diff --git a/Sources/SwiftCompilerPlugin/CompilerPlugin.swift b/Sources/SwiftCompilerPlugin/CompilerPlugin.swift
index 23a2b22cdb2..2e8c2edbd76 100644
--- a/Sources/SwiftCompilerPlugin/CompilerPlugin.swift
+++ b/Sources/SwiftCompilerPlugin/CompilerPlugin.swift
@@ -12,12 +12,22 @@
 // NOTE: This basic plugin mechanism is mostly copied from
 // https://github.com/apple/swift-package-manager/blob/main/Sources/PackagePlugin/Plugin.swift
 
-@_implementationOnly import Foundation
-@_implementationOnly import SwiftCompilerPluginMessageHandling
 import SwiftSyntaxMacros
 
+#if swift(>=5.11)
+private import Foundation
+private import SwiftCompilerPluginMessageHandling
+#else
+import Foundation
+import SwiftCompilerPluginMessageHandling
+#endif
+
 #if os(Windows)
-@_implementationOnly import ucrt
+#if swift(>=5.11)
+private import ucrt
+#else
+import ucrt
+#endif
 #endif
 
 //
@@ -169,8 +179,8 @@ extension CompilerPlugin {
 }
 
 internal struct PluginHostConnection: MessageConnection {
-  let inputStream: FileHandle
-  let outputStream: FileHandle
+  fileprivate let inputStream: FileHandle
+  fileprivate let outputStream: FileHandle
 
   func sendMessage<TX: Encodable>(_ message: TX) throws {
     // Encode the message as JSON.
diff --git a/Sources/SwiftSyntax/SyntaxText.swift b/Sources/SwiftSyntax/SyntaxText.swift
index 310bcb22836..59aa52c4f68 100644
--- a/Sources/SwiftSyntax/SyntaxText.swift
+++ b/Sources/SwiftSyntax/SyntaxText.swift
@@ -10,12 +10,22 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if swift(>=5.11)
 #if canImport(Darwin)
-@_implementationOnly import Darwin
+private import Darwin
 #elseif canImport(Glibc)
-@_implementationOnly import Glibc
+private import Glibc
 #elseif canImport(Musl)
-@_implementationOnly import Musl
+private import Musl
+#endif
+#else
+#if canImport(Darwin)
+import Darwin
+#elseif canImport(Glibc)
+import Glibc
+#elseif canImport(Musl)
+import Musl
+#endif
 #endif
 
 /// Represent a string.
diff --git a/Tests/SwiftParserTest/LinkageTests.swift b/Tests/SwiftParserTest/LinkageTests.swift
index 8c9f736fb15..f5f663e3200 100644
--- a/Tests/SwiftParserTest/LinkageTests.swift
+++ b/Tests/SwiftParserTest/LinkageTests.swift
@@ -53,6 +53,7 @@ final class LinkageTest: ParserTestCase {
         .library("-lswiftCompatibilityConcurrency"),
         .library("-lswiftCompatibilityPacks", condition: .mayBeAbsent("Only in newer compilers")),
         .library("-lswiftCore"),
+        .library("-lswiftDarwin"),
         .library("-lswiftSwiftOnoneSupport", condition: .when(configuration: .debug)),
         .library("-lswift_Concurrency"),
         .library("-lswift_StringProcessing", condition: .mayBeAbsent("Starting in Xcode 14 this library is not always autolinked")),
@@ -70,7 +71,7 @@ final class LinkageTest: ParserTestCase {
         .library("-lswiftCompatibilityPacks", condition: .mayBeAbsent("Only in newer compilers")),
         .library("-lswiftCore"),
         .library("-lswiftCoreFoundation", condition: .when(compilationCondition: .osLogDependency)),
-        .library("-lswiftDarwin", condition: .when(compilationCondition: .osLogDependency)),
+        .library("-lswiftDarwin"),
         .library("-lswiftDispatch", condition: .when(compilationCondition: .osLogDependency)),
         .library("-lswiftFoundation", condition: .when(compilationCondition: .osLogDependency)),
         .library("-lswiftIOKit", condition: .when(compilationCondition: .osLogDependency)),