diff --git a/Sources/Foundation/CMakeLists.txt b/Sources/Foundation/CMakeLists.txt
index 470364a0a2..b591310cda 100644
--- a/Sources/Foundation/CMakeLists.txt
+++ b/Sources/Foundation/CMakeLists.txt
@@ -21,7 +21,6 @@ add_library(Foundation
     ByteCountFormatter.swift
     CGFloat.swift
     CharacterSet.swift
-    Codable.swift
     DateComponents.swift
     DateComponentsFormatter.swift
     DateFormatter.swift
diff --git a/Sources/Foundation/Codable.swift b/Sources/Foundation/Codable.swift
deleted file mode 100644
index 4976f52655..0000000000
--- a/Sources/Foundation/Codable.swift
+++ /dev/null
@@ -1,59 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// This source file is part of the Swift.org open source project
-//
-// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
-// Licensed under Apache License v2.0 with Runtime Library Exception
-//
-// See https://swift.org/LICENSE.txt for license information
-// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
-//
-//===----------------------------------------------------------------------===//
-
-//===----------------------------------------------------------------------===//
-// Errors
-//===----------------------------------------------------------------------===//
-
-// Both of these error types bridge to NSError, and through the entry points they use, no further work is needed to make them localized.
-extension EncodingError : LocalizedError {}
-extension DecodingError : LocalizedError {}
-
-//===----------------------------------------------------------------------===//
-// Error Utilities
-//===----------------------------------------------------------------------===//
-
-extension DecodingError {
-    /// Returns a `.typeMismatch` error describing the expected type.
-    ///
-    /// - parameter path: The path of `CodingKey`s taken to decode a value of this type.
-    /// - parameter expectation: The type expected to be encountered.
-    /// - parameter reality: The value that was encountered instead of the expected type.
-    /// - returns: A `DecodingError` with the appropriate path and debug description.
-    internal static func _typeMismatch(at path: [CodingKey], expectation: Any.Type, reality: Any) -> DecodingError {
-        let description = "Expected to decode \(expectation) but found \(_typeDescription(of: reality)) instead."
-        return .typeMismatch(expectation, Context(codingPath: path, debugDescription: description))
-    }
-
-    /// Returns a description of the type of `value` appropriate for an error message.
-    ///
-    /// - parameter value: The value whose type to describe.
-    /// - returns: A string describing `value`.
-    /// - precondition: `value` is one of the types below.
-    fileprivate static func _typeDescription(of value: Any) -> String {
-        switch value {
-        case is NSNull:
-            return "a null value"
-        case is NSNumber: /* FIXME: If swift-corelibs-foundation isn't updated to use NSNumber, this check will be necessary: || value is Int || value is Double */
-            return "a number"
-        case is String:
-            return "a string/data"
-        case is [Any]:
-            return "an array"
-        case is [String : Any]:
-            return "a dictionary"
-        default:
-            return "\(type(of: value))"
-        }
-    }
-}
-