diff --git a/llvm/docs/CommandGuide/llvm-libtool-darwin.rst b/llvm/docs/CommandGuide/llvm-libtool-darwin.rst
--- a/llvm/docs/CommandGuide/llvm-libtool-darwin.rst
+++ b/llvm/docs/CommandGuide/llvm-libtool-darwin.rst
@@ -38,6 +38,14 @@
 
   Display the version of this program.
 
+.. option:: -D
+
+ Use zero for timestamps and UIDs/GIDs. This is set by default.
+
+.. option:: -U
+
+ Use actual timestamps and UIDs/GIDs.
+
 .. option:: -o <filename>
 
   Specify the output file name. Must be specified exactly once.
diff --git a/llvm/test/tools/llvm-libtool-darwin/deterministic-library.test b/llvm/test/tools/llvm-libtool-darwin/deterministic-library.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-libtool-darwin/deterministic-library.test
@@ -0,0 +1,42 @@
+## This test checks that timestamps/etc. are set to 0 by default or when -D
+## option is specified. Timestamps/etc. are preserved when -U option is
+## specified.
+## We only test timestamps as a proxy for full deterministic writing; i.e. we
+## assume UID/GIDs are preserved if timestamps are preserved.
+
+# RUN: yaml2obj %S/Inputs/input1.yaml -o %t-input1.o
+# RUN: touch -t 199505050555.55 %t-input1.o
+
+## Test values are set to 0 (by default):
+# RUN: llvm-libtool-darwin -static -o %t.lib %t-input1.o
+# RUN: env TZ=GMT llvm-ar tv %t.lib | FileCheck %s --check-prefix=CHECK-DETERMINISTIC
+
+## Test values are set to 0 (with -D):
+# RUN: llvm-libtool-darwin -static -o %t.lib -D %t-input1.o
+# RUN: env TZ=GMT llvm-ar tv %t.lib | FileCheck %s --check-prefix=CHECK-DETERMINISTIC
+
+# CHECK-DETERMINISTIC: {{[[:space:]]1970[[:space:]]}}
+
+## Test values are preserved (with -U):
+# RUN: llvm-libtool-darwin -static -o %t.lib -U %t-input1.o
+# RUN: env TZ=GMT llvm-ar tv %t.lib | FileCheck %s --check-prefix=CHECK-NONDETERMINISTIC
+
+# CHECK-NONDETERMINISTIC:  {{[[:space:]]1995[[:space:]]}}
+
+## D Flag specified more than once:
+# RUN: not llvm-libtool-darwin -static -o %t.lib %t-input1.o -D -D 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=CHECK-ERROR-D
+
+# CHECK-ERROR-D: for the -D option: may only occur zero or one times!
+
+## U Flag specified more than once:
+# RUN: not llvm-libtool-darwin -static -o %t.lib %t-input1.o -U -U 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=CHECK-ERROR-U
+
+# CHECK-ERROR-U: for the -U option: may only occur zero or one times!
+
+## Both D and U flags specified:
+# RUN: not llvm-libtool-darwin -static -o %t.lib %t-input1.o -D -U 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=CHECK-ERROR-BOTH
+
+# CHECK-ERROR-BOTH: error: cannot specify both -D and -U flags
diff --git a/llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp b/llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp
--- a/llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp
+++ b/llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp
@@ -22,6 +22,8 @@
 using namespace llvm;
 using namespace llvm::object;
 
+static bool Deterministic; // Updated by 'D' and 'U' modifiers
+
 cl::OptionCategory LibtoolCategory("llvm-libtool-darwin Options");
 
 static cl::opt<std::string> OutputFile("o", cl::desc("Specify output filename"),
@@ -42,6 +44,14 @@
                    "Produce a statically linked library from the input files")),
     cl::Required, cl::cat(LibtoolCategory));
 
+static cl::opt<bool> DeterministicOption(
+    "D", cl::desc("Use zero for timestamps and UIDs/GIDs (Default)"),
+    cl::init(false), cl::cat(LibtoolCategory));
+
+static cl::opt<bool>
+    NonDeterministicOption("U", cl::desc("Use actual timestamps and UIDs/GIDs"),
+                           cl::init(false), cl::cat(LibtoolCategory));
+
 static cl::opt<std::string>
     FileList("filelist",
              cl::desc("Pass in file containing a list of filenames"),
@@ -101,7 +111,7 @@
 static Error addChildMember(std::vector<NewArchiveMember> &Members,
                             const object::Archive::Child &M) {
   Expected<NewArchiveMember> NMOrErr =
-      NewArchiveMember::getOldMember(M, /*Deterministic=*/true);
+      NewArchiveMember::getOldMember(M, Deterministic);
   if (!NMOrErr)
     return NMOrErr.takeError();
 
@@ -117,7 +127,7 @@
 addMember(std::vector<NewArchiveMember> &Members, StringRef FileName,
           std::vector<std::unique_ptr<MemoryBuffer>> &ArchiveBuffers) {
   Expected<NewArchiveMember> NMOrErr =
-      NewArchiveMember::getFile(FileName, /*Deterministic=*/true);
+      NewArchiveMember::getFile(FileName, Deterministic);
   if (!NMOrErr)
     return createFileError(FileName, NMOrErr.takeError());
 
@@ -163,27 +173,35 @@
 
   if (Error E = writeArchive(OutputFile, NewMembers,
                              /*WriteSymtab=*/true,
-                             /*Kind=*/object::Archive::K_DARWIN,
-                             /*Deterministic=*/true,
+                             /*Kind=*/object::Archive::K_DARWIN, Deterministic,
                              /*Thin=*/false))
     return E;
   return Error::success();
 }
 
+static Error checkCommandLineOptions() {
+  if (DeterministicOption && NonDeterministicOption)
+    return createStringError(std::errc::invalid_argument,
+                             "cannot specify both -D and -U flags");
+  else
+    Deterministic = NonDeterministicOption ? false : true;
+
+  if (!FileList.empty())
+    if (Error E = processFileList())
+      return E;
+
+  if (InputFiles.empty())
+    return createStringError(std::errc::invalid_argument,
+                             "no input files specified");
+
+  return Error::success();
+}
+
 int main(int Argc, char **Argv) {
   InitLLVM X(Argc, Argv);
   cl::HideUnrelatedOptions({&LibtoolCategory, &ColorCategory});
   cl::ParseCommandLineOptions(Argc, Argv, "llvm-libtool-darwin\n");
-  if (!FileList.empty()) {
-    if (Error E = processFileList()) {
-      WithColor::defaultErrorHandler(std::move(E));
-      return EXIT_FAILURE;
-    }
-  }
-
-  if (InputFiles.empty()) {
-    Error E = createStringError(std::errc::invalid_argument,
-                                "no input files specified");
+  if (Error E = checkCommandLineOptions()) {
     WithColor::defaultErrorHandler(std::move(E));
     return EXIT_FAILURE;
   }