Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -324,8 +324,6 @@
   ...
   #endif
 
-.. _languageextensions-builtin-macros:
-
 Builtin Macros
 ==============
 
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -56,11 +56,6 @@
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 
-- The ``__VERSION__`` macro has been removed.
-  Previously this macro was set to a string aiming to achieve compatibility with 
-  GCC 4.2.1, but that should no longer be necessary. To get Clang's version,
-  use the :ref:`clang namespaced version macros <languageextensions-builtin-macros>`.
-
 - ...
 
 
@@ -84,11 +79,6 @@
 
 - ...
 
-Removed Compiler Options
-------------------------
-
-- ...
-
 New Pragmas in Clang
 --------------------
 
Index: clang/lib/Basic/Version.cpp
===================================================================
--- clang/lib/Basic/Version.cpp
+++ clang/lib/Basic/Version.cpp
@@ -136,6 +136,8 @@
 }
 
 std::string getClangFullCPPVersion() {
+  // The version string we report in __VERSION__ is just a compacted version of
+  // the one we report on the command line.
   std::string buf;
   llvm::raw_string_ostream OS(buf);
 #ifdef CLANG_VENDOR
Index: clang/lib/Frontend/InitPreprocessor.cpp
===================================================================
--- clang/lib/Frontend/InitPreprocessor.cpp
+++ clang/lib/Frontend/InitPreprocessor.cpp
@@ -604,6 +604,12 @@
   // Support for #pragma redefine_extname (Sun compatibility)
   Builder.defineMacro("__PRAGMA_REDEFINE_EXTNAME", "1");
 
+  // As sad as it is, enough software depends on the __VERSION__ for version
+  // checks that it is necessary to report 4.2.1 (the base GCC version we claim
+  // compatibility with) first.
+  Builder.defineMacro("__VERSION__", "\"4.2.1 Compatible " +
+                      Twine(getClangFullCPPVersion()) + "\"");
+
   // Initialize language-specific preprocessor defines.
 
   // Standard conforming mode?
Index: clang/test/Index/complete-exprs.c
===================================================================
--- clang/test/Index/complete-exprs.c
+++ clang/test/Index/complete-exprs.c
@@ -27,6 +27,7 @@
 // RUN: c-index-test -code-completion-at=%s:7:10 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:10 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: NotImplemented:{TypedText __PRETTY_FUNCTION__} (65)
+// CHECK-CC1: macro definition:{TypedText __VERSION__} (70)
 // CHECK-CC1: FunctionDecl:{ResultType int}{TypedText f}{LeftParen (}{Placeholder int}{RightParen )} (12) (unavailable)
 // CHECK-CC1-NOT: NotImplemented:{TypedText float} (65)
 // CHECK-CC1: ParmDecl:{ResultType int}{TypedText j} (8)
@@ -38,6 +39,7 @@
 // RUN: c-index-test -code-completion-at=%s:7:18 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: c-index-test -code-completion-at=%s:7:22 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: c-index-test -code-completion-at=%s:7:2 -Xclang -code-completion-patterns %s | FileCheck -check-prefix=CHECK-CC2 %s
+// CHECK-CC2: macro definition:{TypedText __VERSION__} (70)
 // CHECK-CC2: FunctionDecl:{ResultType int}{TypedText f}{LeftParen (}{Placeholder int}{RightParen )} (50)
 // CHECK-CC2: NotImplemented:{TypedText float} (50)
 // CHECK-CC2: ParmDecl:{ResultType int}{TypedText j} (34)
Index: clang/test/Preprocessor/init.c
===================================================================
--- clang/test/Preprocessor/init.c
+++ clang/test/Preprocessor/init.c
@@ -101,6 +101,7 @@
 // COMMON:#define __ORDER_PDP_ENDIAN__ 3412
 // COMMON:#define __STDC_HOSTED__ 1
 // COMMON:#define __STDC__ 1
+// COMMON:#define __VERSION__ {{.*}}
 // COMMON:#define __clang__ 1
 // COMMON:#define __clang_major__ {{[0-9]+}}
 // COMMON:#define __clang_minor__ {{[0-9]+}}
@@ -8168,6 +8169,7 @@
 // SPARC:#define __UINT_LEAST8_MAX__ 255
 // SPARC:#define __UINT_LEAST8_TYPE__ unsigned char
 // SPARC:#define __USER_LABEL_PREFIX__
+// SPARC:#define __VERSION__ "4.2.1 Compatible{{.*}}
 // SPARC:#define __WCHAR_MAX__ 2147483647
 // SPARC:#define __WCHAR_TYPE__ int
 // SPARC:#define __WCHAR_WIDTH__ 32
@@ -9039,6 +9041,7 @@
 // X86_64-CLOUDABI:#define __UINT_LEAST8_MAX__ 255
 // X86_64-CLOUDABI:#define __UINT_LEAST8_TYPE__ unsigned char
 // X86_64-CLOUDABI:#define __USER_LABEL_PREFIX__
+// X86_64-CLOUDABI:#define __VERSION__ "4.2.1 Compatible{{.*}}
 // X86_64-CLOUDABI:#define __WCHAR_MAX__ 2147483647
 // X86_64-CLOUDABI:#define __WCHAR_TYPE__ int
 // X86_64-CLOUDABI:#define __WCHAR_WIDTH__ 32
@@ -10040,6 +10043,7 @@
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_MAX__ 255
 // WEBASSEMBLY-NEXT:#define __UINT_LEAST8_TYPE__ unsigned char
 // WEBASSEMBLY-NEXT:#define __USER_LABEL_PREFIX__
+// WEBASSEMBLY-NEXT:#define __VERSION__ "{{.*}}"
 // WEBASSEMBLY-NEXT:#define __WCHAR_MAX__ 2147483647
 // WEBASSEMBLY-NEXT:#define __WCHAR_TYPE__ int
 // WEBASSEMBLY-NOT:#define __WCHAR_UNSIGNED__
Index: clang/utils/builtin-defines.c
===================================================================
--- clang/utils/builtin-defines.c
+++ clang/utils/builtin-defines.c
@@ -49,6 +49,7 @@
 #undef __INT8_TYPE__
 #undef __SSP__
 #undef __APPLE_CC__
+#undef __VERSION__
 #undef __clang__
 #undef __llvm__
 #undef __nocona