diff --git a/compiler/optimizing/intrinsics_mips.cc b/compiler/optimizing/intrinsics_mips.cc
index 64a6840..5999677 100644
--- a/compiler/optimizing/intrinsics_mips.cc
+++ b/compiler/optimizing/intrinsics_mips.cc
@@ -1989,20 +1989,24 @@
     __ LoadConst32(out, 1);
     return;
   }
-
-  // Check if input is null, return false if it is.
-  __ Beqz(arg, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ Beqz(arg, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ Beq(str, arg, &return_true);
 
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
-  __ Lw(temp1, str, class_offset);
-  __ Lw(temp2, arg, class_offset);
-  __ Bne(temp1, temp2, &return_false);
+  if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
+    __ Lw(temp1, str, class_offset);
+    __ Lw(temp2, arg, class_offset);
+    __ Bne(temp1, temp2, &return_false);
+  }
 
   // Load `count` fields of this and argument strings.
   __ Lw(temp1, str, count_offset);
diff --git a/compiler/optimizing/intrinsics_mips64.cc b/compiler/optimizing/intrinsics_mips64.cc
index 3888828..10da5c2 100644
--- a/compiler/optimizing/intrinsics_mips64.cc
+++ b/compiler/optimizing/intrinsics_mips64.cc
@@ -1593,19 +1593,24 @@
     return;
   }
 
-  // Check if input is null, return false if it is.
-  __ Beqzc(arg, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ Beqzc(arg, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ Beqc(str, arg, &return_true);
 
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
-  __ Lw(temp1, str, class_offset);
-  __ Lw(temp2, arg, class_offset);
-  __ Bnec(temp1, temp2, &return_false);
+  if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
+    __ Lw(temp1, str, class_offset);
+    __ Lw(temp2, arg, class_offset);
+    __ Bnec(temp1, temp2, &return_false);
+  }
 
   // Load `count` fields of this and argument strings.
   __ Lw(temp1, str, count_offset);