diff --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -102,6 +102,7 @@
     CI.getCodeGenOpts().CoverageCompilationDir.clear();
     CI.getCodeGenOpts().CoverageDataFile.clear();
     CI.getCodeGenOpts().CoverageNotesFile.clear();
+    CI.getCodeGenOpts().RelaxAll = false;
   }
 
   // Map output paths that affect behaviour to "-" so their existence is in the
diff --git a/clang/test/ClangScanDeps/shared-module-for-tu-and-pch.c b/clang/test/ClangScanDeps/shared-module-for-tu-and-pch.c
new file mode 100644
--- /dev/null
+++ b/clang/test/ClangScanDeps/shared-module-for-tu-and-pch.c
@@ -0,0 +1,42 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+// RUN: sed "s|DIR|%/t|g" %t/cdb.json.debug.template > %t/cdb.debug.json
+// RUN: sed "s|DIR|%/t|g" %t/cdb.json.release.template > %t/cdb.release.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb.debug.json -format=experimental-full -brief | FileCheck %s
+// RUN: clang-scan-deps -compilation-database %t/cdb.release.json -format=experimental-full -brief | FileCheck %s
+// CHECK: num modules: 1
+
+//--- cdb.json.debug.template
+[{
+  "directory": "DIR",
+  "file": "DIR/tu.c",
+  "command": "clang -target x86_64-apple-macosx12 -x c -fmodules -gmodules -fmodules-cache-path=DIR/cache -I DIR/include -c DIR/tu.c -o DIR/tu.o -O0 -g"
+},
+{
+  "directory": "DIR",
+  "file": "DIR/tu.prefix.h",
+  "command": "clang -target x86_64-apple-macosx12 -x c-header -fmodules -gmodules -fmodules-cache-path=DIR/cache -I DIR/include -c DIR/tu.prefix.h -o DIR/tu.pch -O0 -g"
+}]
+//--- cdb.json.release.template
+[{
+  "directory": "DIR",
+  "file": "DIR/tu.c",
+  "command": "clang -target x86_64-apple-macosx12 -x c -fmodules -gmodules -fmodules-cache-path=DIR/cache -I DIR/include -c DIR/tu.c -o DIR/tu.o -Os -g"
+},
+{
+  "directory": "DIR",
+  "file": "DIR/tu.prefix.h",
+  "command": "clang -target x86_64-apple-macosx12 -x c-header -fmodules -gmodules -fmodules-cache-path=DIR/cache -I DIR/include -c DIR/tu.prefix.h -o DIR/tu.pch -Os -g"
+}]
+
+//--- include/module.modulemap
+module Top { header "top.h" }
+//--- include/top.h
+#define TOP int
+//--- tu.c
+#include "top.h"
+TOP fn(void);
+//--- tu.prefix.h
+#include "top.h"
diff --git a/clang/tools/clang-scan-deps/ClangScanDeps.cpp b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
--- a/clang/tools/clang-scan-deps/ClangScanDeps.cpp
+++ b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
@@ -90,6 +90,7 @@
 static bool DeprecatedDriverCommand;
 static ResourceDirRecipeKind ResourceDirRecipe;
 static bool Verbose;
+static bool BriefResult;
 static std::vector<const char *> CommandLine;
 
 #ifndef NDEBUG
@@ -201,6 +202,7 @@
   }
 
   Verbose = Args.hasArg(OPT_verbose);
+  BriefResult = Args.hasArg(OPT_brief_result);
 
   RoundTripArgs = Args.hasArg(OPT_round_trip_args);
 
@@ -462,6 +464,8 @@
     OS << llvm::formatv("{0:2}\n", Value(std::move(Output)));
   }
 
+  size_t getNumModules() const { return Modules.size(); }
+
 private:
   struct IndexedModuleID {
     ModuleID ID;
@@ -950,6 +954,11 @@
     if (FD && FD->roundTripCommands(llvm::errs()))
       HadErrors = true;
 
+  if (BriefResult && FD) {
+    llvm::outs() << "num modules: " << FD->getNumModules() << '\n';
+    return HadErrors;
+  }
+
   if (Format == ScanningOutputFormat::Full)
     FD->printFullOutput(llvm::outs());
   else if (Format == ScanningOutputFormat::P1689)
diff --git a/clang/tools/clang-scan-deps/Opts.td b/clang/tools/clang-scan-deps/Opts.td
--- a/clang/tools/clang-scan-deps/Opts.td
+++ b/clang/tools/clang-scan-deps/Opts.td
@@ -33,6 +33,8 @@
 
 def verbose : F<"v", "Use verbose output">;
 
+def brief_result : F<"brief", "Use brief dependency info output">;
+
 def round_trip_args : F<"round-trip-args", "verify that command-line arguments are canonical by parsing and re-serializing">;
 
 def DASH_DASH : Option<["--"], "", KIND_REMAINING_ARGS>;
\ No newline at end of file