Index: lld/MachO/Config.h
===================================================================
--- lld/MachO/Config.h
+++ lld/MachO/Config.h
@@ -133,6 +133,8 @@
   SymbolPatterns exportedSymbols;
   SymbolPatterns unexportedSymbols;
 
+  bool writeModTimeToDebugInfo = true;
+
   llvm::MachO::Architecture arch() const { return platformInfo.target.Arch; }
 
   llvm::MachO::PlatformKind platform() const {
Index: lld/MachO/Driver.cpp
===================================================================
--- lld/MachO/Driver.cpp
+++ lld/MachO/Driver.cpp
@@ -986,6 +986,9 @@
   config->emitFunctionStarts = !args.hasArg(OPT_no_function_starts);
   config->emitBitcodeBundle = args.hasArg(OPT_bitcode_bundle);
 
+  // FIXME: Add a commandline flag for this too.
+  config->writeModTimeToDebugInfo = !getenv("ZERO_AR_DATE");
+
   std::array<PlatformKind, 3> encryptablePlatforms{
       PlatformKind::iOS, PlatformKind::watchOS, PlatformKind::tvOS};
   config->emitEncryptionInfo =
Index: lld/MachO/DriverUtils.cpp
===================================================================
--- lld/MachO/DriverUtils.cpp
+++ lld/MachO/DriverUtils.cpp
@@ -280,6 +280,9 @@
 }
 
 uint32_t macho::getModTime(StringRef path) {
+  if (!config->writeModTimeToDebugInfo)
+    return 0;
+
   fs::file_status stat;
   if (!fs::status(path, stat))
     if (fs::exists(stat))
Index: lld/test/MachO/stabs.s
===================================================================
--- lld/test/MachO/stabs.s
+++ lld/test/MachO/stabs.s
@@ -11,23 +11,34 @@
 
 # RUN: %lld -lSystem %t/test.o %t/foo.o %t/no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 ## Check that we emit the right modtime even when the object file is in an
 ## archive.
 # RUN: %lld -lSystem %t/test.o %t/foo.a %t/no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\)
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\) \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
+
+## Check that we don't emit modtimes if ZERO_AR_DATE is set.
+# RUN: env ZERO_AR_DATE=1 %lld -lSystem %t/test.o %t/foo.o %t/no-debug.o \
+# RUN:     -o %t/test
+# RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000000 -DFOO_TIME=0000000000000000
 
 ## Check that we emit absolute paths to the object files in our OSO entries
 ## even if our inputs are relative paths.
 # RUN: cd %t && %lld -lSystem test.o foo.o no-debug.o -o test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 # RUN: cd %t && %lld -lSystem test.o foo.a no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\)
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\) \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 # CHECK:       Sections:
 # CHECK-NEXT:  Idx                Name
@@ -38,7 +49,7 @@
 # CHECK-NEXT:  [[#MORE_TEXT_ID:]] more_text
 
 # CHECK:      (N_SO         ) 00                         0000   0000000000000000   '/tmp/test.cpp'
-# CHECK-NEXT: (N_OSO        ) 03                         0001   0000000000000010   '[[DIR]]/test.o'
+# CHECK-NEXT: (N_OSO        ) 03                         0001   [[TEST_TIME]]      '[[DIR]]/test.o'
 # CHECK-NEXT: (N_STSYM      ) [[#%.2d,MORE_DATA_ID + 1]] 0000   [[#%.16x,STATIC:]] '_static_var'
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,MAIN:]]   '_main'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000006{{$}}
@@ -60,7 +71,7 @@
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000001{{$}}
 # CHECK-NEXT: (N_SO         ) 01                         0000   0000000000000000{{$}}
 # CHECK-NEXT: (N_SO         ) 00                         0000   0000000000000000   '/foo.cpp'
-# CHECK-NEXT: (N_OSO        ) 03                         0001   0000000000000020   '[[FOO_PATH]]'
+# CHECK-NEXT: (N_OSO        ) 03                         0001   [[FOO_TIME]]       '[[FOO_PATH]]'
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,FOO:]]    '_foo'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000001{{$}}
 # CHECK-NEXT: (N_SO         ) 01                         0000   0000000000000000{{$}}