diff --git a/include/swift/AST/Module.h b/include/swift/AST/Module.h
index 6e624e197a130..34cdcb5237210 100644
--- a/include/swift/AST/Module.h
+++ b/include/swift/AST/Module.h
@@ -916,11 +916,9 @@ class ModuleDecl
   void lookupTopLevelDeclsByObjCName(SmallVectorImpl<Decl *> &Results,
                                      DeclName name);
 
-  /// This is a hack for 'main' file parsing and the integrated REPL.
-  ///
-  /// FIXME: Refactor main file parsing to not pump the parser incrementally.
-  /// FIXME: Remove the integrated REPL.
-  void clearLookupCache();
+  /// This is a hack for SynthesizedFileUnit and code completion. Do not add new
+  /// uses of it.
+  void clearLookupCache(bool includingImports = true);
 
   /// Finds all class members defined in this module.
   ///
diff --git a/lib/AST/Module.cpp b/lib/AST/Module.cpp
index 02144fbd1853a..8ea0939e31b19 100644
--- a/lib/AST/Module.cpp
+++ b/lib/AST/Module.cpp
@@ -3239,8 +3239,9 @@ bool SourceFile::shouldCrossImport() const {
          getASTContext().LangOpts.EnableCrossImportOverlays;
 }
 
-void ModuleDecl::clearLookupCache() {
-  getASTContext().getImportCache().clear();
+void ModuleDecl::clearLookupCache(bool includingImports) {
+  if (includingImports)
+    getASTContext().getImportCache().clear();
 
   setIsObjCNameLookupCachePopulated(false);
   ObjCNameLookupCache.clear();
@@ -3495,6 +3496,8 @@ void SourceFile::addTopLevelDecl(Decl *d) {
   auto &ctx = getASTContext();
   auto *mutableThis = const_cast<SourceFile *>(this);
   ctx.evaluator.clearCachedOutput(ParseTopLevelDeclsRequest{mutableThis});
+
+  getParentModule()->clearLookupCache(/*includingImports*/isa<ImportDecl>(d));
 }
 
 void SourceFile::prependTopLevelDecl(Decl *d) {
diff --git a/test/IDE/pr83369.swift b/test/IDE/pr83369.swift
new file mode 100644
index 0000000000000..6fcd79c8ed64c
--- /dev/null
+++ b/test/IDE/pr83369.swift
@@ -0,0 +1,9 @@
+// RUN: %batch-code-completion -module-name main
+
+extension Int {}
+
+// Make sure we can resolve P here.
+protocol P<X> where X: main.#^COMPLETE^# {
+  associatedtype X
+}
+// COMPLETE: Decl[Protocol]/CurrModule: P[#P#]; name=P