diff --git a/include/clang/Driver/Options.def b/include/clang/Driver/Options.def
index 7e77a1a..bfa5a66 100644
--- a/include/clang/Driver/Options.def
+++ b/include/clang/Driver/Options.def
@@ -424,11 +424,11 @@
 OPTION("-fastcp", fastcp, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fastf", fastf, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fast", fast, Flag, f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fblocks", fblocks, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fblocks", fblocks, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fbootclasspath=", fbootclasspath_EQ, Joined, f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fbuiltin", fbuiltin, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fbuiltin", fbuiltin, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fclasspath=", fclasspath_EQ, Joined, f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fcommon", fcommon, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fcommon", fcommon, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fcompile-resource=", fcompile_resource_EQ, Joined, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fconstant-cfstrings", fconstant_cfstrings, Flag, clang_ignored_f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fcreate-profile", fcreate_profile, Flag, f_Group, INVALID, "", 0, 0, 0)
@@ -459,10 +459,10 @@
 OPTION("-fmudflap", fmudflap, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fnested-functions", fnested_functions, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fnext-runtime", fnext_runtime, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fno-blocks", fno_blocks, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fno-builtin", fno_builtin, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fno-blocks", fno_blocks, Flag, f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fno-builtin", fno_builtin, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fno-caret-diagnostics", fno_caret_diagnostics, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fno-common", fno_common, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fno-common", fno_common, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fno-constant-cfstrings", fno_constant_cfstrings, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fno-eliminate-unused-debug-symbols", fno_eliminate_unused_debug_symbols, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fno-inline-functions", fno_inline_functions, Flag, clang_ignored_f_Group, INVALID, "", 0, 0, 0)
@@ -488,7 +488,7 @@
 OPTION("-force_cpusubtype_ALL", force__cpusubtype__ALL, Flag, INVALID, INVALID, "", 0, 0, 0)
 OPTION("-force_flat_namespace", force__flat__namespace, Flag, INVALID, INVALID, "", 0, 0, 0)
 OPTION("-foutput-class-dir=", foutput_class_dir_EQ, Joined, f_Group, INVALID, "", 0, 0, 0)
-OPTION("-fpascal-strings", fpascal_strings, Flag, clang_f_Group, INVALID, "", 0, 0, 0)
+OPTION("-fpascal-strings", fpascal_strings, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fpch-preprocess", fpch_preprocess, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fpic", fpic, Flag, f_Group, INVALID, "", 0, 0, 0)
 OPTION("-fpie", fpie, Flag, f_Group, INVALID, "", 0, 0, 0)
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index e26bb9e..dd3a00e 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -357,8 +357,34 @@
     CmdArgs.push_back(A->getValue(Args));
   }
 
+  // Forward -f options which we can pass directly.
   Args.AddAllArgs(CmdArgs, options::OPT_clang_f_Group);
 
+  // Forward -f options with positive and negative forms; we translate
+  // these by hand.
+
+  // -fbuiltin is default, only pass non-default.
+  if (!Args.hasFlag(options::OPT_fbuiltin, options::OPT_fno_builtin))
+    CmdArgs.push_back("-fbuiltin=0");
+
+  // -fblocks default varies depending on platform and language;
+  // -always pass if specified.
+  if (Arg *A = Args.getLastArg(options::OPT_fblocks, options::OPT_fno_blocks)) {
+    if (A->getOption().matches(options::OPT_fblocks))
+      CmdArgs.push_back("-fblocks");
+    else
+      CmdArgs.push_back("-fblocks=0");
+  }
+
+  // -fno-pascal-strings is default, only pass non-default.
+  if (Args.hasFlag(options::OPT_fpascal_strings, 
+                      options::OPT_fno_pascal_strings))
+    CmdArgs.push_back("-fpascal-strings");
+
+  // -fcommon is default, only pass non-default.
+  if (!Args.hasFlag(options::OPT_fcommon, options::OPT_fno_common))
+    CmdArgs.push_back("-fno-common");
+
   // If tool chain translates fpascal-strings, we want to back
   // translate here.
   // FIXME: This is gross; that translation should be pulled from the
diff --git a/test/Sema/exprs.c b/test/Sema/exprs.c
index ae4c37c..9db8c92 100644
--- a/test/Sema/exprs.c
+++ b/test/Sema/exprs.c
@@ -1,4 +1,4 @@
-// RUN: clang-cc %s -verify -pedantic -fsyntax-only -fno-blocks
+// RUN: clang-cc %s -verify -pedantic -fsyntax-only -fblocks=0
 
 // PR1966
 _Complex double test1() {
diff --git a/test/Sema/unused-expr.c b/test/Sema/unused-expr.c
index b3d6efb..9c231e9 100644
--- a/test/Sema/unused-expr.c
+++ b/test/Sema/unused-expr.c
@@ -1,4 +1,4 @@
-// RUN: clang-cc -fsyntax-only -verify -fno-math-errno %s
+// RUN: clang-cc -fsyntax-only -verify -fmath-errno=0 %s
 
 int foo(int X, int Y);
 
diff --git a/tools/clang-cc/clang-cc.cpp b/tools/clang-cc/clang-cc.cpp
index d257c43..9260afe 100644
--- a/tools/clang-cc/clang-cc.cpp
+++ b/tools/clang-cc/clang-cc.cpp
@@ -323,15 +323,13 @@
                             "freestanding environment"));
 
 static llvm::cl::opt<bool>
-AllowBuiltins("fbuiltin",
-              llvm::cl::desc("Disable implicit builtin knowledge of functions"),
-              llvm::cl::init(true), llvm::cl::AllowInverse);
+AllowBuiltins("fbuiltin", llvm::cl::init(true),
+             llvm::cl::desc("Disable implicit builtin knowledge of functions"));
 
 
 static llvm::cl::opt<bool>
-MathErrno("fmath-errno", 
-          llvm::cl::desc("Require math functions to respect errno"),
-          llvm::cl::init(true), llvm::cl::AllowInverse);
+MathErrno("fmath-errno", llvm::cl::init(true),
+          llvm::cl::desc("Require math functions to respect errno"));
 
 //===----------------------------------------------------------------------===//
 // Language Options
@@ -546,9 +544,7 @@
                                       "elements or different element types"));
 
 static llvm::cl::opt<bool>
-EnableBlocks("fblocks", llvm::cl::desc("enable the 'blocks' language feature"),
-             llvm::cl::ValueDisallowed, llvm::cl::AllowInverse,
-             llvm::cl::ZeroOrMore);
+EnableBlocks("fblocks", llvm::cl::desc("enable the 'blocks' language feature"));
 
 static llvm::cl::opt<bool>
 EnableHeinousExtensions("fheinous-gnu-extensions",