diff --git a/include/swift/DependencyScan/DependencyScanImpl.h b/include/swift/DependencyScan/DependencyScanImpl.h
index 433f3962d21..13408e2c98b 100644
--- a/include/swift/DependencyScan/DependencyScanImpl.h
+++ b/include/swift/DependencyScan/DependencyScanImpl.h
@@ -65,6 +65,9 @@ struct swiftscan_dependency_info_s {
   /// The list of source import infos.
   swiftscan_import_info_set_t *imports;
 
+  /// The list of source optional import infos.
+  swiftscan_import_info_set_t *optional_imports;
+
   /// Specific details of a particular kind of module.
   swiftscan_module_details_t details;
 };
diff --git a/include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h b/include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h
index c61cb26cd81..e1a324ef1b5 100644
--- a/include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h
+++ b/include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h
@@ -41,7 +41,7 @@ using llvm::BCVBR;
 const unsigned char MODULE_DEPENDENCY_CACHE_FORMAT_SIGNATURE[] = {'I', 'M', 'D','C'};
 const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MAJOR = 10;
 /// Increment this on every change.
-const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MINOR = 3;
+const unsigned MODULE_DEPENDENCY_CACHE_FORMAT_VERSION_MINOR = 4;
 
 /// Various identifiers in this format will rely on having their strings mapped
 /// using this ID.
diff --git a/lib/DependencyScan/DependencyScanJSON.cpp b/lib/DependencyScan/DependencyScanJSON.cpp
index 5f435b80873..fd609e1d197 100644
--- a/lib/DependencyScan/DependencyScanJSON.cpp
+++ b/lib/DependencyScan/DependencyScanJSON.cpp
@@ -228,9 +228,13 @@ void writeLinkLibraries(llvm::raw_ostream &out,
 
 void writeImportInfos(llvm::raw_ostream &out,
                       const swiftscan_import_info_set_t *imports,
-                      unsigned indentLevel, bool trailingComma) {
+                      bool optional, unsigned indentLevel,
+                      bool trailingComma) {
   out.indent(indentLevel * 2);
-  out << "\"imports\": ";
+  if (optional)
+    out << "\"optionalImports\": ";
+  else
+    out << "\"imports\": ";
   out << "[\n";
 
   for (size_t i = 0; i < imports->count; ++i) {
@@ -441,7 +445,9 @@ void writeJSON(llvm::raw_ostream &out,
                         /*trailingComma=*/true);
       writeLinkLibraries(out, moduleInfo.link_libraries,
                          3, /*trailingComma=*/true);
-      writeImportInfos(out, moduleInfo.imports,
+      writeImportInfos(out, moduleInfo.imports, /*optional*/ false,
+                       3, /*trailingComma=*/true);
+      writeImportInfos(out, moduleInfo.optional_imports, /*optional*/ true,
                        3, /*trailingComma=*/true);
     }
     // Swift and Clang-specific details.
diff --git a/lib/DependencyScan/ScanDependencies.cpp b/lib/DependencyScan/ScanDependencies.cpp
index 07f22e8c2a6..e5e3d29add5 100644
--- a/lib/DependencyScan/ScanDependencies.cpp
+++ b/lib/DependencyScan/ScanDependencies.cpp
@@ -922,37 +922,44 @@ static swiftscan_dependency_graph_t generateFullDependencyGraph(
     }
     moduleInfo->link_libraries = linkLibrarySet;
 
-    // Create source import infos set for this module
-    auto imports = moduleDependencyInfo.getModuleImports();
-    swiftscan_import_info_set_t *importInfoSet =
-        new swiftscan_import_info_set_t;
-    importInfoSet->count = imports.size();
-    importInfoSet->imports = new swiftscan_import_info_t[importInfoSet->count];
-    for (size_t i = 0; i < imports.size(); ++i) {
-      const auto &ii = imports[i];
-      swiftscan_import_info_s *iInfo = new swiftscan_import_info_s;
-      iInfo->import_identifier = create_clone(ii.importIdentifier.c_str());
-      iInfo->access_level =
-          static_cast<swiftscan_access_level_t>(ii.accessLevel);
+    auto createImportSetInfo = [&](ArrayRef<ScannerImportStatementInfo> imports)
+        -> swiftscan_import_info_set_t * {
+      swiftscan_import_info_set_t *importInfoSet =
+          new swiftscan_import_info_set_t;
+      importInfoSet->count = imports.size();
+      importInfoSet->imports =
+          new swiftscan_import_info_t[importInfoSet->count];
+      for (size_t i = 0; i < imports.size(); ++i) {
+        const auto &ii = imports[i];
+        swiftscan_import_info_s *iInfo = new swiftscan_import_info_s;
+        iInfo->import_identifier = create_clone(ii.importIdentifier.c_str());
+        iInfo->access_level =
+            static_cast<swiftscan_access_level_t>(ii.accessLevel);
 
-      const auto &sourceLocations = ii.importLocations;
-      swiftscan_source_location_set_t *sourceLocSet =
-          new swiftscan_source_location_set_t;
-      sourceLocSet->count = sourceLocations.size();
-      sourceLocSet->source_locations =
-          new swiftscan_source_location_t[sourceLocSet->count];
-      for (size_t j = 0; j < sourceLocations.size(); ++j) {
-        const auto &sl = sourceLocations[j];
-        swiftscan_source_location_s *slInfo = new swiftscan_source_location_s;
-        slInfo->buffer_identifier = create_clone(sl.bufferIdentifier.c_str());
-        slInfo->line_number = sl.lineNumber;
-        slInfo->column_number = sl.columnNumber;
-        sourceLocSet->source_locations[j] = slInfo;
+        const auto &sourceLocations = ii.importLocations;
+        swiftscan_source_location_set_t *sourceLocSet =
+            new swiftscan_source_location_set_t;
+        sourceLocSet->count = sourceLocations.size();
+        sourceLocSet->source_locations =
+            new swiftscan_source_location_t[sourceLocSet->count];
+        for (size_t j = 0; j < sourceLocations.size(); ++j) {
+          const auto &sl = sourceLocations[j];
+          swiftscan_source_location_s *slInfo = new swiftscan_source_location_s;
+          slInfo->buffer_identifier = create_clone(sl.bufferIdentifier.c_str());
+          slInfo->line_number = sl.lineNumber;
+          slInfo->column_number = sl.columnNumber;
+          sourceLocSet->source_locations[j] = slInfo;
+        }
+        iInfo->source_locations = sourceLocSet;
+        importInfoSet->imports[i] = iInfo;
       }
-      iInfo->source_locations = sourceLocSet;
-      importInfoSet->imports[i] = iInfo;
-    }
-    moduleInfo->imports = importInfoSet;
+      return importInfoSet;
+    };
+    // Create source import infos set for this module
+    moduleInfo->imports =
+        createImportSetInfo(moduleDependencyInfo.getModuleImports());
+    moduleInfo->optional_imports =
+        createImportSetInfo(moduleDependencyInfo.getOptionalModuleImports());
   }
 
   swiftscan_dependency_graph_t result = new swiftscan_dependency_graph_s;
diff --git a/test/ScanDependencies/serialized_imports.swift b/test/ScanDependencies/serialized_imports.swift
index ae87a32eb11..41b3945a715 100644
--- a/test/ScanDependencies/serialized_imports.swift
+++ b/test/ScanDependencies/serialized_imports.swift
@@ -40,10 +40,16 @@
 // CHECK-IMPORTS-NEXT:          "importLocations": [
 // CHECK-IMPORTS-NEXT:            {
 // CHECK-IMPORTS-NEXT:              "bufferIdentifier": "{{.*}}serialized_imports.swift",
-// CHECK-IMPORTS-NEXT:              "linuNumber": 49,
+// CHECK-IMPORTS-NEXT:              "linuNumber": 54,
 // CHECK-IMPORTS-NEXT:              "columnNumber": 8
 // CHECK-IMPORTS-NEXT:            }
-// CHECK-IMPORTS-NEXT:          ]
+
+// CHECK-IMPORTS:          "optionalImports": [
+// CHECK-IMPORTS-NEXT:        {
+// CHECK-IMPORTS-NEXT:          "identifier": "E_Private",
+// CHECK-IMPORTS-NEXT:          "accessLevel": "public"
 // CHECK-IMPORTS-NEXT:        }
+// CHECK-IMPORTS-NEXT:      ],
 
 import E
+import E.Private