Index: llvm/trunk/lib/Target/Mips/MipsInstrFPU.td
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsInstrFPU.td
+++ llvm/trunk/lib/Target/Mips/MipsInstrFPU.td
@@ -390,12 +390,15 @@
 }
 
 // Indexed loads and stores.
-let Predicates = [HasFPIdx, HasStdEnc] in {
+// Base register + offset register addressing mode (indicated by "x" in the
+// instruction mnemonic) is disallowed under NaCl.
+let Predicates = [HasFPIdx, HasStdEnc, IsNotNaCl] in {
   def LWXC1 : MMRel, LWXC1_FT<"lwxc1", FGR32Opnd, II_LWXC1, load>, LWXC1_FM<0>;
   def SWXC1 : MMRel, SWXC1_FT<"swxc1", FGR32Opnd, II_SWXC1, store>, SWXC1_FM<8>;
 }
 
-let Predicates = [HasFPIdx, NotFP64bit, HasStdEnc, NotInMicroMips] in {
+let Predicates = [HasFPIdx, NotFP64bit, HasStdEnc, NotInMicroMips,
+                  IsNotNaCl] in {
   def LDXC1 : LWXC1_FT<"ldxc1", AFGR64Opnd, II_LDXC1, load>, LWXC1_FM<1>;
   def SDXC1 : SWXC1_FT<"sdxc1", AFGR64Opnd, II_SDXC1, store>, SWXC1_FM<9>;
 }
@@ -407,7 +410,7 @@
 }
 
 // Load/store doubleword indexed unaligned.
-let Predicates = [NotFP64bit, HasStdEnc] in {
+let Predicates = [NotFP64bit, HasStdEnc, IsNotNaCl] in {
   def LUXC1 : MMRel, LWXC1_FT<"luxc1", AFGR64Opnd, II_LUXC1>, LWXC1_FM<0x5>;
   def SUXC1 : MMRel, SWXC1_FT<"suxc1", AFGR64Opnd, II_SUXC1>, SWXC1_FM<0xd>;
 }
Index: llvm/trunk/lib/Target/Mips/MipsInstrInfo.td
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsInstrInfo.td
+++ llvm/trunk/lib/Target/Mips/MipsInstrInfo.td
@@ -187,6 +187,7 @@
                       AssemblerPredicate<"!FeatureMicroMips">;
 def IsLE           :  Predicate<"Subtarget.isLittle()">;
 def IsBE           :  Predicate<"!Subtarget.isLittle()">;
+def IsNotNaCl    :    Predicate<"!Subtarget.isTargetNaCl()">;
 
 class MipsPat<dag pattern, dag result> : Pat<pattern, result> {
   let Predicates = [HasStdEnc];
Index: llvm/trunk/lib/Target/Mips/MipsSubtarget.h
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsSubtarget.h
+++ llvm/trunk/lib/Target/Mips/MipsSubtarget.h
@@ -125,6 +125,7 @@
 
   MipsTargetMachine *TM;
 
+  Triple TargetTriple;
 public:
   virtual bool enablePostRAScheduler(CodeGenOpt::Level OptLevel,
                                      AntiDepBreakMode& Mode,
@@ -207,6 +208,8 @@
 
   bool os16() const { return Os16;};
 
+  bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
+
 // for now constant islands are on for the whole compilation unit but we only
 // really use them if in addition we are in mips16 mode
 //
Index: llvm/trunk/lib/Target/Mips/MipsSubtarget.cpp
===================================================================
--- llvm/trunk/lib/Target/Mips/MipsSubtarget.cpp
+++ llvm/trunk/lib/Target/Mips/MipsSubtarget.cpp
@@ -72,7 +72,7 @@
   InMips16Mode(false), InMips16HardFloat(Mips16HardFloat),
   InMicroMipsMode(false), HasDSP(false), HasDSPR2(false),
   AllowMixed16_32(Mixed16_32 | Mips_Os16), Os16(Mips_Os16), HasMSA(false),
-  RM(_RM), OverrideMode(NoOverride), TM(_TM)
+  RM(_RM), OverrideMode(NoOverride), TM(_TM), TargetTriple(TT)
 {
   std::string CPUName = CPU;
   if (CPUName.empty())
Index: llvm/trunk/test/CodeGen/Mips/fp-indexed-ls.ll
===================================================================
--- llvm/trunk/test/CodeGen/Mips/fp-indexed-ls.ll
+++ llvm/trunk/test/CodeGen/Mips/fp-indexed-ls.ll
@@ -1,4 +1,6 @@
 ; RUN: llc -march=mipsel -mcpu=mips32r2 < %s | FileCheck %s
+; RUN: llc -mtriple=mipsel-none-nacl-gnu -mcpu=mips32r2 < %s \
+; RUN:  | FileCheck %s -check-prefix=CHECK-NACL
 
 %struct.S = type <{ [4 x float] }>
 %struct.S2 = type <{ [4 x double] }>
@@ -13,6 +15,7 @@
 define float @foo0(float* nocapture %b, i32 %o) nounwind readonly {
 entry:
 ; CHECK: lwxc1
+; CHECK-NACL-NOT: lwxc1
   %arrayidx = getelementptr inbounds float* %b, i32 %o
   %0 = load float* %arrayidx, align 4
   ret float %0
@@ -21,6 +24,7 @@
 define double @foo1(double* nocapture %b, i32 %o) nounwind readonly {
 entry:
 ; CHECK: ldxc1
+; CHECK-NACL-NOT: ldxc1
   %arrayidx = getelementptr inbounds double* %b, i32 %o
   %0 = load double* %arrayidx, align 8
   ret double %0
@@ -37,6 +41,7 @@
 define void @foo3(float* nocapture %b, i32 %o) nounwind {
 entry:
 ; CHECK: swxc1
+; CHECK-NACL-NOT: swxc1
   %0 = load float* @gf, align 4
   %arrayidx = getelementptr inbounds float* %b, i32 %o
   store float %0, float* %arrayidx, align 4
@@ -46,6 +51,7 @@
 define void @foo4(double* nocapture %b, i32 %o) nounwind {
 entry:
 ; CHECK: sdxc1
+; CHECK-NACL-NOT: sdxc1
   %0 = load double* @gd, align 8
   %arrayidx = getelementptr inbounds double* %b, i32 %o
   store double %0, double* %arrayidx, align 8