diff --git a/swift/internal/actions.bzl b/swift/internal/actions.bzl
index 931d22f51..fd7773877 100644
--- a/swift/internal/actions.bzl
+++ b/swift/internal/actions.bzl
@@ -37,6 +37,10 @@ swift_action_names = struct(
     # Precompiles an explicit module for a C/Objective-C module map and its
     # headers, emitting a `.pcm` file.
     PRECOMPILE_C_MODULE = "SwiftPrecompileCModule",
+
+    # Produces files that are usually fallout of the compilation such as
+    # .swiftmodule, -Swift.h and more.
+    DERIVE_FILES = "SwiftDeriveFiles",
 )
 
 def _apply_configurator(configurator, prerequisites, args):
diff --git a/swift/internal/compiling.bzl b/swift/internal/compiling.bzl
index a752d4147..778a6ae04 100644
--- a/swift/internal/compiling.bzl
+++ b/swift/internal/compiling.bzl
@@ -39,6 +39,7 @@ load(
     "SWIFT_FEATURE_EMIT_SWIFTINTERFACE",
     "SWIFT_FEATURE_ENABLE_BATCH_MODE",
     "SWIFT_FEATURE_ENABLE_LIBRARY_EVOLUTION",
+    "SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES",
     "SWIFT_FEATURE_ENABLE_TESTING",
     "SWIFT_FEATURE_FASTBUILD",
     "SWIFT_FEATURE_FULL_DEBUG_INFO",
@@ -52,6 +53,7 @@ load(
     "SWIFT_FEATURE_OPT",
     "SWIFT_FEATURE_OPT_USES_OSIZE",
     "SWIFT_FEATURE_OPT_USES_WMO",
+    "SWIFT_FEATURE_SPLIT_DERIVED_FILES_GENERATION",
     "SWIFT_FEATURE_STRICT_MODULES",
     "SWIFT_FEATURE_SUPPORTS_LIBRARY_EVOLUTION",
     "SWIFT_FEATURE_SYSTEM_MODULE",
@@ -106,6 +108,10 @@ def compile_action_configs():
             actions = [swift_action_names.COMPILE],
             configurators = [_output_object_or_file_map_configurator],
         ),
+        swift_toolchain_config.action_config(
+            actions = [swift_action_names.DERIVE_FILES],
+            configurators = [_output_swiftmodule_or_file_map_configurator],
+        ),
 
         # Emit precompiled Clang modules, and embed all files that were read
         # during compilation into the PCM.
@@ -131,11 +137,19 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [swift_action_names.COMPILE],
             configurators = [_emit_module_path_configurator],
+            not_features = [SWIFT_FEATURE_SPLIT_DERIVED_FILES_GENERATION],
+        ),
+        swift_toolchain_config.action_config(
+            actions = [swift_action_names.DERIVE_FILES],
+            configurators = [_emit_module_path_configurator],
         ),
 
         # Configure library evolution and the path to the .swiftinterface file.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-enable-library-evolution"),
             ],
@@ -145,23 +159,39 @@ def compile_action_configs():
             ],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_emit_module_interface_path_configurator],
             features = [
                 SWIFT_FEATURE_SUPPORTS_LIBRARY_EVOLUTION,
                 SWIFT_FEATURE_EMIT_SWIFTINTERFACE,
             ],
         ),
+
+        # Configure the path to the emitted *-Swift.h file.
         swift_toolchain_config.action_config(
             actions = [swift_action_names.COMPILE],
             configurators = [_emit_objc_header_path_configurator],
+            not_features = [
+                [SWIFT_FEATURE_NO_GENERATED_HEADER],
+                [SWIFT_FEATURE_SPLIT_DERIVED_FILES_GENERATION],
+            ],
+        ),
+        swift_toolchain_config.action_config(
+            actions = [swift_action_names.DERIVE_FILES],
+            configurators = [_emit_objc_header_path_configurator],
             not_features = [SWIFT_FEATURE_NO_GENERATED_HEADER],
         ),
 
         # Configure the location where compiler performance statistics are
         # dumped.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_stats_output_dir_configurator],
             features = [SWIFT_FEATURE_COMPILE_STATS],
         ),
@@ -177,14 +207,20 @@ def compile_action_configs():
         # Define appropriate conditional compilation symbols depending on the
         # build mode.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-DDEBUG"),
             ],
             features = [[SWIFT_FEATURE_DBG], [SWIFT_FEATURE_FASTBUILD]],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-DNDEBUG"),
             ],
@@ -195,14 +231,20 @@ def compile_action_configs():
         # `-O` unless the `swift.opt_uses_osize` feature is enabled, then use
         # `-Osize`.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-Onone"),
             ],
             features = [[SWIFT_FEATURE_DBG], [SWIFT_FEATURE_FASTBUILD]],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-O"),
             ],
@@ -210,7 +252,10 @@ def compile_action_configs():
             not_features = [SWIFT_FEATURE_OPT_USES_OSIZE],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-Osize"),
             ],
@@ -220,7 +265,10 @@ def compile_action_configs():
         # If the `swift.opt_uses_wmo` feature is enabled, opt builds should also
         # automatically imply whole-module optimization.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-whole-module-optimization"),
             ],
@@ -230,7 +278,10 @@ def compile_action_configs():
         # Enable or disable serialization of debugging options into
         # swiftmodules.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg(
                     "-Xfrontend",
@@ -240,7 +291,10 @@ def compile_action_configs():
             features = [SWIFT_FEATURE_CACHEABLE_SWIFTMODULES],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg(
                     "-Xfrontend",
@@ -255,7 +309,10 @@ def compile_action_configs():
 
         # Enable testability if requested.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-enable-testing"),
             ],
@@ -267,12 +324,18 @@ def compile_action_configs():
         # `dsymutil` produces spurious warnings about symbols in the debug map
         # when run on DI emitted by `-gline-tables-only`.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [swift_toolchain_config.add_arg("-g")],
             features = [[SWIFT_FEATURE_DBG], [SWIFT_FEATURE_FULL_DEBUG_INFO]],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-gline-tables-only"),
             ],
@@ -282,7 +345,10 @@ def compile_action_configs():
 
         # Make paths written into debug info workspace-relative.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg(
                     "-Xwrapped-swift=-debug-prefix-pwd-is-dot",
@@ -297,7 +363,10 @@ def compile_action_configs():
 
         # Make paths written into coverage info workspace-relative.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg(
                     "-Xwrapped-swift=-coverage-prefix-pwd-is-dot",
@@ -316,7 +385,10 @@ def compile_action_configs():
     # supporting them either.
     action_configs += [
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-profile-generate"),
                 swift_toolchain_config.add_arg("-profile-coverage-mapping"),
@@ -324,14 +396,20 @@ def compile_action_configs():
             features = [SWIFT_FEATURE_COVERAGE],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-sanitize=address"),
             ],
             features = ["asan"],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg("-sanitize=thread"),
             ],
@@ -346,6 +424,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -361,7 +440,10 @@ def compile_action_configs():
         # Configure how implicit modules are handled--either using the module
         # cache, or disabled completely when using explicit modules.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_global_module_cache_configurator],
             features = [
                 SWIFT_FEATURE_IMPLICIT_MODULES,
@@ -369,7 +451,10 @@ def compile_action_configs():
             ],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 swift_toolchain_config.add_arg(
                     "-Xwrapped-swift=-ephemeral-module-cache",
@@ -381,6 +466,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -449,12 +535,18 @@ def compile_action_configs():
     #### Search paths for Swift module dependencies
     action_configs.extend([
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_dependencies_swiftmodules_configurator],
             not_features = [SWIFT_FEATURE_VFSOVERLAY],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 _dependencies_swiftmodules_vfsoverlay_configurator,
             ],
@@ -467,6 +559,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [_framework_search_paths_configurator],
@@ -479,6 +572,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -492,6 +586,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [_dependencies_clang_modules_configurator],
@@ -500,6 +595,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [_dependencies_clang_modulemaps_configurator],
@@ -514,6 +610,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -532,7 +629,10 @@ def compile_action_configs():
         # flags themselves, since some Swift users enable it there as a build
         # performance hack.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_batch_mode_configurator],
             features = [SWIFT_FEATURE_ENABLE_BATCH_MODE],
             not_features = [SWIFT_FEATURE_OPT, SWIFT_FEATURE_OPT_USES_WMO],
@@ -540,7 +640,10 @@ def compile_action_configs():
 
         # Set the number of threads to use for WMO.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 partial.make(
                     _wmo_thread_count_configurator,
@@ -552,7 +655,10 @@ def compile_action_configs():
             features = [SWIFT_FEATURE_OPT, SWIFT_FEATURE_OPT_USES_WMO],
         ),
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [
                 partial.make(
                     _wmo_thread_count_configurator,
@@ -568,14 +674,29 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [_module_name_configurator],
         ),
 
+        # Pass extra flags for swiftmodule only compilations
+        swift_toolchain_config.action_config(
+            actions = [swift_action_names.DERIVE_FILES],
+            configurators = [
+                swift_toolchain_config.add_arg(
+                    "-experimental-skip-non-inlinable-function-bodies",
+                ),
+            ],
+            features = [SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES],
+        ),
+
         # Configure index-while-building.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_index_while_building_configurator],
             features = [SWIFT_FEATURE_INDEX_WHILE_BUILDING],
         ),
@@ -583,13 +704,19 @@ def compile_action_configs():
         # User-defined conditional compilation flags (defined for Swift; those
         # passed directly to ClangImporter are handled above).
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_conditional_compilation_flag_configurator],
         ),
 
         # Disable auto-linking for prebuilt static frameworks.
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_static_frameworks_disable_autolink_configurator],
         ),
     ]
@@ -600,7 +727,10 @@ def compile_action_configs():
     # the rule implementations as a last resort.
     action_configs.append(
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_user_compile_flags_configurator],
         ),
     )
@@ -609,6 +739,7 @@ def compile_action_configs():
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [_source_files_configurator],
@@ -618,33 +749,50 @@ def compile_action_configs():
     # Add additional input files to the sandbox (does not modify flags).
     action_configs.append(
         swift_toolchain_config.action_config(
-            actions = [swift_action_names.COMPILE],
+            actions = [
+                swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
+            ],
             configurators = [_additional_inputs_configurator],
         ),
     )
 
     return action_configs
 
-def _output_object_or_file_map_configurator(prerequisites, args):
-    """Adds the output file map or single object file to the command line."""
-    output_file_map = prerequisites.output_file_map
+def _output_or_file_map(output_file_map, outputs, args):
+    """Adds the output file map or single file to the command line."""
     if output_file_map:
         args.add("-output-file-map", output_file_map)
         return swift_toolchain_config.config_result(
             inputs = [output_file_map],
         )
 
-    object_files = prerequisites.object_files
-    if len(object_files) != 1:
+    if len(outputs) != 1:
         fail(
             "Internal error: If not using an output file map, there should " +
             "only be a single object file expected as the output, but we " +
-            "found: {}".format(object_files),
+            "found: {}".format(outputs),
         )
 
-    args.add("-o", object_files[0])
+    args.add("-o", outputs[0])
     return None
 
+def _output_object_or_file_map_configurator(prerequisites, args):
+    """Adds the output file map or single object file to the command line."""
+    return _output_or_file_map(
+        output_file_map = prerequisites.output_file_map,
+        outputs = prerequisites.object_files,
+        args = args,
+    )
+
+def _output_swiftmodule_or_file_map_configurator(prerequisites, args):
+    """Adds the output file map or single object file to the command line."""
+    return _output_or_file_map(
+        output_file_map = prerequisites.output_file_map,
+        outputs = [prerequisites.swiftmodule_file],
+        args = args,
+    )
+
 def _output_pcm_file_configurator(prerequisites, args):
     """Adds the `.pcm` output path to the command line."""
     args.add("-o", prerequisites.pcm_file)
@@ -1175,18 +1323,41 @@ def compile(
         target_name = target_name,
         user_compile_flags = copts + swift_toolchain.command_line_copts,
     )
-    all_compile_outputs = compact([
-        # The `.swiftmodule` file is explicitly listed as the first output
-        # because it will always exist and because Bazel uses it as a key for
-        # various things (such as the filename prefix for param files generated
-        # for that action). This guarantees some predictability.
-        compile_outputs.swiftmodule_file,
-        compile_outputs.swiftdoc_file,
-        compile_outputs.swiftinterface_file,
-        compile_outputs.generated_header_file,
-        compile_outputs.indexstore_directory,
-        compile_outputs.stats_directory,
-    ]) + compile_outputs.object_files + other_outputs
+
+    split_derived_file_generation = is_feature_enabled(
+        feature_configuration = feature_configuration,
+        feature_name = SWIFT_FEATURE_SPLIT_DERIVED_FILES_GENERATION,
+    )
+
+    if split_derived_file_generation:
+        all_compile_outputs = compact([
+            compile_outputs.swiftinterface_file,
+            compile_outputs.indexstore_directory,
+            compile_outputs.stats_directory,
+        ]) + compile_outputs.object_files
+        all_derived_outputs = compact([
+            # The `.swiftmodule` file is explicitly listed as the first output
+            # because it will always exist and because Bazel uses it as a key for
+            # various things (such as the filename prefix for param files generated
+            # for that action). This guarantees some predictability.
+            compile_outputs.swiftmodule_file,
+            compile_outputs.swiftdoc_file,
+            compile_outputs.generated_header_file,
+        ]) + other_outputs
+    else:
+        all_compile_outputs = compact([
+            # The `.swiftmodule` file is explicitly listed as the first output
+            # because it will always exist and because Bazel uses it as a key for
+            # various things (such as the filename prefix for param files generated
+            # for that action). This guarantees some predictability.
+            compile_outputs.swiftmodule_file,
+            compile_outputs.swiftdoc_file,
+            compile_outputs.swiftinterface_file,
+            compile_outputs.generated_header_file,
+            compile_outputs.indexstore_directory,
+            compile_outputs.stats_directory,
+        ]) + compile_outputs.object_files + other_outputs
+        all_derived_outputs = []
 
     # Merge the providers from our dependencies so that we have one each for
     # `SwiftInfo`, `CcInfo`, and `apple_common.Objc`. Then we can pass these
@@ -1260,6 +1431,19 @@ def compile(
         **struct_fields(compile_outputs)
     )
 
+    if split_derived_file_generation:
+        run_toolchain_action(
+            actions = actions,
+            action_name = swift_action_names.DERIVE_FILES,
+            feature_configuration = feature_configuration,
+            outputs = all_derived_outputs,
+            prerequisites = prerequisites,
+            progress_message = (
+                "Generating derived files for Swift module {}".format(module_name)
+            ),
+            swift_toolchain = swift_toolchain,
+        )
+
     run_toolchain_action(
         actions = actions,
         action_name = swift_action_names.COMPILE,
diff --git a/swift/internal/feature_names.bzl b/swift/internal/feature_names.bzl
index ad3ed8969..21257554a 100644
--- a/swift/internal/feature_names.bzl
+++ b/swift/internal/feature_names.bzl
@@ -227,3 +227,12 @@ SWIFT_FEATURE_NO_EMBED_DEBUG_MODULE = "swift.no_embed_debug_module"
 # files where the protoc command line might not be crafted correctly, so it
 # remains opt in.
 SWIFT_FEATURE_GENERATE_FROM_RAW_PROTO_FILES = "swift.generate_from_raw_proto_files"
+
+# If enabled and whole module optimisation is being used, the `*.swiftdoc`,
+# `*.swiftmodule` and `*-Swift.h` are generated with a separate action
+# rather than as part of the compilation.
+SWIFT_FEATURE_SPLIT_DERIVED_FILES_GENERATION = "swift.split_derived_files_generation"
+
+# If enabled the skip function bodies frontend flag is passed when using derived
+# files generation. This requires Swift 5.2
+SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES = "swift.skip_function_bodies_for_derived_files"
diff --git a/swift/internal/swift_autoconfiguration.bzl b/swift/internal/swift_autoconfiguration.bzl
index 48b772acf..dbcf1af9b 100644
--- a/swift/internal/swift_autoconfiguration.bzl
+++ b/swift/internal/swift_autoconfiguration.bzl
@@ -28,6 +28,7 @@ load(
     "@build_bazel_rules_swift//swift/internal:feature_names.bzl",
     "SWIFT_FEATURE_DEBUG_PREFIX_MAP",
     "SWIFT_FEATURE_ENABLE_BATCH_MODE",
+    "SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES",
     "SWIFT_FEATURE_IMPLICIT_MODULES",
     "SWIFT_FEATURE_MODULE_MAP_NO_PRIVATE_HEADERS",
     "SWIFT_FEATURE_SUPPORTS_PRIVATE_DEPS",
@@ -75,6 +76,15 @@ def _check_enable_batch_mode(repository_ctx, swiftc_path, temp_dir):
         "-enable-batch-mode",
     )
 
+def _check_skip_function_bodies(repository_ctx, swiftc_path, temp_dir):
+    """Returns True if `swiftc` supports skip function bodies."""
+    return _swift_succeeds(
+        repository_ctx,
+        swiftc_path,
+        "-version",
+        "-experimental-skip-non-inlinable-function-bodies",
+    )
+
 def _check_debug_prefix_map(repository_ctx, swiftc_path, temp_dir):
     """Returns True if `swiftc` supports debug prefix mapping."""
     return _swift_succeeds(
@@ -187,6 +197,7 @@ def _compute_feature_values(repository_ctx, swiftc_path):
 _FEATURE_CHECKS = {
     SWIFT_FEATURE_DEBUG_PREFIX_MAP: _check_debug_prefix_map,
     SWIFT_FEATURE_ENABLE_BATCH_MODE: _check_enable_batch_mode,
+    SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES: _check_skip_function_bodies,
     SWIFT_FEATURE_SUPPORTS_PRIVATE_DEPS: _check_supports_private_deps,
     SWIFT_FEATURE_USE_RESPONSE_FILES: _check_use_response_files,
 }
diff --git a/swift/internal/swift_toolchain.bzl b/swift/internal/swift_toolchain.bzl
index 40e0ee879..c975787bc 100644
--- a/swift/internal/swift_toolchain.bzl
+++ b/swift/internal/swift_toolchain.bzl
@@ -59,6 +59,15 @@ def _all_tool_configs(
     """
     _swift_driver_tool_config = swift_toolchain_config.driver_tool_config
 
+    compile_tool_config = _swift_driver_tool_config(
+        driver_mode = "swiftc",
+        swift_executable = swift_executable,
+        toolchain_root = toolchain_root,
+        use_param_file = use_param_file,
+        worker_mode = "persistent",
+        additional_tools = additional_tools,
+    )
+
     return {
         swift_action_names.AUTOLINK_EXTRACT: _swift_driver_tool_config(
             driver_mode = "swift-autolink-extract",
@@ -67,14 +76,8 @@ def _all_tool_configs(
             worker_mode = "wrap",
             additional_tools = additional_tools,
         ),
-        swift_action_names.COMPILE: _swift_driver_tool_config(
-            driver_mode = "swiftc",
-            swift_executable = swift_executable,
-            toolchain_root = toolchain_root,
-            use_param_file = use_param_file,
-            worker_mode = "persistent",
-            additional_tools = additional_tools,
-        ),
+        swift_action_names.COMPILE: compile_tool_config,
+        swift_action_names.DERIVE_FILES: compile_tool_config,
         swift_action_names.MODULEWRAP: _swift_driver_tool_config(
             # This must come first after the driver name.
             args = ["-modulewrap"],
diff --git a/swift/internal/xcode_swift_toolchain.bzl b/swift/internal/xcode_swift_toolchain.bzl
index 4e0209835..5a0d2a6cf 100644
--- a/swift/internal/xcode_swift_toolchain.bzl
+++ b/swift/internal/xcode_swift_toolchain.bzl
@@ -34,6 +34,7 @@ load(
     "SWIFT_FEATURE_BUNDLED_XCTESTS",
     "SWIFT_FEATURE_DEBUG_PREFIX_MAP",
     "SWIFT_FEATURE_ENABLE_BATCH_MODE",
+    "SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES",
     "SWIFT_FEATURE_MODULE_MAP_HOME_IS_CWD",
     "SWIFT_FEATURE_MODULE_MAP_NO_PRIVATE_HEADERS",
     "SWIFT_FEATURE_SUPPORTS_LIBRARY_EVOLUTION",
@@ -287,6 +288,7 @@ def _all_action_configs(
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -317,6 +319,7 @@ def _all_action_configs(
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [swift_toolchain_config.add_arg("-embed-bitcode")],
@@ -325,6 +328,7 @@ def _all_action_configs(
         swift_toolchain_config.action_config(
             actions = [
                 swift_action_names.COMPILE,
+                swift_action_names.DERIVE_FILES,
                 swift_action_names.PRECOMPILE_C_MODULE,
             ],
             configurators = [
@@ -342,6 +346,7 @@ def _all_action_configs(
             swift_toolchain_config.action_config(
                 actions = [
                     swift_action_names.COMPILE,
+                    swift_action_names.DERIVE_FILES,
                     swift_action_names.PRECOMPILE_C_MODULE,
                 ],
                 configurators = [
@@ -389,16 +394,19 @@ def _all_tool_configs(
         env = dict(env)
         env["TOOLCHAINS"] = custom_toolchain
 
+    tool_config = swift_toolchain_config.driver_tool_config(
+        driver_mode = "swiftc",
+        env = env,
+        execution_requirements = execution_requirements,
+        swift_executable = swift_executable,
+        toolchain_root = toolchain_root,
+        use_param_file = use_param_file,
+        worker_mode = "persistent",
+    )
+
     tool_configs = {
-        swift_action_names.COMPILE: swift_toolchain_config.driver_tool_config(
-            driver_mode = "swiftc",
-            env = env,
-            execution_requirements = execution_requirements,
-            swift_executable = swift_executable,
-            toolchain_root = toolchain_root,
-            use_param_file = use_param_file,
-            worker_mode = "persistent",
-        ),
+        swift_action_names.COMPILE: tool_config,
+        swift_action_names.DERIVE_FILES: tool_config,
     }
 
     # Xcode 12.0 implies Swift 5.3.
@@ -594,6 +602,10 @@ def _xcode_swift_toolchain_impl(ctx):
         requested_features.append(SWIFT_FEATURE_SUPPORTS_LIBRARY_EVOLUTION)
         requested_features.append(SWIFT_FEATURE_SUPPORTS_PRIVATE_DEPS)
 
+    # Xcode 11.4 implies Swift 5.2.
+    if _is_xcode_at_least_version(xcode_config, "11.4"):
+        requested_features.append(SWIFT_FEATURE_ENABLE_SKIP_FUNCTION_BODIES)
+
     command_line_copts = _command_line_objc_copts(
         ctx.var["COMPILATION_MODE"],
         ctx.fragments.objc,
diff --git a/test/BUILD b/test/BUILD
index ea685d048..70dcb37e7 100644
--- a/test/BUILD
+++ b/test/BUILD
@@ -4,6 +4,7 @@ load(":coverage_settings_tests.bzl", "coverage_settings_test_suite")
 load(":generated_header_tests.bzl", "generated_header_test_suite")
 load(":private_deps_tests.bzl", "private_deps_test_suite")
 load(":swift_through_non_swift_tests.bzl", "swift_through_non_swift_test_suite")
+load(":split_derived_files_tests.bzl", "split_derived_files_test_suite")
 
 licenses(["notice"])
 
@@ -17,6 +18,8 @@ private_deps_test_suite()
 
 swift_through_non_swift_test_suite()
 
+split_derived_files_test_suite()
+
 test_suite(
     name = "all_tests",
 )
diff --git a/test/split_derived_files_tests.bzl b/test/split_derived_files_tests.bzl
new file mode 100644
index 000000000..89baa9b47
--- /dev/null
+++ b/test/split_derived_files_tests.bzl
@@ -0,0 +1,226 @@
+"""Tests for derived files related command line flags under various configs."""
+
+load(
+    "@build_bazel_rules_swift//test/rules:action_command_line_test.bzl",
+    "make_action_command_line_test_rule",
+)
+load(
+    "@build_bazel_rules_swift//test/rules:provider_test.bzl",
+    "make_provider_test_rule",
+)
+
+default_no_split_test = make_action_command_line_test_rule()
+default_no_split_provider_test = make_provider_test_rule()
+split_swiftmodule_test = make_action_command_line_test_rule(
+    config_settings = {
+        "//command_line_option:features": [
+            "swift.split_derived_files_generation",
+        ],
+    },
+)
+split_swiftmodule_provider_test = make_provider_test_rule(
+    config_settings = {
+        "//command_line_option:features": [
+            "swift.split_derived_files_generation",
+        ],
+    },
+)
+split_swiftmodule_wmo_test = make_action_command_line_test_rule(
+    config_settings = {
+        "//command_line_option:swiftcopt": [
+            "-whole-module-optimization",
+        ],
+        "//command_line_option:features": [
+            "swift.split_derived_files_generation",
+        ],
+    },
+)
+split_swiftmodule_wmo_provider_test = make_provider_test_rule(
+    config_settings = {
+        "//command_line_option:swiftcopt": [
+            "-whole-module-optimization",
+        ],
+        "//command_line_option:features": [
+            "swift.split_derived_files_generation",
+        ],
+    },
+)
+split_swiftmodule_skip_function_bodies_test = make_action_command_line_test_rule(
+    config_settings = {
+        "//command_line_option:swiftcopt": [
+            "-whole-module-optimization",
+        ],
+        "//command_line_option:features": [
+            "swift.split_derived_files_generation",
+            "swift.enable_skip_function_bodies",
+        ],
+    },
+)
+
+def split_derived_files_test_suite(name = "split_derived_files"):
+    """Test suite for split derived files options.
+
+    Args:
+        name: The name prefix for all the nested tests
+    """
+    default_no_split_test(
+        name = "{}_default_no_split_args".format(name),
+        expected_argv = [
+            "-emit-module-path",
+            "-emit-object",
+        ],
+        mnemonic = "SwiftCompile",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    default_no_split_provider_test(
+        name = "{}_default_no_split_provider".format(name),
+        expected_files = [
+            "test_fixtures_debug_settings_simple.swiftmodule",
+        ],
+        field = "direct_modules.swift.swiftmodule",
+        provider = "SwiftInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    default_no_split_provider_test(
+        name = "{}_default_no_split_provider_ccinfo".format(name),
+        expected_files = [
+            "libsimple.a",
+        ],
+        field = "linking_context.libraries_to_link.pic_static_library!",
+        provider = "CcInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_test(
+        name = "{}_object_only".format(name),
+        expected_argv = [
+            "-emit-object",
+        ],
+        mnemonic = "SwiftCompile",
+        not_expected_argv = [
+            "-emit-module-path",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_test(
+        name = "{}_swiftmodule_only".format(name),
+        expected_argv = [
+            "-emit-module-path",
+        ],
+        mnemonic = "SwiftDeriveFiles",
+        not_expected_argv = [
+            "-emit-object",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_provider_test(
+        name = "{}_split_provider".format(name),
+        expected_files = [
+            "test_fixtures_debug_settings_simple.swiftmodule",
+        ],
+        field = "direct_modules.swift.swiftmodule",
+        provider = "SwiftInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_provider_test(
+        name = "{}_split_provider_ccinfo".format(name),
+        expected_files = [
+            "libsimple.a",
+        ],
+        field = "linking_context.libraries_to_link.pic_static_library!",
+        provider = "CcInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_wmo_test(
+        name = "{}_object_only_wmo".format(name),
+        expected_argv = [
+            "-emit-object",
+            "-whole-module-optimization",
+        ],
+        mnemonic = "SwiftCompile",
+        not_expected_argv = [
+            "-emit-module-path",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_wmo_test(
+        name = "{}_swiftmodule_only_wmo".format(name),
+        expected_argv = [
+            "-emit-module-path",
+            "-whole-module-optimization",
+        ],
+        mnemonic = "SwiftDeriveFiles",
+        not_expected_argv = [
+            "-emit-object",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_wmo_provider_test(
+        name = "{}_split_wmo_provider".format(name),
+        expected_files = [
+            "test_fixtures_debug_settings_simple.swiftmodule",
+        ],
+        field = "direct_modules.swift.swiftmodule",
+        provider = "SwiftInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_wmo_provider_test(
+        name = "{}_split_wmo_provider_ccinfo".format(name),
+        expected_files = [
+            "libsimple.a",
+        ],
+        field = "linking_context.libraries_to_link.pic_static_library!",
+        provider = "CcInfo",
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_skip_function_bodies_test(
+        name = "{}_no_skip_function_bodies".format(name),
+        expected_argv = [
+            "-emit-object",
+        ],
+        mnemonic = "SwiftCompile",
+        not_expected_argv = [
+            "-experimental-skip-non-inlinable-function-bodies",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    split_swiftmodule_skip_function_bodies_test(
+        name = "{}_skip_function_bodies".format(name),
+        expected_argv = [
+            "-experimental-skip-non-inlinable-function-bodies",
+        ],
+        mnemonic = "SwiftDeriveFiles",
+        not_expected_argv = [
+            "-emit-object",
+        ],
+        tags = [name],
+        target_under_test = "@build_bazel_rules_swift//test/fixtures/debug_settings:simple",
+    )
+
+    native.test_suite(
+        name = name,
+        tags = [name],
+    )