diff --git a/js/src/jit/LIR-Common.h b/js/src/jit/LIR-Common.h
index fcc29eee2c81..d231a5f3bedc 100644
--- a/js/src/jit/LIR-Common.h
+++ b/js/src/jit/LIR-Common.h
@@ -128,6 +128,25 @@ class LMoveGroup : public LInstructionHelper<0, 0, 0>
     }
 };
 
+// Constructs a SIMD value with 4 components (e.g. int32x4, float32x4).
+class LSimdValueX4 : public LInstructionHelper<1, 4, 0>
+{
+  public:
+    LIR_HEADER(SimdValueX4)
+    LSimdValueX4(const LAllocation &x, const LAllocation &y,
+                 const LAllocation &z, const LAllocation &w)
+    {
+        setOperand(0, x);
+        setOperand(1, y);
+        setOperand(2, z);
+        setOperand(3, w);
+    }
+
+    MSimdValueX4 *mir() const {
+        return mir_->toSimdValueX4();
+    }
+};
+
 // Extracts an element from a given SIMD int32x4 lane.
 class LSimdExtractElementI : public LInstructionHelper<1, 1, 0>
 {
diff --git a/js/src/jit/LOpcodes.h b/js/src/jit/LOpcodes.h
index e2aaa7a186a6..fd4305059985 100644
--- a/js/src/jit/LOpcodes.h
+++ b/js/src/jit/LOpcodes.h
@@ -16,6 +16,7 @@
     _(Pointer)                      \
     _(Double)                       \
     _(Float32)                      \
+    _(SimdValueX4)                  \
     _(SimdExtractElementI)          \
     _(SimdExtractElementF)          \
     _(Value)                        \
diff --git a/js/src/jit/Lowering.cpp b/js/src/jit/Lowering.cpp
index 7b73f9bde075..8e15ab3c6a08 100644
--- a/js/src/jit/Lowering.cpp
+++ b/js/src/jit/Lowering.cpp
@@ -3650,6 +3650,17 @@ LIRGenerator::visitRecompileCheck(MRecompileCheck *ins)
     return assignSafepoint(lir, ins);
 }
 
+bool
+LIRGenerator::visitSimdValueX4(MSimdValueX4 *ins)
+{
+    LAllocation x = useRegisterAtStart(ins->getOperand(0));
+    LAllocation y = useRegisterAtStart(ins->getOperand(1));
+    LAllocation z = useRegisterAtStart(ins->getOperand(2));
+    LAllocation w = useRegisterAtStart(ins->getOperand(3));
+
+    return define(new(alloc()) LSimdValueX4(x, y, z, w), ins);
+}
+
 bool
 LIRGenerator::visitSimdExtractElement(MSimdExtractElement *ins)
 {
diff --git a/js/src/jit/Lowering.h b/js/src/jit/Lowering.h
index 973c9cb839e1..97a60e95ed58 100644
--- a/js/src/jit/Lowering.h
+++ b/js/src/jit/Lowering.h
@@ -265,6 +265,7 @@ class LIRGenerator : public LIRGeneratorSpecific
     bool visitGetDOMMember(MGetDOMMember *ins);
     bool visitRecompileCheck(MRecompileCheck *ins);
     bool visitSimdExtractElement(MSimdExtractElement *ins);
+    bool visitSimdValueX4(MSimdValueX4 *ins);
 };
 
 } // namespace jit
diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index cdec8be10792..19cf3503cf5f 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -13,6 +13,7 @@
 #define jit_MIR_h
 
 #include "mozilla/Array.h"
+#include "mozilla/DebugOnly.h"
 
 #include "jit/CompilerRoot.h"
 #include "jit/FixedList.h"
@@ -1233,6 +1234,42 @@ class MConstant : public MNullaryInstruction
     ALLOW_CLONE(MConstant)
 };
 
+// Generic constructor of SIMD valuesX4.
+class MSimdValueX4 : public MQuaternaryInstruction
+{
+  protected:
+    MSimdValueX4(MIRType type, MDefinition *x, MDefinition *y, MDefinition *z, MDefinition *w)
+      : MQuaternaryInstruction(x, y, z, w)
+    {
+        JS_ASSERT(IsSimdType(type));
+        mozilla::DebugOnly<MIRType> scalarType = SimdTypeToScalarType(type);
+        JS_ASSERT(scalarType == x->type());
+        JS_ASSERT(scalarType == y->type());
+        JS_ASSERT(scalarType == z->type());
+        JS_ASSERT(scalarType == w->type());
+
+        setMovable();
+        setResultType(type);
+    }
+
+  public:
+    INSTRUCTION_HEADER(SimdValueX4)
+
+    static MSimdValueX4 *New(TempAllocator &alloc, MIRType type, MDefinition *x,
+                             MDefinition *y, MDefinition *z, MDefinition *w)
+    {
+        return new(alloc) MSimdValueX4(type, x, y, z, w);
+    }
+
+    AliasSet getAliasSet() const {
+        return AliasSet::None();
+    }
+
+    bool congruentTo(const MDefinition *ins) const {
+        return congruentIfOperandsEqual(ins);
+    }
+};
+
 // Extracts a lane element from a given vector type, given by its lane symbol.
 class MSimdExtractElement : public MUnaryInstruction
 {
diff --git a/js/src/jit/MOpcodes.h b/js/src/jit/MOpcodes.h
index 1e08c0ad4548..2fb01340168a 100644
--- a/js/src/jit/MOpcodes.h
+++ b/js/src/jit/MOpcodes.h
@@ -12,6 +12,7 @@ namespace jit {
 
 #define MIR_OPCODE_LIST(_)                                                  \
     _(Constant)                                                             \
+    _(SimdValueX4)                                                          \
     _(SimdExtractElement)                                                   \
     _(CloneLiteral)                                                         \
     _(Parameter)                                                            \
diff --git a/js/src/jit/ParallelSafetyAnalysis.cpp b/js/src/jit/ParallelSafetyAnalysis.cpp
index fa927d0c4536..1aec7a62c742 100644
--- a/js/src/jit/ParallelSafetyAnalysis.cpp
+++ b/js/src/jit/ParallelSafetyAnalysis.cpp
@@ -112,6 +112,7 @@ class ParallelSafetyVisitor : public MDefinitionVisitor
     // obviously safe for now.  We can loosen as we need.
 
     SAFE_OP(Constant)
+    SAFE_OP(SimdValueX4)
     SAFE_OP(SimdExtractElement)
     UNSAFE_OP(CloneLiteral)
     SAFE_OP(Parameter)
diff --git a/js/src/jit/arm/CodeGenerator-arm.h b/js/src/jit/arm/CodeGenerator-arm.h
index ca2e3e0030a3..ed66e286752c 100644
--- a/js/src/jit/arm/CodeGenerator-arm.h
+++ b/js/src/jit/arm/CodeGenerator-arm.h
@@ -227,6 +227,7 @@ class CodeGeneratorARM : public CodeGeneratorShared
 
   public:
     // Unimplemented SIMD instructions
+    bool visitSimdValueX4(LSimdValueX4 *lir) { MOZ_ASSUME_UNREACHABLE("NYI"); }
     bool visitSimdExtractElementI(LSimdExtractElementI *ins) { MOZ_ASSUME_UNREACHABLE("NYI"); }
     bool visitSimdExtractElementF(LSimdExtractElementF *ins) { MOZ_ASSUME_UNREACHABLE("NYI"); }
 };
diff --git a/js/src/jit/shared/CodeGenerator-x86-shared.cpp b/js/src/jit/shared/CodeGenerator-x86-shared.cpp
index 077ca7c61d56..72e50e053f63 100644
--- a/js/src/jit/shared/CodeGenerator-x86-shared.cpp
+++ b/js/src/jit/shared/CodeGenerator-x86-shared.cpp
@@ -2053,6 +2053,41 @@ CodeGeneratorX86Shared::visitNegF(LNegF *ins)
     return true;
 }
 
+bool
+CodeGeneratorX86Shared::visitSimdValueX4(LSimdValueX4 *ins)
+{
+    FloatRegister output = ToFloatRegister(ins->output());
+
+    MSimdValueX4 *mir = ins->mir();
+    JS_ASSERT(IsSimdType(mir->type()));
+    JS_STATIC_ASSERT(sizeof(float) == sizeof(int32_t));
+
+    masm.reserveStack(Simd128DataSize);
+    // TODO see bug 1051860 for possible optimizations.
+    switch (mir->type()) {
+      case MIRType_Int32x4: {
+        for (size_t i = 0; i < 4; ++i) {
+            Register r = ToRegister(ins->getOperand(i));
+            masm.store32(r, Address(StackPointer, i * sizeof(int32_t)));
+        }
+        masm.loadAlignedInt32x4(Address(StackPointer, 0), output);
+        break;
+      }
+      case MIRType_Float32x4: {
+        for (size_t i = 0; i < 4; ++i) {
+            FloatRegister r = ToFloatRegister(ins->getOperand(i));
+            masm.storeFloat32(r, Address(StackPointer, i * sizeof(float)));
+        }
+        masm.loadAlignedFloat32x4(Address(StackPointer, 0), output);
+        break;
+      }
+      default: MOZ_ASSUME_UNREACHABLE("Unknown SIMD kind");
+    }
+
+    masm.freeStack(Simd128DataSize);
+    return true;
+}
+
 bool
 CodeGeneratorX86Shared::visitSimdExtractElementI(LSimdExtractElementI *ins)
 {
diff --git a/js/src/jit/shared/CodeGenerator-x86-shared.h b/js/src/jit/shared/CodeGenerator-x86-shared.h
index 6d33809f36bb..c87626d2b03d 100644
--- a/js/src/jit/shared/CodeGenerator-x86-shared.h
+++ b/js/src/jit/shared/CodeGenerator-x86-shared.h
@@ -205,6 +205,7 @@ class CodeGeneratorX86Shared : public CodeGeneratorShared
     bool visitNegF(LNegF *lir);
 
     // SIMD operators
+    bool visitSimdValueX4(LSimdValueX4 *lir);
     bool visitSimdExtractElementI(LSimdExtractElementI *lir);
     bool visitSimdExtractElementF(LSimdExtractElementF *lir);