diff --git a/include/swift/AST/DiagnosticsFrontend.def b/include/swift/AST/DiagnosticsFrontend.def
index d9c4fd7e074..080d8d7cac5 100644
--- a/include/swift/AST/DiagnosticsFrontend.def
+++ b/include/swift/AST/DiagnosticsFrontend.def
@@ -110,6 +110,8 @@ ERROR(error_cannot_direct_cc1_pcm_build_in_mode,none,
       "'-direct-clang-cc1-module-build' only supported when building a PCM ('-emit-pcm')'", ())
 ERROR(error_unsupported_option_argument,none,
       "unsupported argument '%1' to option '%0'", (StringRef, StringRef))
+ERROR(error_swift_module_file_requires_delimeter,none,
+      "-swift-module-file= argument requires format <name>=<path>, got: '%0'", (StringRef))
 ERROR(error_immediate_mode_missing_stdlib,none,
       "could not load the swift standard library", ())
 ERROR(error_immediate_mode_missing_library,none,
diff --git a/include/swift/AST/ModuleDependencies.h b/include/swift/AST/ModuleDependencies.h
index 434f48282c9..66fbe9938c1 100644
--- a/include/swift/AST/ModuleDependencies.h
+++ b/include/swift/AST/ModuleDependencies.h
@@ -150,7 +150,7 @@ public:
 
   /// The Swift frontend invocation arguments to build the Swift module from the
   /// interface.
-  const std::vector<std::string> buildCommandLine;
+  std::vector<std::string> buildCommandLine;
 
   /// The hash value that will be used for the generated module
   const std::string contextHash;
@@ -186,6 +186,10 @@ public:
   static bool classof(const ModuleDependencyInfoStorageBase *base) {
     return base->dependencyKind == ModuleDependencyKind::SwiftInterface;
   }
+
+  void updateCommandLine(const std::vector<std::string> &newCommandLine) {
+    buildCommandLine = newCommandLine;
+  }
 };
 
 /// Describes the dependencies of a Swift module
@@ -433,6 +437,11 @@ public:
     storage->resolvedModuleDependencies.assign(dependencyIDs.begin(), dependencyIDs.end());
   }
 
+  void updateCommandLine(const std::vector<std::string> &newCommandLine) {
+    assert(isSwiftInterfaceModule() && "Can only update command line on Swift interface dependency");
+    cast<SwiftInterfaceModuleDependenciesStorage>(storage.get())->updateCommandLine(newCommandLine);
+  }
+
   bool isResolved() const {
     return storage->resolved;
   }
@@ -752,4 +761,17 @@ public:
 
 } // namespace swift
 
+namespace std {
+template <>
+struct hash<swift::ModuleDependencyID> {
+  using UnderlyingKindType = std::underlying_type<swift::ModuleDependencyKind>::type;
+  std::size_t operator()(const swift::ModuleDependencyID &id) const {
+    auto underlyingKindValue = static_cast<UnderlyingKindType>(id.second);
+
+    return (hash<string>()(id.first) ^
+            (hash<UnderlyingKindType>()(underlyingKindValue)));
+  }
+};
+} // namespace std
+
 #endif /* SWIFT_AST_MODULE_DEPENDENCIES_H */
diff --git a/include/swift/AST/SearchPathOptions.h b/include/swift/AST/SearchPathOptions.h
index ab8b0d23ff3..e1d68dc50c2 100644
--- a/include/swift/AST/SearchPathOptions.h
+++ b/include/swift/AST/SearchPathOptions.h
@@ -355,6 +355,10 @@ public:
   /// A map of explicit Swift module information.
   std::string ExplicitSwiftModuleMap;
 
+  /// Module inputs specified with -swift-module-input,
+  /// <ModuleName, Path to .swiftmodule file>
+  std::vector<std::pair<std::string, std::string>> ExplicitSwiftModuleInputs;
+
   /// A map of placeholder Swift module dependency information.
   std::string PlaceholderDependencyModuleMap;
 
diff --git a/include/swift/Frontend/ModuleInterfaceLoader.h b/include/swift/Frontend/ModuleInterfaceLoader.h
index ee16da87208..a1546384d0c 100644
--- a/include/swift/Frontend/ModuleInterfaceLoader.h
+++ b/include/swift/Frontend/ModuleInterfaceLoader.h
@@ -129,7 +129,8 @@ class SearchPathOptions;
 class CompilerInvocation;
 
 /// A ModuleLoader that loads explicitly built Swift modules specified via
-/// -swift-module-file
+/// -swift-module-file or modules found in a provided
+/// -explicit-swift-module-map-file JSON input.
 class ExplicitSwiftModuleLoader: public SerializedModuleLoaderBase {
   explicit ExplicitSwiftModuleLoader(ASTContext &ctx, DependencyTracker *tracker,
                                      ModuleLoadingMode loadMode,
@@ -164,6 +165,7 @@ public:
   create(ASTContext &ctx,
          DependencyTracker *tracker, ModuleLoadingMode loadMode,
          StringRef ExplicitSwiftModuleMap,
+         const std::vector<std::pair<std::string, std::string>> &ExplicitSwiftModuleInputs,
          bool IgnoreSwiftSourceInfoFile);
 
   /// Append visible module names to \p names. Note that names are possibly
diff --git a/include/swift/Option/FrontendOptions.td b/include/swift/Option/FrontendOptions.td
index 6938ce5fa4c..a4294a76de8 100644
--- a/include/swift/Option/FrontendOptions.td
+++ b/include/swift/Option/FrontendOptions.td
@@ -185,6 +185,10 @@ def disable_typo_correction : Flag<["-"], "disable-typo-correction">,
 def disable_implicit_swift_modules: Flag<["-"], "disable-implicit-swift-modules">,
   HelpText<"Disable building Swift modules implicitly by the compiler">;
 
+def swift_module_file: Joined<["-"], "swift-module-file=">,
+  MetaVarName<"<name>=<path>">,
+  HelpText<"Specify Swift module input explicitly built from textual interface">;
+
 def explicit_swift_module_map
   : Separate<["-"], "explicit-swift-module-map-file">, MetaVarName<"<path>">,
     HelpText<"Specify a JSON file containing information of explicit Swift modules">;
diff --git a/lib/ClangImporter/ClangModuleDependencyScanner.cpp b/lib/ClangImporter/ClangModuleDependencyScanner.cpp
index 29f47d1e9b4..6e0349a4b3b 100644
--- a/lib/ClangImporter/ClangModuleDependencyScanner.cpp
+++ b/lib/ClangImporter/ClangModuleDependencyScanner.cpp
@@ -153,15 +153,15 @@ void ClangImporter::recordModuleDependencies(
     // We are using Swift frontend mode.
     swiftArgs.push_back("-frontend");
 
-    // We pass the entire argument list via -Xcc, so the invocation should
-    // use extra clang options alone.
-    swiftArgs.push_back("-only-use-extra-clang-opts");
-
     // Swift frontend action: -emit-pcm
     swiftArgs.push_back("-emit-pcm");
     swiftArgs.push_back("-module-name");
     swiftArgs.push_back(clangModuleDep.ID.ModuleName);
 
+    // We pass the entire argument list via -Xcc, so the invocation should
+    // use extra clang options alone.
+    swiftArgs.push_back("-only-use-extra-clang-opts");
+
     auto pcmPath = moduleCacheRelativeLookupModuleOutput(
         clangModuleDep.ID, ModuleOutputKind::ModuleFile,
         getModuleCachePathFromClang(getClangInstance()));
diff --git a/lib/DependencyScan/ModuleDependencyCacheSerialization.cpp b/lib/DependencyScan/ModuleDependencyCacheSerialization.cpp
index 6140d903642..f9e749c04a4 100644
--- a/lib/DependencyScan/ModuleDependencyCacheSerialization.cpp
+++ b/lib/DependencyScan/ModuleDependencyCacheSerialization.cpp
@@ -656,19 +656,6 @@ struct llvm::DenseMapInfo<ModuleIdentifierArrayKind> {
   }
 };
 
-namespace std {
-template <>
-struct hash<ModuleDependencyID> {
-  using UnderlyingKindType = std::underlying_type<ModuleDependencyKind>::type;
-  std::size_t operator()(const ModuleDependencyID &id) const {
-    auto underlyingKindValue = static_cast<UnderlyingKindType>(id.second);
-
-    return (hash<string>()(id.first) ^
-            (hash<UnderlyingKindType>()(underlyingKindValue)));
-  }
-};
-} // namespace std
-
 namespace swift {
 
 class ModuleDependenciesCacheSerializer {
diff --git a/lib/DependencyScan/ScanDependencies.cpp b/lib/DependencyScan/ScanDependencies.cpp
index b2a1e1a426d..23345444ac9 100644
--- a/lib/DependencyScan/ScanDependencies.cpp
+++ b/lib/DependencyScan/ScanDependencies.cpp
@@ -36,6 +36,7 @@
 #include "swift/Strings.h"
 #include "clang/Basic/Module.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SetOperations.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
@@ -47,6 +48,7 @@
 #include <set>
 #include <string>
 #include <sstream>
+#include <algorithm>
 
 using namespace swift;
 using namespace swift::dependencies;
@@ -157,6 +159,149 @@ static void findAllImportedClangModules(ASTContext &ctx, StringRef moduleName,
   }
 }
 
+// Get all dependencies's IDs of this module from its cached
+// ModuleDependencyInfo
+static ArrayRef<ModuleDependencyID>
+getDependencies(const ModuleDependencyID &moduleID,
+                const ModuleDependenciesCache &cache) {
+  const auto &optionalModuleInfo =
+      cache.findDependency(moduleID.first, moduleID.second);
+  assert(optionalModuleInfo.has_value());
+  return optionalModuleInfo.value()->getModuleDependencies();
+}
+
+/// Implements a topological sort via recursion and reverse postorder DFS.
+/// Does not bother handling cycles, relying on a DAG guarantee by the client.
+static std::vector<ModuleDependencyID>
+computeTopologicalSortOfExplicitDependencies(
+    const ModuleDependencyIDSetVector &allModules,
+    const ModuleDependenciesCache &cache) {
+  std::unordered_set<ModuleDependencyID> visited;
+  std::vector<ModuleDependencyID> result;
+  std::stack<ModuleDependencyID> stack;
+
+  // Must be explicitly-typed to allow recursion
+  std::function<void(const ModuleDependencyID &)> visit;
+  visit = [&visit, &cache, &visited, &result,
+           &stack](const ModuleDependencyID &moduleID) {
+    // Mark this node as visited -- we are done if it already was.
+    if (!visited.insert(moduleID).second)
+      return;
+
+    // Otherwise, visit each adjacent node.
+    for (const auto &succID : getDependencies(moduleID, cache)) {
+      // We don't worry if successor is already in this current stack,
+      // since that would mean we have found a cycle, which should not
+      // be possible because we checked for cycles earlier.
+      stack.push(succID);
+      visit(succID);
+      auto top = stack.top();
+      stack.pop();
+      assert(top == succID);
+    }
+
+    // Add to the result.
+    result.push_back(moduleID);
+  };
+
+  for (const auto &modID : allModules) {
+    assert(stack.empty());
+    stack.push(modID);
+    visit(modID);
+    auto top = stack.top();
+    stack.pop();
+    assert(top == modID);
+  }
+
+  std::reverse(result.begin(), result.end());
+  return result;
+}
+
+/// For each module in the graph, compute a set of all its dependencies,
+/// direct *and* transitive.
+static std::unordered_map<ModuleDependencyID,
+                          std::set<ModuleDependencyID>>
+computeTransitiveClosureOfExplicitDependencies(
+    const std::vector<ModuleDependencyID> &topologicallySortedModuleList,
+    const ModuleDependenciesCache &cache) {
+  // The usage of an ordered ::set is important to ensure the
+  // dependencies are listed in a deterministic order.
+  std::unordered_map<ModuleDependencyID, std::set<ModuleDependencyID>>
+      result;
+  for (const auto &modID : topologicallySortedModuleList)
+    result[modID] = {modID};
+
+  // Traverse the set of modules in reverse topological order, assimilating
+  // transitive closures
+  for (auto it = topologicallySortedModuleList.rbegin(),
+            end = topologicallySortedModuleList.rend();
+       it != end; ++it) {
+    const auto &modID = *it;
+    auto &modReachableSet = result[modID];
+    for (const auto &succID : getDependencies(modID, cache)) {
+      const auto &succReachableSet = result[succID];
+      llvm::set_union(modReachableSet, succReachableSet);
+    }
+  }
+  return result;
+}
+
+static void
+resolveExplicitModuleInputs(ModuleDependencyID moduleID,
+                            const ModuleDependencyInfo &resolvingDepInfo,
+                            const std::set<ModuleDependencyID> &dependencies,
+                            ModuleDependenciesCache &cache) {
+  auto resolvingInterfaceDepDetails =
+      resolvingDepInfo.getAsSwiftInterfaceModule();
+  assert(resolvingInterfaceDepDetails &&
+         "Expected Swift Interface dependency.");
+
+  auto commandLine = resolvingInterfaceDepDetails->buildCommandLine;
+  for (const auto &depModuleID : dependencies) {
+    const auto optionalDepInfo =
+        cache.findDependency(depModuleID.first, depModuleID.second);
+    assert(optionalDepInfo.has_value());
+    const auto depInfo = optionalDepInfo.value();
+    switch (depModuleID.second) {
+    case swift::ModuleDependencyKind::SwiftInterface: {
+      auto interfaceDepDetails = depInfo->getAsSwiftInterfaceModule();
+      assert(interfaceDepDetails && "Expected Swift Interface dependency.");
+      commandLine.push_back("-swift-module-file=" + depModuleID.first + "=" +
+                            interfaceDepDetails->moduleOutputPath);
+    } break;
+    case swift::ModuleDependencyKind::SwiftBinary: {
+      auto binaryDepDetails = depInfo->getAsSwiftBinaryModule();
+      assert(binaryDepDetails && "Expected Swift Binary Module dependency.");
+      commandLine.push_back("-swift-module-file=" + depModuleID.first + "=" +
+                            binaryDepDetails->compiledModulePath);
+    } break;
+    case swift::ModuleDependencyKind::SwiftPlaceholder: {
+      auto placeholderDetails = depInfo->getAsPlaceholderDependencyModule();
+      assert(placeholderDetails && "Expected Swift Placeholder dependency.");
+      commandLine.push_back("-swift-module-file=" + depModuleID.first + "=" +
+                            placeholderDetails->compiledModulePath);
+    } break;
+    case swift::ModuleDependencyKind::Clang: {
+      auto clangDepDetails = depInfo->getAsClangModule();
+      assert(clangDepDetails && "Expected Clang Module dependency.");
+      commandLine.push_back("-Xcc");
+      commandLine.push_back("-fmodule-file=" + depModuleID.first + "=" +
+                            clangDepDetails->pcmOutputPath);
+      commandLine.push_back("-Xcc");
+      commandLine.push_back("-fmodule-map-file=" +
+                            clangDepDetails->moduleMapFile);
+    } break;
+    default:
+      llvm_unreachable("Unhandled dependency kind.");
+    }
+  }
+
+  // Update the dependency in the cache with the modified command-line.
+  auto dependencyInfoCopy = resolvingDepInfo;
+  dependencyInfoCopy.updateCommandLine(commandLine);
+  cache.updateDependency(moduleID, dependencyInfoCopy);
+}
+
 /// Resolve the direct dependencies of the given module.
 static ArrayRef<ModuleDependencyID>
 resolveDirectDependencies(CompilerInstance &instance, ModuleDependencyID module,
@@ -1475,8 +1620,29 @@ swift::dependencies::performModuleScan(CompilerInstance &instance,
   if (diagnoseCycle(instance, cache, mainModuleID, ASTDelegate))
     return std::make_error_code(std::errc::not_supported);
 
+  // Resolve Swift dependency command-line arguments
+  // Must happen after cycle detection, because it relies on
+  // the DAG property of the dependency graph.
+  auto topoSortedModuleList =
+      computeTopologicalSortOfExplicitDependencies(allModules, cache);
+  auto moduleTransitiveClosures =
+      computeTransitiveClosureOfExplicitDependencies(topoSortedModuleList,
+                                                     cache);
+  for (const auto &dependencyClosure : moduleTransitiveClosures) {
+    auto &modID = dependencyClosure.first;
+    // For main module or binary modules, no command-line to resolve.
+    // For Clang modules, their dependencies are resolved by the clang Scanner
+    // itself for us.
+    if (modID.second != ModuleDependencyKind::SwiftInterface)
+      continue;
+    auto optionalDeps = cache.findDependency(modID.first, modID.second);
+    assert(optionalDeps.has_value());
+    auto deps = optionalDeps.value();
+    resolveExplicitModuleInputs(modID, *deps, dependencyClosure.second, cache);
+  }
+
   auto dependencyGraph = generateFullDependencyGraph(
-      instance, cache, ASTDelegate, allModules.getArrayRef());
+      instance, cache, ASTDelegate, topoSortedModuleList);
   // Update the dependency tracker.
   if (auto depTracker = instance.getDependencyTracker()) {
     for (auto module : allModules) {
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 18686bc5e71..21064e9bc8a 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1363,6 +1363,25 @@ static void ParseSymbolGraphArgs(symbolgraphgen::SymbolGraphOptions &Opts,
   Opts.IncludeClangDocs = false;
 }
 
+static bool validateSwiftModuleFileArgumentAndAdd(const std::string &swiftModuleArgument,
+                                                  DiagnosticEngine &Diags,
+                                                  std::vector<std::pair<std::string, std::string>> &ExplicitSwiftModuleInputs) {
+  std::size_t foundDelimeterPos = swiftModuleArgument.find_first_of("=");
+  if (foundDelimeterPos == std::string::npos) {
+    Diags.diagnose(SourceLoc(), diag::error_swift_module_file_requires_delimeter,
+                   swiftModuleArgument);
+    return true;
+  }
+  std::string moduleName = swiftModuleArgument.substr(0, foundDelimeterPos),
+              modulePath = swiftModuleArgument.substr(foundDelimeterPos+1);
+  if (!Lexer::isIdentifier(moduleName)) {
+    Diags.diagnose(SourceLoc(), diag::error_bad_module_name, moduleName, false);
+    return true;
+  }
+  ExplicitSwiftModuleInputs.emplace_back(std::make_pair(moduleName, modulePath));
+  return false;
+}
+
 static bool ParseSearchPathArgs(SearchPathOptions &Opts,
                                 ArgList &Args,
                                 DiagnosticEngine &Diags,
@@ -1415,6 +1434,11 @@ static bool ParseSearchPathArgs(SearchPathOptions &Opts,
 
   if (const Arg *A = Args.getLastArg(OPT_explicit_swift_module_map))
     Opts.ExplicitSwiftModuleMap = A->getValue();
+  for (auto A : Args.getAllArgValues(options::OPT_swift_module_file)) {
+    if (validateSwiftModuleFileArgumentAndAdd(A, Diags,
+                                              Opts.ExplicitSwiftModuleInputs))
+      return true;
+  }
   for (auto A: Args.filtered(OPT_candidate_module_file)) {
     Opts.CandidateCompiledModules.push_back(resolveSearchPath(A->getValue()));
   }
diff --git a/lib/Frontend/Frontend.cpp b/lib/Frontend/Frontend.cpp
index c83b6986a9d..e15e81b133a 100644
--- a/lib/Frontend/Frontend.cpp
+++ b/lib/Frontend/Frontend.cpp
@@ -566,10 +566,12 @@ bool CompilerInstance::setUpModuleLoaders() {
   bool ExplicitModuleBuild =
       Invocation.getFrontendOptions().DisableImplicitModules;
   if (ExplicitModuleBuild ||
-      !Invocation.getSearchPathOptions().ExplicitSwiftModuleMap.empty()) {
+      !Invocation.getSearchPathOptions().ExplicitSwiftModuleMap.empty() ||
+      !Invocation.getSearchPathOptions().ExplicitSwiftModuleInputs.empty()) {
     ESML = ExplicitSwiftModuleLoader::create(
         *Context, getDependencyTracker(), MLM,
         Invocation.getSearchPathOptions().ExplicitSwiftModuleMap,
+        Invocation.getSearchPathOptions().ExplicitSwiftModuleInputs,
         IgnoreSourceInfoFile);
   }
 
diff --git a/lib/Frontend/ModuleInterfaceLoader.cpp b/lib/Frontend/ModuleInterfaceLoader.cpp
index e1ca8adfc76..977098482f7 100644
--- a/lib/Frontend/ModuleInterfaceLoader.cpp
+++ b/lib/Frontend/ModuleInterfaceLoader.cpp
@@ -1897,6 +1897,16 @@ struct ExplicitSwiftModuleLoader::Implementation {
       }
     }
   }
+
+  void addCommandLineExplicitInputs(
+      const std::vector<std::pair<std::string, std::string>>
+          &commandLineExplicitInputs) {
+    for (const auto &moduleInput : commandLineExplicitInputs) {
+      ExplicitModuleInfo entry;
+      entry.modulePath = moduleInput.second;
+      ExplicitModuleMap.try_emplace(moduleInput.first, std::move(entry));
+    }
+  }
 };
 
 ExplicitSwiftModuleLoader::ExplicitSwiftModuleLoader(
@@ -2057,6 +2067,7 @@ std::unique_ptr<ExplicitSwiftModuleLoader>
 ExplicitSwiftModuleLoader::create(ASTContext &ctx,
     DependencyTracker *tracker, ModuleLoadingMode loadMode,
     StringRef ExplicitSwiftModuleMap,
+    const std::vector<std::pair<std::string, std::string>> &ExplicitSwiftModuleInputs,
     bool IgnoreSwiftSourceInfoFile) {
   auto result = std::unique_ptr<ExplicitSwiftModuleLoader>(
     new ExplicitSwiftModuleLoader(ctx, tracker, loadMode,
@@ -2067,6 +2078,11 @@ ExplicitSwiftModuleLoader::create(ASTContext &ctx,
     // Parse a JSON file to collect explicitly built modules.
     Impl.parseSwiftExplicitModuleMap(ExplicitSwiftModuleMap);
   }
+  // If some modules are provided with explicit
+  // '-swift-module-file' options, add those as well.
+  if (!ExplicitSwiftModuleInputs.empty()) {
+    Impl.addCommandLineExplicitInputs(ExplicitSwiftModuleInputs);
+  }
 
   return result;
 }
diff --git a/lib/Serialization/ModuleDependencyScanner.cpp b/lib/Serialization/ModuleDependencyScanner.cpp
index a89c29b16f4..3197e41920e 100644
--- a/lib/Serialization/ModuleDependencyScanner.cpp
+++ b/lib/Serialization/ModuleDependencyScanner.cpp
@@ -112,21 +112,38 @@ ErrorOr<ModuleDependencyInfo> ModuleDependencyScanner::scanInterfaceFile(
                                               StringRef(),
                                               SourceLoc(),
                 [&](ASTContext &Ctx, ModuleDecl *mainMod,
-                    ArrayRef<StringRef> Args,
+                    ArrayRef<StringRef> BaseArgs,
                     ArrayRef<StringRef> PCMArgs, StringRef Hash) {
     assert(mainMod);
     std::string InPath = moduleInterfacePath.str();
     auto compiledCandidates = getCompiledCandidates(Ctx, realModuleName.str(),
                                                     InPath);
+    std::vector<std::string> Args(BaseArgs.begin(), BaseArgs.end());
 
+    // Add explicit Swift dependency compilation flags
+    Args.push_back("-explicit-interface-module-build");
+    Args.push_back("-disable-implicit-swift-modules");
+    Args.push_back("-Xcc"); Args.push_back("-fno-implicit-modules");
+    Args.push_back("-Xcc"); Args.push_back("-fno-implicit-module-maps");
+    for (const auto &candidate : compiledCandidates) {
+      Args.push_back("-candidate-module-file");
+      Args.push_back(candidate);
+    }
+
+    // Compute the output path and add it to the command line
     SmallString<128> outputPathBase(moduleCachePath);
     llvm::sys::path::append(
         outputPathBase,
         moduleName.str() + "-" + Hash + "." +
             file_types::getExtension(file_types::TY_SwiftModuleFile));
+    Args.push_back("-o");
+    Args.push_back(outputPathBase.str().str());
+
+    std::vector<StringRef> ArgsRefs(Args.begin(), Args.end());
     Result = ModuleDependencyInfo::forSwiftInterfaceModule(
-        outputPathBase.str().str(), InPath, compiledCandidates, Args, PCMArgs,
+        outputPathBase.str().str(), InPath, compiledCandidates, ArgsRefs, PCMArgs,
         Hash, isFramework);
+
     // Open the interface file.
     auto &fs = *Ctx.SourceMgr.getFileSystem();
     auto interfaceBuf = fs.getBufferForFile(moduleInterfacePath);
diff --git a/test/ScanDependencies/explicit-swift-dependencies.swift b/test/ScanDependencies/explicit-swift-dependencies.swift
new file mode 100644
index 00000000000..185a20750a9
--- /dev/null
+++ b/test/ScanDependencies/explicit-swift-dependencies.swift
@@ -0,0 +1,55 @@
+// RUN: %empty-directory(%t)
+// RUN: mkdir -p %t/clang-module-cache
+
+// RUN: %target-swift-frontend -scan-dependencies -module-cache-path %t/clang-module-cache %s -o %t/deps.json -I %S/Inputs/CHeaders -I %S/Inputs/Swift -emit-dependencies -emit-dependencies-path %t/deps.d -import-objc-header %S/Inputs/CHeaders/Bridging.h -swift-version 4
+// Check the contents of the JSON output
+// RUN: %FileCheck %s < %t/deps.json
+
+// REQUIRES: executable_test
+// REQUIRES: objc_interop
+
+
+import F
+
+// CHECK: "mainModuleName": "deps"
+
+/// --------Main module
+// CHECK-LABEL: "modulePath": "deps.swiftmodule",
+// CHECK-NEXT: sourceFiles
+// CHECK-NEXT: explicit-swift-dependencies.swift
+// CHECK-NEXT: ],
+// CHECK-NEXT: "directDependencies": [
+// CHECK-DAG:     "swift": "F"
+// CHECK-DAG:     "swift": "Swift"
+// CHECK-DAG:     "swift": "SwiftOnoneSupport"
+// CHECK-DAG:     "swift": "_Concurrency"
+// CHECK-DAG:     "clang": "_SwiftConcurrencyShims"
+// CHECK-DAG:     "swift": "_StringProcessing"
+// CHECK: ],
+
+/// --------Swift module F
+// CHECK: "modulePath": "{{.*}}{{/|\\}}F-{{.*}}.swiftmodule",
+// CHECK: directDependencies
+// CHECK-NEXT: {
+// CHECK-DAG:   "clang": "F"
+// CHECK-DAG:   "swift": "Swift"
+// CHECK-DAG:   "swift": "SwiftOnoneSupport"
+
+
+// CHECK: "commandLine": [
+// CHECK-NEXT:            "-frontend",
+// CHECK-NEXT:            "-compile-module-from-interface",
+// CHECK-NEXT:            "-target",
+// ...
+// CHECK:                 "-explicit-interface-module-build",
+// CHECK-NEXT:            "-disable-implicit-swift-modules",
+// CHECK-NEXT:            "-Xcc",
+// CHECK-NEXT:            "-fno-implicit-modules",
+// CHECK-NEXT:            "-Xcc",
+// CHECK-NEXT:            "-fno-implicit-module-maps",
+// CHECK-NEXT:            "-o",
+// CHECK-NEXT:            "{{.*}}{{/|\\}}F-{{.*}}.swiftmodule"
+// CHECK-DAG:             "-swift-module-file=Swift={{.*}}{{/|\\}}Swift-{{.*}}.swiftmodule"
+// CHECK-DAG:             "-swift-module-file=SwiftOnoneSupport={{.*}}{{/|\\}}SwiftOnoneSupport-{{.*}}.swiftmodule"
+// CHECK-DAG:             "-fmodule-file=F={{.*}}{{/|\\}}F-{{.*}}.pcm",
+// CHECK-DAG:             "-fmodule-file=SwiftShims={{.*}}{{/|\\}}SwiftShims-{{.*}}.pcm",
diff --git a/test/ScanDependencies/module_deps_cache_reuse.swift b/test/ScanDependencies/module_deps_cache_reuse.swift
index 41eda3dae6a..d683fb18c24 100644
--- a/test/ScanDependencies/module_deps_cache_reuse.swift
+++ b/test/ScanDependencies/module_deps_cache_reuse.swift
@@ -62,40 +62,24 @@ import SubE
 // CHECK-NEXT: "F"
 // CHECK-NEXT: ]
 
-/// --------Clang module C
-// CHECK-LABEL: "modulePath": "{{.*}}/C-{{.*}}.pcm",
-
-// CHECK: "sourceFiles": [
-// CHECK-DAG: module.modulemap
-// CHECK-DAG: C.h
+/// --------Swift module A
+// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}A-{{.*}}.swiftmodule",
 
 // CHECK: directDependencies
 // CHECK-NEXT: {
-// CHECK-NEXT: "clang": "B"
+// CHECK-DAG:   "clang": "A"
+// CHECK-DAG:   "swift": "Swift"
 
-// CHECK: "moduleMapPath"
-// CHECK-SAME: module.modulemap
-
-// CHECK: "contextHash"
-// CHECK-SAME: "{{.*}}"
-
-// CHECK: "commandLine": [
-// CHECK-NEXT: "-frontend"
-// CHECK-NEXT: "-only-use-extra-clang-opts
-// CHECK-NOT: "BUILD_DIR/bin/clang"
-// CHECK: "-emit-pcm",
-// CHECK: "-module-name",
-// CHECK-NEXT: "C"
-
-/// --------Swift module E
-// CHECK: "swift": "E"
-// CHECK-LABEL: modulePath": "{{.*}}{{/|\\}}E-{{.*}}.swiftmodule"
-// CHECK: "directDependencies"
-// CHECK-NEXT: {
-// CHECK-NEXT: "swift": "Swift"
-
-// CHECK: "moduleInterfacePath"
-// CHECK-SAME: E.swiftinterface
+/// --------Swift module F
+// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}F-{{.*}}.swiftmodule",
+// CHECK-NEXT: "sourceFiles": [
+// CHECK-NEXT: ],
+// CHECK-NEXT: "directDependencies": [
+// CHECK-NEXT:   {
+// CHECK-DAG:     "clang": "F"
+// CHECK-DAG:     "swift": "Swift"
+// CHECK-DAG:     "swift": "SwiftOnoneSupport"
+// CHECK: ],
 
 /// --------Swift module G
 // CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}G-{{.*}}.swiftmodule"
@@ -121,6 +105,16 @@ import SubE
 // CHECK"   "-fapinotes-swift-version=5"
 // CHECK" ]
 
+/// --------Swift module E
+// CHECK: "swift": "E"
+// CHECK-LABEL: modulePath": "{{.*}}{{/|\\}}E-{{.*}}.swiftmodule"
+// CHECK: "directDependencies"
+// CHECK-NEXT: {
+// CHECK-NEXT: "swift": "Swift"
+
+// CHECK: "moduleInterfacePath"
+// CHECK-SAME: E.swiftinterface
+
 /// --------Swift module Swift
 // CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}Swift-{{.*}}.swiftmodule",
 
@@ -128,24 +122,34 @@ import SubE
 // CHECK-NEXT: {
 // CHECK-NEXT: "clang": "SwiftShims"
 
-/// --------Swift module F
-// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}F-{{.*}}.swiftmodule",
-// CHECK-NEXT: "sourceFiles": [
-// CHECK-NEXT: ],
-// CHECK-NEXT: "directDependencies": [
-// CHECK-NEXT:   {
-// CHECK-DAG:     "clang": "F"
-// CHECK-DAG:     "swift": "Swift"
-// CHECK-DAG:     "swift": "SwiftOnoneSupport"
-// CHECK: ],
 
-/// --------Swift module A
-// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}A-{{.*}}.swiftmodule",
+/// --------Clang module SwiftShims
+// CHECK-LABEL: "modulePath": "{{.*}}/SwiftShims-{{.*}}.pcm",
+
+/// --------Clang module C
+// CHECK-LABEL: "modulePath": "{{.*}}/C-{{.*}}.pcm",
+
+// CHECK: "sourceFiles": [
+// CHECK-DAG: module.modulemap
+// CHECK-DAG: C.h
 
 // CHECK: directDependencies
 // CHECK-NEXT: {
-// CHECK-DAG:   "clang": "A"
-// CHECK-DAG:   "swift": "Swift"
+// CHECK-NEXT: "clang": "B"
+
+// CHECK: "moduleMapPath"
+// CHECK-SAME: module.modulemap
+
+// CHECK: "contextHash"
+// CHECK-SAME: "{{.*}}"
+
+// CHECK: "commandLine": [
+// CHECK-NEXT: "-frontend"
+// CHECK-NOT: "BUILD_DIR/bin/clang"
+// CHECK: "-emit-pcm",
+// CHECK: "-module-name",
+// CHECK-NEXT: "C"
+// CHECK-NEXT: "-only-use-extra-clang-opts
 
 /// --------Clang module B
 // CHECK-LABEL: "modulePath": "{{.*}}/B-{{.*}}.pcm",
@@ -158,7 +162,3 @@ import SubE
 // CHECK-NEXT: {
 // CHECK-NEXT: "clang": "A"
 // CHECK-NEXT: }
-
-/// --------Clang module SwiftShims
-// CHECK-LABEL: "modulePath": "{{.*}}/SwiftShims-{{.*}}.pcm",
-
diff --git a/test/ScanDependencies/module_deps_external.swift b/test/ScanDependencies/module_deps_external.swift
index 561dbe30d14..bbf302d94fb 100644
--- a/test/ScanDependencies/module_deps_external.swift
+++ b/test/ScanDependencies/module_deps_external.swift
@@ -71,13 +71,6 @@ import SomeExternalModule
 // CHECK-NEXT: "F"
 // CHECK-NEXT: ]
 
-/// --------Swift external module SomeExternalModule
-// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}SomeExternalModule.swiftmodule",
-// CHECK-NEXT: "details": {
-// CHECK-NEXT: "swiftPlaceholder": {
-// CHECK-NEXT: "moduleDocPath": "BUILD_DIR/{{.*}}/ScanDependencies/Output/module_deps_external.swift.tmp/inputs/SomeExternalModule.swiftdoc",
-// CHECK-NEXT: "moduleSourceInfoPath": "BUILD_DIR/{{.*}}/ScanDependencies/Output/module_deps_external.swift.tmp/inputs/SomeExternalModule.swiftsourceinfo"
-
 /// --------Swift module Swift
 // CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}Swift-{{.*}}.swiftmodule",
 
@@ -93,3 +86,10 @@ import SomeExternalModule
 // CHECK-MAKE-DEPS-SAME: Bridging.h
 // CHECK-MAKE-DEPS-SAME: BridgingOther.h
 // CHECK-MAKE-DEPS-SAME: module.modulemap
+
+/// --------Swift external module SomeExternalModule
+// CHECK-LABEL: "modulePath": "{{.*}}{{/|\\}}SomeExternalModule.swiftmodule",
+// CHECK-NEXT: "details": {
+// CHECK-NEXT: "swiftPlaceholder": {
+// CHECK-NEXT: "moduleDocPath": "BUILD_DIR/{{.*}}/ScanDependencies/Output/module_deps_external.swift.tmp/inputs/SomeExternalModule.swiftdoc",
+// CHECK-NEXT: "moduleSourceInfoPath": "BUILD_DIR/{{.*}}/ScanDependencies/Output/module_deps_external.swift.tmp/inputs/SomeExternalModule.swiftsourceinfo"