Index: llvm/trunk/docs/CommandGuide/FileCheck.rst
===================================================================
--- llvm/trunk/docs/CommandGuide/FileCheck.rst
+++ llvm/trunk/docs/CommandGuide/FileCheck.rst
@@ -24,6 +24,9 @@
 OPTIONS
 -------
 
+Options are parsed from the environment variable ``FILECHECK_OPTS``
+and from the command line.
+
 .. option:: -help
 
  Print a summary of command line options.
Index: llvm/trunk/include/llvm/Support/CommandLine.h
===================================================================
--- llvm/trunk/include/llvm/Support/CommandLine.h
+++ llvm/trunk/include/llvm/Support/CommandLine.h
@@ -56,9 +56,18 @@
 // Returns true on success. Otherwise, this will print the error message to
 // stderr and exit if \p Errs is not set (nullptr by default), or print the
 // error message to \p Errs and return false if \p Errs is provided.
+//
+// If EnvVar is not nullptr, command-line options are also parsed from the
+// environment variable named by EnvVar.  Precedence is given to occurrences
+// from argv.  This precedence is currently implemented by parsing argv after
+// the environment variable, so it is only implemented correctly for options
+// that give precedence to later occurrences.  If your program supports options
+// that give precedence to earlier occurrences, you will need to extend this
+// function to support it correctly.
 bool ParseCommandLineOptions(int argc, const char *const *argv,
                              StringRef Overview = "",
-                             raw_ostream *Errs = nullptr);
+                             raw_ostream *Errs = nullptr,
+                             const char *EnvVar = nullptr);
 
 //===----------------------------------------------------------------------===//
 // ParseEnvironmentOptions - Environment variable option processing alternate
Index: llvm/trunk/lib/Support/CommandLine.cpp
===================================================================
--- llvm/trunk/lib/Support/CommandLine.cpp
+++ llvm/trunk/lib/Support/CommandLine.cpp
@@ -1061,8 +1061,27 @@
 }
 
 bool cl::ParseCommandLineOptions(int argc, const char *const *argv,
-                                 StringRef Overview, raw_ostream *Errs) {
-  return GlobalParser->ParseCommandLineOptions(argc, argv, Overview,
+                                 StringRef Overview, raw_ostream *Errs,
+                                 const char *EnvVar) {
+  SmallVector<const char *, 20> NewArgv;
+  BumpPtrAllocator A;
+  StringSaver Saver(A);
+  NewArgv.push_back(argv[0]);
+
+  // Parse options from environment variable.
+  if (EnvVar) {
+    if (llvm::Optional<std::string> EnvValue =
+            sys::Process::GetEnv(StringRef(EnvVar)))
+      TokenizeGNUCommandLine(*EnvValue, Saver, NewArgv);
+  }
+
+  // Append options from command line.
+  for (int I = 1; I < argc; ++I)
+    NewArgv.push_back(argv[I]);
+  int NewArgc = static_cast<int>(NewArgv.size());
+
+  // Parse all options.
+  return GlobalParser->ParseCommandLineOptions(NewArgc, &NewArgv[0], Overview,
                                                Errs);
 }
 
Index: llvm/trunk/test/FileCheck/envvar-opts.txt
===================================================================
--- llvm/trunk/test/FileCheck/envvar-opts.txt
+++ llvm/trunk/test/FileCheck/envvar-opts.txt
@@ -0,0 +1,15 @@
+; Create a case that produces a simple diagnostic.
+; RUN: echo foo > %t.in
+; CHECK: foo
+; CHECK: bar
+
+; RUN: FILECHECK_OPTS= \
+; RUN: not FileCheck %s -input-file %t.in 2>&1 \
+; RUN: | FileCheck -check-prefix QUIET %s
+
+; RUN: FILECHECK_OPTS=-v \
+; RUN: not FileCheck %s -input-file %t.in 2>&1 \
+; RUN: | FileCheck -check-prefix VERB %s
+
+; QUIET-NOT: remark: {{CHECK}}: expected string found in input
+; VERB:      remark: {{CHECK}}: expected string found in input
Index: llvm/trunk/utils/FileCheck/FileCheck.cpp
===================================================================
--- llvm/trunk/utils/FileCheck/FileCheck.cpp
+++ llvm/trunk/utils/FileCheck/FileCheck.cpp
@@ -114,7 +114,8 @@
   llvm::sys::Process::UseANSIEscapeCodes(true);
 
   InitLLVM X(argc, argv);
-  cl::ParseCommandLineOptions(argc, argv);
+  cl::ParseCommandLineOptions(argc, argv, /*Overview*/ "", /*Errs*/ nullptr,
+                              "FILECHECK_OPTS");
 
   FileCheckRequest Req;
   for (auto Prefix : CheckPrefixes)
Index: llvm/trunk/utils/lit/lit/TestingConfig.py
===================================================================
--- llvm/trunk/utils/lit/lit/TestingConfig.py
+++ llvm/trunk/utils/lit/lit/TestingConfig.py
@@ -26,7 +26,7 @@
                      'LSAN_OPTIONS', 'ADB', 'ANDROID_SERIAL',
                      'SANITIZER_IGNORE_CVE_2016_2143', 'TMPDIR', 'TMP', 'TEMP',
                      'TEMPDIR', 'AVRLIT_BOARD', 'AVRLIT_PORT',
-                     'FILECHECK_DUMP_INPUT_ON_FAILURE']
+                     'FILECHECK_DUMP_INPUT_ON_FAILURE', 'FILECHECK_OPTS']
         for var in pass_vars:
             val = os.environ.get(var, '')
             # Check for empty string as some variables such as LD_PRELOAD cannot be empty