!, ignoreUnknown: false)
         XCTAssertEqual(rules, ["fileHeader"])
-        let enabled = try parseRules(result["enable"]!)
+        let enabled = try parseRules(result["enable"]!, ignoreUnknown: false)
         XCTAssertEqual(enabled, ["consecutiveSpaces"])
-        let disabled = try parseRules(result["disable"]!)
+        let disabled = try parseRules(result["disable"]!, ignoreUnknown: false)
         XCTAssertEqual(disabled, ["braces"])
     }
 
@@ -850,29 +850,39 @@ class ArgumentsTests: XCTestCase {
     // MARK: parse rules
 
     func testParseRulesCaseInsensitive() throws {
-        let rules = try parseRules("strongoutlets")
+        let rules = try parseRules("strongoutlets", ignoreUnknown: false)
         XCTAssertEqual(rules, ["strongOutlets"])
     }
 
     func testParseAllRule() throws {
-        let rules = try parseRules("all")
+        let rules = try parseRules("all", ignoreUnknown: false)
         XCTAssertEqual(rules, FormatRules.all.compactMap {
             $0.isDeprecated ? nil : $0.name
         })
     }
 
     func testParseInvalidRuleThrows() {
-        XCTAssertThrowsError(try parseRules("strongOutlet")) { error in
+        XCTAssertThrowsError(try parseRules("strongOutlet", ignoreUnknown: false)) { error in
             XCTAssertEqual("\(error)", "Unknown rule 'strongOutlet'. Did you mean 'strongOutlets'?")
         }
     }
 
     func testParseOptionAsRuleThrows() {
-        XCTAssertThrowsError(try parseRules("import-grouping")) { error in
+        XCTAssertThrowsError(try parseRules("import-grouping", ignoreUnknown: false)) { error in
             XCTAssert("\(error)".contains("'sortImports'"))
         }
     }
 
+    func testSuppressInvalidRuleError() throws {
+        let rules = try parseRules("strongOutlet,isEmpty", ignoreUnknown: true)
+        XCTAssertEqual(rules, ["isEmpty"])
+    }
+
+    func testSuppressOptionAsRuleError() throws {
+        let rules = try parseRules("import-grouping,isEmpty", ignoreUnknown: true)
+        XCTAssertEqual(rules, ["isEmpty"])
+    }
+
     // MARK: lintonly
 
     func testLintonlyRulesContain() throws {