diff --git a/clang/include/clang/Tooling/CompilationDatabase.h b/clang/include/clang/Tooling/CompilationDatabase.h
--- a/clang/include/clang/Tooling/CompilationDatabase.h
+++ b/clang/include/clang/Tooling/CompilationDatabase.h
@@ -184,11 +184,16 @@
       int &Argc, const char *const *Argv, std::string &ErrorMsg,
       Twine Directory = ".");
 
-  /// Reads flags from the given file, one-per line.
+  /// Reads flags from the given file, one-per-line.
   /// Returns nullptr and sets ErrorMessage if we can't read the file.
   static std::unique_ptr<FixedCompilationDatabase>
   loadFromFile(StringRef Path, std::string &ErrorMsg);
 
+  /// Reads flags from the given buffer, one-per-line.
+  /// Directory is the command CWD, typically the parent of compile_flags.txt.
+  static std::unique_ptr<FixedCompilationDatabase>
+  loadFromBuffer(StringRef Directory, StringRef Data, std::string &ErrorMsg);
+
   /// Constructs a compilation data base from a specified directory
   /// and command line.
   FixedCompilationDatabase(Twine Directory, ArrayRef<std::string> CommandLine);
diff --git a/clang/lib/Tooling/CompilationDatabase.cpp b/clang/lib/Tooling/CompilationDatabase.cpp
--- a/clang/lib/Tooling/CompilationDatabase.cpp
+++ b/clang/lib/Tooling/CompilationDatabase.cpp
@@ -348,16 +348,24 @@
     ErrorMsg = "Error while opening fixed database: " + Result.message();
     return nullptr;
   }
+  return loadFromBuffer(llvm::sys::path::parent_path(Path),
+                        (*File)->getBuffer(), ErrorMsg);
+}
+
+std::unique_ptr<FixedCompilationDatabase>
+FixedCompilationDatabase::loadFromBuffer(StringRef Directory, StringRef Data,
+                                         std::string &ErrorMsg) {
+  ErrorMsg.clear();
   std::vector<std::string> Args;
-  for (llvm::StringRef Line :
-       llvm::make_range(llvm::line_iterator(**File), llvm::line_iterator())) {
+  StringRef Line;
+  while (!Data.empty()) {
+    std::tie(Line, Data) = Data.split('\n');
     // Stray whitespace is almost certainly unintended.
     Line = Line.trim();
     if (!Line.empty())
       Args.push_back(Line.str());
   }
-  return std::make_unique<FixedCompilationDatabase>(
-      llvm::sys::path::parent_path(Path), std::move(Args));
+  return std::make_unique<FixedCompilationDatabase>(Directory, std::move(Args));
 }
 
 FixedCompilationDatabase::
diff --git a/clang/unittests/Tooling/CompilationDatabaseTest.cpp b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
--- a/clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -543,6 +543,27 @@
   EXPECT_EQ(0ul, Database.getAllCompileCommands().size());
 }
 
+TEST(FixedCompilationDatabase, FromBuffer) {
+  const char *Data = R"(
+
+ -DFOO=BAR
+
+--baz
+
+  )";
+  std::string ErrorMsg;
+  auto CDB =
+      FixedCompilationDatabase::loadFromBuffer("/cdb/dir", Data, ErrorMsg);
+
+  std::vector<CompileCommand> Result = CDB->getCompileCommands("/foo/bar.cc");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_EQ("/cdb/dir", Result.front().Directory);
+  EXPECT_EQ("/foo/bar.cc", Result.front().Filename);
+  EXPECT_THAT(
+      Result.front().CommandLine,
+      ElementsAre(EndsWith("clang-tool"), "-DFOO=BAR", "--baz", "/foo/bar.cc"));
+}
+
 TEST(ParseFixedCompilationDatabase, ReturnsNullOnEmptyArgumentList) {
   int Argc = 0;
   std::string ErrorMsg;