--- a/js/src/jit/BaselineCompiler.cpp
+++ b/js/src/jit/BaselineCompiler.cpp
@@ -1291,16 +1291,39 @@ BaselineCompiler::emit_JSOP_HOLE()
 
 bool
 BaselineCompiler::emit_JSOP_NULL()
 {
     frame.push(NullValue());
     return true;
 }
 
+typedef bool (*ThrowCheckIsObjectFn)(JSContext*, CheckIsObjectKind);
+static const VMFunction ThrowCheckIsObjectInfo =
+    FunctionInfo<ThrowCheckIsObjectFn>(ThrowCheckIsObject);
+
+bool
+BaselineCompiler::emit_JSOP_CHECKISOBJ()
+{
+    frame.syncStack(0);
+    masm.loadValue(frame.addressOfStackValue(frame.peek(-1)), R0);
+
+    Label ok;
+    masm.branchTestObject(Assembler::Equal, R0, &ok);
+
+    prepareVMCall();
+
+    pushArg(Imm32(GET_UINT8(pc)));
+    if (!callVM(ThrowCheckIsObjectInfo))
+        return false;
+
+    masm.bind(&ok);
+    return true;
+}
+
 typedef bool (*ThrowUninitializedThisFn)(JSContext*, BaselineFrame* frame);
 static const VMFunction ThrowUninitializedThisInfo =
     FunctionInfo<ThrowUninitializedThisFn>(BaselineThrowUninitializedThis);
 
 bool
 BaselineCompiler::emit_JSOP_CHECKTHIS()
 {
     frame.syncStack(0);

--- a/js/src/jit/BaselineCompiler.h
+++ b/js/src/jit/BaselineCompiler.h
@@ -205,16 +205,17 @@ namespace jit {
     _(JSOP_RESUME)             \
     _(JSOP_CALLEE)             \
     _(JSOP_GETRVAL)            \
     _(JSOP_SETRVAL)            \
     _(JSOP_RETRVAL)            \
     _(JSOP_RETURN)             \
     _(JSOP_FUNCTIONTHIS)       \
     _(JSOP_GLOBALTHIS)         \
+    _(JSOP_CHECKISOBJ)         \
     _(JSOP_CHECKTHIS)          \
     _(JSOP_CHECKRETURN)        \
     _(JSOP_NEWTARGET)          \
     _(JSOP_SUPERCALL)          \
     _(JSOP_SPREADSUPERCALL)    \
     _(JSOP_THROWSETCONST)      \
     _(JSOP_THROWSETALIASEDCONST) \
     _(JSOP_INITHIDDENPROP_GETTER) \