diff --git a/include/swift/Option/Options.td b/include/swift/Option/Options.td
index 14bfd9b3060f0..45590a085dd61 100644
--- a/include/swift/Option/Options.td
+++ b/include/swift/Option/Options.td
@@ -1670,6 +1670,15 @@ def omit_extension_block_symbols: Flag<["-"], "omit-extension-block-symbols">,
         NoInteractiveOption, SupplementaryOutput, HelpHidden]>,
   HelpText<"Directly associate members and conformances with the extended nominal when generating symbol graphs instead of emitting 'swift.extension' symbols for extensions to external types">;
 
+// swift-synthesize-interface-only options
+def include_submodules : Flag<["-"], "include-submodules">,
+  Flags<[NoDriverOption, SwiftSynthesizeInterfaceOption]>,
+  HelpText<"Also print the declarations synthesized for any Clang submodules">;
+
+def print_fully_qualified_types : Flag<["-"], "print-fully-qualified-types">,
+  Flags<[NoDriverOption, SwiftSynthesizeInterfaceOption]>,
+  HelpText<"Always print fully qualified type names">;
+
 // swift-symbolgraph-extract-only options
 def output_dir : Separate<["-"], "output-dir">,
   Flags<[NoDriverOption, SwiftSymbolGraphExtractOption, SwiftAPIDigesterOption,
diff --git a/lib/DriverTool/swift_synthesize_interface_main.cpp b/lib/DriverTool/swift_synthesize_interface_main.cpp
index fbb0f2e7348d4..85b2e7022dac7 100644
--- a/lib/DriverTool/swift_synthesize_interface_main.cpp
+++ b/lib/DriverTool/swift_synthesize_interface_main.cpp
@@ -200,11 +200,19 @@ int swift_synthesize_interface_main(ArrayRef<const char *> Args,
     return EXIT_FAILURE;
   }
 
-  StreamPrinter printer(fs);
   PrintOptions printOpts =
       PrintOptions::printModuleInterface(/*printFullConvention=*/true);
-  ide::printModuleInterface(M, /*GroupNames=*/{},
-                            /*TraversalOptions=*/std::nullopt, printer,
+  if (ParsedArgs.hasArg(OPT_print_fully_qualified_types)) {
+    printOpts.FullyQualifiedTypes = true;
+  }
+
+  swift::OptionSet<swift::ide::ModuleTraversal> traversalOpts = std::nullopt;
+  if (ParsedArgs.hasArg(OPT_include_submodules)) {
+    traversalOpts = swift::ide::ModuleTraversal::VisitSubmodules;
+  }
+
+  StreamPrinter printer(fs);
+  ide::printModuleInterface(M, /*GroupNames=*/{}, traversalOpts, printer,
                             printOpts, /*PrintSynthesizedExtensions=*/false);
 
   return EXIT_SUCCESS;
diff --git a/test/SynthesizeInterfaceTool/Inputs/ExplicitSubmodule.h b/test/SynthesizeInterfaceTool/Inputs/ExplicitSubmodule.h
new file mode 100644
index 0000000000000..a4163e1c640f2
--- /dev/null
+++ b/test/SynthesizeInterfaceTool/Inputs/ExplicitSubmodule.h
@@ -0,0 +1,3 @@
+struct ExplicitSubmoduleStruct {
+  int value;
+};
diff --git a/test/SynthesizeInterfaceTool/Inputs/ImplicitSubmodule.h b/test/SynthesizeInterfaceTool/Inputs/ImplicitSubmodule.h
new file mode 100644
index 0000000000000..0c7e087da9405
--- /dev/null
+++ b/test/SynthesizeInterfaceTool/Inputs/ImplicitSubmodule.h
@@ -0,0 +1,3 @@
+struct ImplicitSubmoduleStruct {
+  int value;
+};
diff --git a/test/SynthesizeInterfaceTool/Inputs/TopLevelModule.h b/test/SynthesizeInterfaceTool/Inputs/TopLevelModule.h
new file mode 100644
index 0000000000000..cd350cef96ac6
--- /dev/null
+++ b/test/SynthesizeInterfaceTool/Inputs/TopLevelModule.h
@@ -0,0 +1,3 @@
+struct TopLevelModuleStruct {
+  int value;
+};
diff --git a/test/SynthesizeInterfaceTool/Inputs/module.modulemap b/test/SynthesizeInterfaceTool/Inputs/module.modulemap
index 51fb805cd4e6f..d1eee6963b867 100644
--- a/test/SynthesizeInterfaceTool/Inputs/module.modulemap
+++ b/test/SynthesizeInterfaceTool/Inputs/module.modulemap
@@ -6,3 +6,15 @@ module mcxx {
   requires cplusplus
   header "mcxx.h"
 }
+
+module TopLevelModule {
+  header "TopLevelModule.h"
+
+  module ImplicitSubmodule {
+    header "ImplicitSubmodule.h"
+  }
+
+  explicit module ExplicitSubmodule {
+    header "ExplicitSubmodule.h"
+  }
+}
diff --git a/test/SynthesizeInterfaceTool/fully-qualified-types.swift b/test/SynthesizeInterfaceTool/fully-qualified-types.swift
new file mode 100644
index 0000000000000..5cb7165b1da50
--- /dev/null
+++ b/test/SynthesizeInterfaceTool/fully-qualified-types.swift
@@ -0,0 +1,10 @@
+// RUN: %target-swift-synthesize-interface -module-name m1 -print-fully-qualified-types -I %S/Inputs -o - | %FileCheck %s
+
+// CHECK:     public struct MyStruct {
+// CHECK-DAG:     public init()
+// CHECK-DAG:     public init(value: Swift.Int32)
+// CHECK-DAG:     public var value: Swift.Int32
+// CHECK-DAG: }
+// CHECK-DAG: extension m1.MyStruct {
+// CHECK-DAG:     public func printValue()
+// CHECK-DAG: }
diff --git a/test/SynthesizeInterfaceTool/include-submodules.swift b/test/SynthesizeInterfaceTool/include-submodules.swift
new file mode 100644
index 0000000000000..26b6407d28fdd
--- /dev/null
+++ b/test/SynthesizeInterfaceTool/include-submodules.swift
@@ -0,0 +1,39 @@
+// RUN: %target-swift-synthesize-interface -module-name TopLevelModule -I %S/Inputs -o - | %FileCheck %s
+// RUN: %target-swift-synthesize-interface -module-name TopLevelModule -include-submodules -I %S/Inputs -o - | %FileCheck %s --check-prefix=IMPLICIT
+// RUN: %target-swift-synthesize-interface -module-name TopLevelModule.ExplicitSubmodule -I %S/Inputs -o - | %FileCheck %s --check-prefix=EXPLICIT
+
+// CHECK:     import TopLevelModule.ExplicitSubmodule
+// CHECK-DAG: import TopLevelModule.ImplicitSubmodule
+// CHECK-DAG: public struct TopLevelModuleStruct {
+// CHECK-DAG:     public init()
+// CHECK-DAG:     public init(value: Int32)
+// CHECK-DAG:     public var value: Int32
+// CHECK-DAG: }
+
+// CHECK-NOT: ImplicitModuleStruct
+// CHECK-NOT: ExplicitModuleStruct
+
+// IMPLICIT:     import TopLevelModule.ExplicitSubmodule
+// IMPLICIT-DAG: import TopLevelModule.ImplicitSubmodule
+// IMPLICIT-DAG: public struct TopLevelModuleStruct {
+// IMPLICIT-DAG:     public init()
+// IMPLICIT-DAG:     public init(value: Int32)
+// IMPLICIT-DAG:     public var value: Int32
+// IMPLICIT-DAG: }
+// IMPLICIT-DAG: public struct ImplicitSubmoduleStruct {
+// IMPLICIT-DAG:     public init()
+// IMPLICIT-DAG:     public init(value: Int32)
+// IMPLICIT-DAG:     public var value: Int32
+// IMPLICIT-DAG: }
+
+// IMPLICIT-NOT: ExplicitSubmoduleStruct
+
+// EXPLICIT:     public struct ExplicitSubmoduleStruct {
+// EXPLICIT-DAG:     public init()
+// EXPLICIT-DAG:     public init(value: Int32)
+// EXPLICIT-DAG:     public var value: Int32
+// EXPLICIT-DAG: }
+
+// EXPLICIT-NOT: import TopLevelModule{{.*}}
+// EXPLICIT-NOT: TopLevelModuleStruct
+// EXPLICIT-NOT: ImplicitModuleStruct