Index: llvm/test/tools/dsymutil/X86/swift-ast-x86_64.test
===================================================================
--- llvm/test/tools/dsymutil/X86/swift-ast-x86_64.test
+++ llvm/test/tools/dsymutil/X86/swift-ast-x86_64.test
@@ -20,7 +20,7 @@
 DWARFDUMP: __swift_ast
 
 RUN: dsymutil -oso-prepend-path %p/.. %p/../Inputs/swift-ast.macho.x86_64 -no-output -verbose 2>&1 | FileCheck %s --check-prefix=TIMESTAMP
-TIMESTAMP: warning: Timestamp mismatch
+TIMESTAMP: warning: {{.*}}/swift-ast.swiftmodule: timestamp mismatch between swift interface file ({{.*}}) and debug map ({{.*}})
 
 RUN: dsymutil -s %T/swift-ast.dSYM/Contents/Resources/DWARF/swift-ast.macho.x86_64 | FileCheck %s --check-prefix=NAST
 NAST-NOT: N_AST
Index: llvm/test/tools/dsymutil/debug-map-parsing.test
===================================================================
--- llvm/test/tools/dsymutil/debug-map-parsing.test
+++ llvm/test/tools/dsymutil/debug-map-parsing.test
@@ -1,3 +1,4 @@
+RUN: touch %p/Inputs/basic.macho.x86_64.o
 RUN: dsymutil -dump-debug-map -oso-prepend-path=%p %p/Inputs/basic.macho.x86_64 | FileCheck %s
 RUN: dsymutil -dump-debug-map -oso-prepend-path=%p %p/Inputs/basic-lto.macho.x86_64 | FileCheck %s --check-prefix=CHECK-LTO
 RUN: dsymutil -verbose -dump-debug-map -oso-prepend-path=%p %p/Inputs/basic-archive.macho.x86_64 2>&1 | FileCheck %s --check-prefix=CHECK-ARCHIVE
@@ -46,6 +47,7 @@
 CHECK-ARCHIVE:      trying to open {{.*}}basic-archive.macho.x86_64'
 CHECK-ARCHIVE-NEXT: 	loaded object.
 CHECK-ARCHIVE-NEXT: trying to open {{.*}}/Inputs/basic1.macho.x86_64.o'
+CHECK-ARCHIVE-NEXT: warning: {{.*}}/Inputs/basic1.macho.x86_64.o: timestamp mismatch between object file ({{.*}}) and debug map ({{.*}})
 CHECK-ARCHIVE-NEXT: 	loaded object.
 CHECK-ARCHIVE-NEXT: trying to open {{.*}}/libbasic.a(basic2.macho.x86_64.o)'
 CHECK-ARCHIVE-NEXT: 	loaded archive {{.*}}/libbasic.a'
Index: llvm/tools/dsymutil/BinaryHolder.h
===================================================================
--- llvm/tools/dsymutil/BinaryHolder.h
+++ llvm/tools/dsymutil/BinaryHolder.h
@@ -58,7 +58,7 @@
   public:
     /// Load the given object binary in memory.
     Error load(IntrusiveRefCntPtr<vfs::FileSystem> VFS, StringRef Filename,
-               bool Verbose = false);
+               TimestampTy Timestamp, bool Verbose = false);
 
     /// Access all owned ObjectFiles.
     std::vector<const object::ObjectFile *> getObjects() const;
Index: llvm/tools/dsymutil/BinaryHolder.cpp
===================================================================
--- llvm/tools/dsymutil/BinaryHolder.cpp
+++ llvm/tools/dsymutil/BinaryHolder.cpp
@@ -87,7 +87,8 @@
 }
 
 Error BinaryHolder::ObjectEntry::load(IntrusiveRefCntPtr<vfs::FileSystem> VFS,
-                                      StringRef Filename, bool Verbose) {
+                                      StringRef Filename, TimestampTy Timestamp,
+                                      bool Verbose) {
   // Try to load regular binary and force it to be memory mapped.
   auto ErrOrBuff = (Filename == "-")
                        ? MemoryBuffer::getSTDIN()
@@ -95,6 +96,17 @@
   if (auto Err = ErrOrBuff.getError())
     return errorCodeToError(Err);
 
+  if (Filename != "-" && Timestamp != sys::TimePoint<>()) {
+    llvm::ErrorOr<vfs::Status> Stat = VFS->status(Filename);
+    if (!Stat)
+      return errorCodeToError(Stat.getError());
+    if (Timestamp != Stat->getLastModificationTime())
+      WithColor::warning() << Filename
+                           << ": timestamp mismatch between object file ("
+                           << Stat->getLastModificationTime()
+                           << ") and debug map (" << Timestamp << ")\n";
+  }
+
   MemBuffer = std::move(*ErrOrBuff);
 
   if (Verbose)
@@ -182,7 +194,11 @@
           if (Timestamp != sys::TimePoint<>() &&
               Timestamp != ModTimeOrErr.get()) {
             if (Verbose)
-              WithColor::warning() << "member has timestamp mismatch.\n";
+              WithColor::warning()
+                  << *NameOrErr
+                  << ": timestamp mismatch between archive member ("
+                  << ModTimeOrErr.get() << ") and debug map (" << Timestamp
+                  << ")\n";
             continue;
           }
 
@@ -246,7 +262,7 @@
   std::lock_guard<std::mutex> Lock(ObjectCacheMutex);
   if (!ObjectCache.count(Filename)) {
     ObjectEntry &OE = ObjectCache[Filename];
-    auto Err = OE.load(VFS, Filename, Verbose);
+    auto Err = OE.load(VFS, Filename, Timestamp, Verbose);
     if (Err) {
       ObjectCache.erase(Filename);
       return std::move(Err);
Index: llvm/tools/dsymutil/DwarfLinkerForBinary.cpp
===================================================================
--- llvm/tools/dsymutil/DwarfLinkerForBinary.cpp
+++ llvm/tools/dsymutil/DwarfLinkerForBinary.cpp
@@ -412,9 +412,10 @@
                 Stat.getLastModificationTime());
         if (ModificationTime != Obj->getTimestamp()) {
           // Not using the helper here as we can easily stream TimePoint<>.
-          WithColor::warning() << "Timestamp mismatch for " << File << ": "
-                               << Stat.getLastModificationTime() << " and "
-                               << sys::TimePoint<>(Obj->getTimestamp()) << "\n";
+          WithColor::warning()
+              << File << ": timestamp mismatch between swift interface file ("
+              << sys::TimePoint<>(Obj->getTimestamp()) << ") and debug map ("
+              << sys::TimePoint<>(Obj->getTimestamp()) << ")\n";
           continue;
         }
       }