diff --git a/clang/include/clang/Config/config.h.cmake b/clang/include/clang/Config/config.h.cmake
--- a/clang/include/clang/Config/config.h.cmake
+++ b/clang/include/clang/Config/config.h.cmake
@@ -45,6 +45,9 @@
 #cmakedefine CLANG_CONFIG_FILE_SYSTEM_DIR "${CLANG_CONFIG_FILE_SYSTEM_DIR}"
 #cmakedefine CLANG_CONFIG_FILE_USER_DIR "${CLANG_CONFIG_FILE_USER_DIR}"
 
+/* Name of the env variable for the configuration file */
+#cmakedefine ENV_CONFIG_FILE_NAME "${ENV_CONFIG_FILE_NAME}"
+
 /* Default <path> to all compiler invocations for --sysroot=<path>. */
 #define DEFAULT_SYSROOT "${DEFAULT_SYSROOT}"
 
diff --git a/clang/include/clang/Driver/Driver.h b/clang/include/clang/Driver/Driver.h
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -702,6 +702,12 @@
   /// \returns true if error occurred.
   bool loadDefaultConfigFiles(llvm::cl::ExpansionContext &ExpCtx);
 
+  /// Tries to load options from configuration file specified by environment
+  //  variable.
+  //
+  //  \returns true if error occurred.
+  bool readConfigFileFromEnv();
+
   /// Read options from the specified file.
   ///
   /// \param [in] FileName File to read.
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1034,6 +1034,35 @@
   return false;
 }
 
+bool Driver::readConfigFileFromEnv() {
+  llvm::cl::ExpansionContext ExpCtx(Saver.getAllocator(),
+                                    llvm::cl::tokenizeConfigFile);
+  ExpCtx.setVFS(&getVFS());
+  std::string EnvCfgName = "CONFIG_FILE";
+
+#if defined(ENV_CONFIG_FILE_NAME)
+  EnvCfgName = ENV_CONFIG_FILE_NAME;
+#endif
+  const char *EnvCfgFileName = getenv(EnvCfgName.c_str());
+
+  if (!EnvCfgFileName)
+    return false;
+
+  std::string CfgFileName = EnvCfgFileName;
+  if (CfgFileName.empty()) {
+    Diag(diag::err_drv_cannot_read_config_file) << CfgFileName << "";
+    return true;
+  }
+
+  // If argument contains directory separator, treat it as a path to
+  // configuration file.
+  SmallString<128> CfgFilePath;
+  if (llvm::sys::path::is_relative(CfgFileName))
+    llvm::sys::fs::current_path(CfgFilePath);
+  llvm::sys::path::append(CfgFilePath, CfgFileName);
+  return readConfigFile(CfgFilePath, ExpCtx);
+}
+
 bool Driver::loadConfigFiles() {
   llvm::cl::ExpansionContext ExpCtx(Saver.getAllocator(),
                                     llvm::cl::tokenizeConfigFile);
@@ -1099,6 +1128,9 @@
     }
   }
 
+  if (ConfigFiles.empty())
+    return readConfigFileFromEnv();
+
   // No error occurred.
   return false;
 }
diff --git a/clang/test/Driver/config-file-from-env.c b/clang/test/Driver/config-file-from-env.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/config-file-from-env.c
@@ -0,0 +1,51 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: mkdir %t/empty_dir
+// RUN: echo "-Wall" > %t/c.cfg
+// RUN: echo "-ffast-math" > %t/cxx.cfg
+// RUN: touch %t/unreadable.cfg
+// RUN: chmod 000 %t/unreadable.cfg
+// RUN: touch %t/test.c
+// RUN: touch %t/test.cpp
+
+// RUN: env CONFIG_FILE=%t/c.cfg %clang -S %t/test.c -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-C1
+// CHECK-C1: Configuration file: {{.*}}/c.cfg
+// CHECK-C1: -Wall
+
+// RUN: env CONFIG_FILE=%t/unreadable.cfg not %clang -S %t/test.c -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-C2
+// CHECK-C2: error: cannot read configuration file '{{.*}}/unreadable.cfg'
+
+// RUN: env CONFIG_FILE=%t/c.cfg %clang -S %t/test.c --config %S/Inputs/config-1.cfg -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-C3
+// CHECK-C3: Configuration file: {{.*}}/config-1.cfg
+// CHECK-C3: -Werror
+// CHECK-C3-NOT: -Wall
+
+// RUN: env CONFIG_FILE= not %clang -S %t/test.c -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-C4
+// CHECK-C4: error: cannot read configuration file ''
+
+// RUN: env CONFIG_FILE=%t/empty_dir not %clang -S %t/test.c -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-C5
+// CHECK-C5: error: configuration file '{{.*}}/empty_dir' cannot be opened: not a regular file
+
+// RUN: env CONFIG_FILE=%t/cxx.cfg %clang++ -S %t/test.cpp -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX1
+// CHECK-CXX1: Configuration file: {{.*}}/cxx.cfg
+// CHECK-CXX1: -ffast-math
+
+// RUN: env CONFIG_FILE=%t/unreadable.cfg not %clang++ -S %t/test.cpp -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX2
+// CHECK-CXX2: error: cannot read configuration file '{{.*}}/unreadable.cfg'
+
+// RUN: env CONFIG_FILE=%t/cxx.cfg %clang++ -S %t/test.cpp --config %S/Inputs/config-1.cfg -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX3
+// CHECK-CXX3: Configuration file: {{.*}}/config-1.cfg
+// CHECK-CXX3: -Werror
+// CHECK-CXX3-NOT: -ffast-math
+
+// RUN: env CONFIG_FILE= not %clang++ -S %t/test.cpp -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX4
+// CHECK-CXX4: error: cannot read configuration file ''
+
+// RUN: env CONFIG_FILE=%t/empty_dir not %clang++ -S %t/test.cpp -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX5
+// CHECK-CXX5: error: configuration file '{{.*}}/empty_dir' cannot be opened: not a regular file
+
+// RUN: env CONFIG_FILE=%t/c.cfg %clang++ --config=%t/cxx.cfg -S %t/test.cpp -o /dev/null -### 2>&1 | FileCheck %s -check-prefix CHECK-CXX6
+// CHECK-CXX6-NOT: Configuration file: {{.*}}/c.cfg
+// CHECK-CXX6-NOT: -Wall
+
+// RUN: rm -rf %t