Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -5297,6 +5297,14 @@
         IsNan2008(false), IsSingleFloat(false), FloatABI(HardFloat),
         DspRev(NoDSP), HasMSA(false), HasFP64(false), ABI(ABIStr) {}
 
+  bool isNaN2008Default() const {
+    return CPU == "mips32r6" || CPU == "mips64r6";
+  }
+
+  bool isFP64Default() const {
+    return CPU == "mips32r6" || ABI == "n32" || ABI == "n64" || ABI == "64";
+  }
+
   StringRef getABI() const override { return ABI; }
   bool setCPU(const std::string &Name) override {
     bool IsMips32 = getTriple().getArch() == llvm::Triple::mips ||
@@ -5467,11 +5475,11 @@
                             DiagnosticsEngine &Diags) override {
     IsMips16 = false;
     IsMicromips = false;
-    IsNan2008 = false;
+    IsNan2008 = isNaN2008Default();
     IsSingleFloat = false;
     FloatABI = HardFloat;
     DspRev = NoDSP;
-    HasFP64 = ABI == "n32" || ABI == "n64" || ABI == "64";
+    HasFP64 = isFP64Default();
 
     for (std::vector<std::string>::iterator it = Features.begin(),
          ie = Features.end(); it != ie; ++it) {
@@ -5495,6 +5503,8 @@
         HasFP64 = false;
       else if (*it == "+nan2008")
         IsNan2008 = true;
+      else if (*it == "-nan2008")
+        IsNan2008 = false;
     }
 
     // Remove front-end specific options.
Index: test/Preprocessor/init.c
===================================================================
--- test/Preprocessor/init.c
+++ test/Preprocessor/init.c
@@ -2864,6 +2864,16 @@
 // MIPS64-NOMFP64:#define _MIPS_FPSET 32
 // MIPS64-NOMFP64:#define __mips_fpr 32
 //
+// RUN: %clang_cc1 -target-cpu mips32r6 \
+// RUN:   -E -dM -triple=mips-none-none < /dev/null \
+// RUN:   | FileCheck -check-prefix MIPS-XXR6 %s
+// RUN: %clang_cc1 -target-cpu mips64r6 \
+// RUN:   -E -dM -triple=mips64-none-none < /dev/null \
+// RUN:   | FileCheck -check-prefix MIPS-XXR6 %s
+// MIPS-XXR6:#define _MIPS_FPSET 32
+// MIPS-XXR6:#define __mips_fpr 64
+// MIPS-XXR6:#define __mips_nan2008 1
+//
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=msp430-none-none < /dev/null | FileCheck -check-prefix MSP430 %s
 //
 // MSP430:#define MSP430 1