Index: lld/ELF/Config.h
===================================================================
--- lld/ELF/Config.h
+++ lld/ELF/Config.h
@@ -11,6 +11,7 @@
 
 #include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/BinaryFormat/ELF.h"
@@ -90,11 +91,13 @@
   uint8_t osabi = 0;
   uint32_t andFeatures = 0;
   llvm::CachePruningPolicy thinLTOCachePolicy;
+  llvm::SetVector<StringRef> dependencyFiles; // for --dependency-file
   llvm::StringMap<uint64_t> sectionStartMap;
   llvm::StringRef bfdname;
   llvm::StringRef chroot;
-  llvm::StringRef dynamicLinker;
+  llvm::StringRef dependencyFile;
   llvm::StringRef dwoDir;
+  llvm::StringRef dynamicLinker;
   llvm::StringRef entry;
   llvm::StringRef emulation;
   llvm::StringRef fini;
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -916,6 +916,7 @@
   config->optimizeBBJumps =
       args.hasFlag(OPT_optimize_bb_jumps, OPT_no_optimize_bb_jumps, false);
   config->demangle = args.hasFlag(OPT_demangle, OPT_no_demangle, true);
+  config->dependencyFile = args.getLastArgValue(OPT_dependency_file);
   config->dependentLibraries = args.hasFlag(OPT_dependent_libraries, OPT_no_dependent_libraries, true);
   config->disableVerify = args.hasArg(OPT_disable_verify);
   config->discard = getDiscard(args);
@@ -1541,6 +1542,75 @@
     sym->fetch();
 }
 
+// Handle --dependency-file=<path>. If that option is given, lld creates a
+// file at a given path with the following contents:
+//
+//   <output-file>: <input-file> ...
+//
+//   <input-file>:
+//
+// where <output-file> is a pathname of an output file and <input-file>
+// ... is a list of pathnames of all input files. `make` command can read a
+// file in the above format and interpret it as a dependency info. We write
+// phony targets for every <input-file> to avoid an error when that file is
+// removed.
+//
+// This option is useful if you want to make your final executable to depend
+// on all input files including system libraries. Here is why.
+//
+// When you write a Makefile, you usually write it so that the final
+// executable depends on all user-generated object files. Normally, you
+// don't make your executable to depend on system libraries (such as libc)
+// because you don't know the exact paths of libraries, even though system
+// libraries that are linked to your executable statically are technically a
+// part of your program. By using --dependency-file option, you can make
+// lld to dump dependency info so that you can maintain exact dependencies
+// easily.
+static void writeDependencyFile() {
+  std::error_code ec;
+  raw_fd_ostream os(config->dependencyFile, ec, sys::fs::F_None);
+  if (ec) {
+    error("cannot open " + config->dependencyFile + ": " + ec.message());
+    return;
+  }
+
+  // We use the same escape rules as Clang/GCC which are accepted by Make/Ninja:
+  // * A space is escaped by a backslash which itself must be escaped.
+  // * A hash sign is escaped by a single backslash.
+  // * $ is escapes as $$.
+  auto printFilename = [](raw_fd_ostream &os, StringRef filename) {
+    llvm::SmallString<256> nativePath;
+    llvm::sys::path::native(filename.str(), nativePath);
+    llvm::sys::path::remove_dots(nativePath, /*remove_dot_dot=*/true);
+    for (unsigned i = 0, e = nativePath.size(); i != e; ++i) {
+      if (nativePath[i] == '#') {
+        os << '\\';
+      } else if (nativePath[i] == ' ') {
+        os << '\\';
+        unsigned j = i;
+        while (j > 0 && nativePath[--j] == '\\')
+          os << '\\';
+      } else if (nativePath[i] == '$') {
+        os << '$';
+      }
+      os << nativePath[i];
+    }
+  };
+
+  os << config->outputFile << ":";
+  for (StringRef path : config->dependencyFiles) {
+    os << " \\\n ";
+    printFilename(os, path);
+  }
+  os << "\n";
+
+  for (StringRef path : config->dependencyFiles) {
+    os << "\n";
+    printFilename(os, path);
+    os << ":\n";
+  }
+}
+
 // Replaces common symbols with defined symbols reside in .bss sections.
 // This function is called after all symbol names are resolved. As a
 // result, the passes after the symbol resolution won't see any
@@ -2038,6 +2108,11 @@
     return false;
   });
 
+  // Since we now have a complete set of input files, we can create
+  // a .d file to record build dependencies.
+  if (!config->dependencyFile.empty())
+    writeDependencyFile();
+
   // Now that the number of partitions is fixed, save a pointer to the main
   // partition.
   mainPart = &partitions[0];
Index: lld/ELF/InputFiles.cpp
===================================================================
--- lld/ELF/InputFiles.cpp
+++ lld/ELF/InputFiles.cpp
@@ -110,6 +110,7 @@
     path = saver.save(config->chroot + path);
 
   log(path);
+  config->dependencyFiles.insert(path);
 
   auto mbOrErr = MemoryBuffer::getFile(path, -1, false);
   if (auto ec = mbOrErr.getError()) {
Index: lld/ELF/Options.td
===================================================================
--- lld/ELF/Options.td
+++ lld/ELF/Options.td
@@ -132,6 +132,9 @@
     "Demangle symbol names (default)",
     "Do not demangle symbol names">;
 
+defm dependency_file: Eq<"dependency-file", "Write a dependency file">,
+  MetaVarName<"<path>">;
+
 def disable_new_dtags: F<"disable-new-dtags">,
   HelpText<"Disable new dynamic tags">;