Index: llvm/lib/Support/CommandLine.cpp
===================================================================
--- llvm/lib/Support/CommandLine.cpp
+++ llvm/lib/Support/CommandLine.cpp
@@ -1097,43 +1097,73 @@
 bool cl::ExpandResponseFiles(StringSaver &Saver, TokenizerCallback Tokenizer,
                              SmallVectorImpl<const char *> &Argv,
                              bool MarkEOLs, bool RelativeNames) {
-  unsigned ExpandedRspFiles = 0;
   bool AllExpanded = true;
+  struct ResponseFileRecord {
+    const char *File;
+    size_t End;
+  };
+
+  SmallVector<ResponseFileRecord, 3> FileStack;
+
+  // Push a dummy entry that represents the initial command line, removing
+  // the need to check for an empty list.
+  FileStack.push_back({"", Argv.size()});
 
   // Don't cache Argv.size() because it can change.
   for (unsigned I = 0; I != Argv.size();) {
+    while (I == FileStack.back().End) {
+      FileStack.pop_back();
+    }
+
     const char *Arg = Argv[I];
     // Check if it is an EOL marker
     if (Arg == nullptr) {
       ++I;
       continue;
     }
+
     if (Arg[0] != '@') {
       ++I;
       continue;
     }
 
-    // If we have too many response files, leave some unexpanded.  This avoids
-    // crashing on self-referential response files.
-    if (ExpandedRspFiles > 20)
-      return false;
+    const char *FName = Arg + 1;
+    auto IsEquivalent = [FName](const ResponseFileRecord &RFile) {
+      return sys::fs::equivalent(RFile.File, FName);
+    };
+
+    // Check for recursize response files.
+    if (std::any_of(FileStack.begin()+1, FileStack.end(), IsEquivalent)) {
+      // This file is recursive, so we leave it in the argument stream and
+      // move on.
+      AllExpanded = false;
+      ++I;
+      continue;
+    }
 
     // Replace this response file argument with the tokenization of its
     // contents.  Nested response files are expanded in subsequent iterations.
     SmallVector<const char *, 0> ExpandedArgv;
-    if (ExpandResponseFile(Arg + 1, Saver, Tokenizer, ExpandedArgv, MarkEOLs,
-                           RelativeNames)) {
-      ++ExpandedRspFiles;
-    } else {
+    if (!ExpandResponseFile(FName, Saver, Tokenizer, ExpandedArgv, MarkEOLs,
+                            RelativeNames)) {
       // We couldn't read this file, so we leave it in the argument stream and
       // move on.
       AllExpanded = false;
       ++I;
       continue;
     }
+
+    for (ResponseFileRecord &Record : FileStack) {
+      // All records are now bigger. Don't include the @resp file itself, so -1
+      Record.End += ExpandedArgv.size() - 1;
+    }
+
+    FileStack.push_back({FName, I + ExpandedArgv.size()});
     Argv.erase(Argv.begin() + I);
     Argv.insert(Argv.begin() + I, ExpandedArgv.begin(), ExpandedArgv.end());
   }
+
+  assert(Argv.size() == FileStack.back().End);
   return AllExpanded;
 }
 
Index: llvm/unittests/Support/CommandLineTest.cpp
===================================================================
--- llvm/unittests/Support/CommandLineTest.cpp
+++ llvm/unittests/Support/CommandLineTest.cpp
@@ -790,7 +790,9 @@
   EXPECT_TRUE(IncludedFile.is_open());
   IncludedFile << "-option_1 -option_2\n"
                   "@incdir/resp2\n"
-                  "-option_3=abcd\n";
+                  "-option_3=abcd\n"
+                  "@incdir/resp3\n"
+                  "-option_4=efjk\n";
   IncludedFile.close();
 
   // Directory for included file.
@@ -808,6 +810,15 @@
   IncludedFile2 << "-option_23=abcd\n";
   IncludedFile2.close();
 
+  // Create second included response file of second level.
+  llvm::SmallString<128> IncludedFileName3;
+  llvm::sys::path::append(IncludedFileName3, IncDir, "resp3");
+  std::ofstream IncludedFile3(IncludedFileName3.c_str());
+  EXPECT_TRUE(IncludedFile3.is_open());
+  IncludedFile3 << "-option_31 -option_32\n";
+  IncludedFile3 << "-option_33=abcd\n";
+  IncludedFile3.close();
+
   // Prepare 'file' with reference to response file.
   SmallString<128> IncRef;
   IncRef.append(1, '@');
@@ -821,7 +832,7 @@
   bool Res = llvm::cl::ExpandResponseFiles(
                     Saver, llvm::cl::TokenizeGNUCommandLine, Argv, false, true);
   EXPECT_TRUE(Res);
-  EXPECT_EQ(Argv.size(), 9U);
+  EXPECT_EQ(Argv.size(), 13U);
   EXPECT_STREQ(Argv[0], "test/test");
   EXPECT_STREQ(Argv[1], "-flag_1");
   EXPECT_STREQ(Argv[2], "-option_1");
@@ -830,8 +841,13 @@
   EXPECT_STREQ(Argv[5], "-option_22");
   EXPECT_STREQ(Argv[6], "-option_23=abcd");
   EXPECT_STREQ(Argv[7], "-option_3=abcd");
-  EXPECT_STREQ(Argv[8], "-flag_2");
+  EXPECT_STREQ(Argv[8], "-option_31");
+  EXPECT_STREQ(Argv[9], "-option_32");
+  EXPECT_STREQ(Argv[10], "-option_33=abcd");
+  EXPECT_STREQ(Argv[11], "-option_4=efjk");
+  EXPECT_STREQ(Argv[12], "-flag_2");
 
+  llvm::sys::fs::remove(IncludedFileName3);
   llvm::sys::fs::remove(IncludedFileName2);
   llvm::sys::fs::remove(IncDir);
   llvm::sys::fs::remove(IncludedFileName);