diff --git a/compiler/optimizing/intrinsics_arm.cc b/compiler/optimizing/intrinsics_arm.cc
index de04175..5e5e973 100644
--- a/compiler/optimizing/intrinsics_arm.cc
+++ b/compiler/optimizing/intrinsics_arm.cc
@@ -1055,17 +1055,22 @@
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ CompareAndBranchIfZero(arg, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ CompareAndBranchIfZero(arg, &return_false);
+  }
 
-  // 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.
-  __ ldr(temp, Address(str, class_offset));
-  __ ldr(temp1, Address(arg, class_offset));
-  __ cmp(temp, ShifterOperand(temp1));
-  __ b(&return_false, NE);
+  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.
+    __ ldr(temp, Address(str, class_offset));
+    __ ldr(temp1, Address(arg, class_offset));
+    __ cmp(temp, ShifterOperand(temp1));
+    __ b(&return_false, NE);
+  }
 
   // Load lengths of this and argument strings.
   __ ldr(temp, Address(str, count_offset));
diff --git a/compiler/optimizing/intrinsics_arm64.cc b/compiler/optimizing/intrinsics_arm64.cc
index 6cd1726..30ab111 100644
--- a/compiler/optimizing/intrinsics_arm64.cc
+++ b/compiler/optimizing/intrinsics_arm64.cc
@@ -1327,21 +1327,26 @@
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ Cbz(arg, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ Cbz(arg, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ Cmp(str, arg);
   __ B(&return_true, eq);
 
-  // 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.
-  __ Ldr(temp, MemOperand(str.X(), class_offset));
-  __ Ldr(temp1, MemOperand(arg.X(), class_offset));
-  __ Cmp(temp, temp1);
-  __ B(&return_false, ne);
+  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.
+    __ Ldr(temp, MemOperand(str.X(), class_offset));
+    __ Ldr(temp1, MemOperand(arg.X(), class_offset));
+    __ Cmp(temp, temp1);
+    __ B(&return_false, ne);
+  }
 
   // Load lengths of this and argument strings.
   __ Ldr(temp, MemOperand(str.X(), count_offset));
diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 99bc40e..e530b90 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -1319,11 +1319,11 @@
     __ j(kEqual, &return_false);
   }
 
-  // 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.
   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.
     __ movl(ecx, Address(str, class_offset));
     __ cmpl(ecx, Address(arg, class_offset));
     __ j(kNotEqual, &return_false);
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index 06e9cc2..2b626be 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -1416,17 +1416,22 @@
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ testl(arg, arg);
-  __ j(kEqual, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ testl(arg, arg);
+    __ j(kEqual, &return_false);
+  }
 
-  // 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.
-  __ movl(rcx, Address(str, class_offset));
-  __ cmpl(rcx, Address(arg, class_offset));
-  __ j(kNotEqual, &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.
+    __ movl(rcx, Address(str, class_offset));
+    __ cmpl(rcx, Address(arg, class_offset));
+    __ j(kNotEqual, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ cmpl(str, arg);
diff --git a/test/536-checker-intrinsic-optimization/src/Main.java b/test/536-checker-intrinsic-optimization/src/Main.java
index 15a9504..24ed2fe 100644
--- a/test/536-checker-intrinsic-optimization/src/Main.java
+++ b/test/536-checker-intrinsic-optimization/src/Main.java
@@ -107,8 +107,28 @@
   }
 
   /// CHECK-START-X86: boolean Main.stringArgumentNotNull(java.lang.Object) disassembly (after)
-  /// CHECK:          InvokeVirtual {{.*\.equals.*}}
+  /// CHECK:          InvokeVirtual {{.*\.equals.*}} intrinsic:StringEquals
   /// CHECK-NOT:      test
+
+  /// CHECK-START-X86_64: boolean Main.stringArgumentNotNull(java.lang.Object) disassembly (after)
+  /// CHECK:          InvokeVirtual {{.*\.equals.*}} intrinsic:StringEquals
+  /// CHECK-NOT:      test
+
+  /// CHECK-START-ARM: boolean Main.stringArgumentNotNull(java.lang.Object) disassembly (after)
+  /// CHECK:          InvokeVirtual {{.*\.equals.*}} intrinsic:StringEquals
+  // CompareAndBranchIfZero() may emit either CBZ or CMP+BEQ.
+  /// CHECK-NOT:      cbz
+  /// CHECK-NOT:      cmp {{r\d+}}, #0
+  // Terminate the scope for the CHECK-NOT search at the reference or length comparison,
+  // whichever comes first.
+  /// CHECK:          cmp {{r\d+}}, {{r\d+}}
+
+  /// CHECK-START-ARM64: boolean Main.stringArgumentNotNull(java.lang.Object) disassembly (after)
+  /// CHECK:          InvokeVirtual {{.*\.equals.*}} intrinsic:StringEquals
+  /// CHECK-NOT:      cbz
+  // Terminate the scope for the CHECK-NOT search at the reference or length comparison,
+  // whichever comes first.
+  /// CHECK:          cmp {{w.*,}} {{w.*}}
   public static boolean stringArgumentNotNull(Object obj) {
     obj.getClass();
     return "foo".equals(obj);
@@ -116,12 +136,53 @@
 
   // Test is very brittle as it depends on the order we emit instructions.
   /// CHECK-START-X86: boolean Main.stringArgumentIsString() disassembly (after)
-  /// CHECK:      InvokeVirtual
-  /// CHECK:      test
-  /// CHECK:      jz/eq
+  /// CHECK:          InvokeVirtual intrinsic:StringEquals
+  /// CHECK:          test
+  /// CHECK:          jz/eq
   // Check that we don't try to compare the classes.
-  /// CHECK-NOT:  mov
-  /// CHECK:      cmp
+  /// CHECK-NOT:      mov
+  /// CHECK:          cmp
+
+  // Test is very brittle as it depends on the order we emit instructions.
+  /// CHECK-START-X86_64: boolean Main.stringArgumentIsString() disassembly (after)
+  /// CHECK:          InvokeVirtual intrinsic:StringEquals
+  /// CHECK:          test
+  /// CHECK:          jz/eq
+  // Check that we don't try to compare the classes.
+  /// CHECK-NOT:      mov
+  /// CHECK:          cmp
+
+  // Test is brittle as it depends on the class offset being 0.
+  /// CHECK-START-ARM: boolean Main.stringArgumentIsString() disassembly (after)
+  /// CHECK:          InvokeVirtual intrinsic:StringEquals
+  /// CHECK:          {{cbz|cmp}}
+  // Check that we don't try to compare the classes.
+  // The dissassembler currently explicitly emits the offset 0 but don't rely on it.
+  // We want to terminate the CHECK-NOT search after two CMPs, one for reference
+  // equality and one for length comparison but these may be emitted in different order,
+  // so repeat the check twice.
+  /// CHECK-NOT:      ldr{{(|.w)}} {{r\d+}}, [{{r\d+}}]
+  /// CHECK-NOT:      ldr{{(|.w)}} {{r\d+}}, [{{r\d+}}, #0]
+  /// CHECK:          cmp {{r\d+}}, {{r\d+}}
+  /// CHECK-NOT:      ldr{{(|.w)}} {{r\d+}}, [{{r\d+}}]
+  /// CHECK-NOT:      ldr{{(|.w)}} {{r\d+}}, [{{r\d+}}, #0]
+  /// CHECK:          cmp {{r\d+}}, {{r\d+}}
+
+  // Test is brittle as it depends on the class offset being 0.
+  /// CHECK-START-ARM64: boolean Main.stringArgumentIsString() disassembly (after)
+  /// CHECK:          InvokeVirtual intrinsic:StringEquals
+  /// CHECK:          cbz
+  // Check that we don't try to compare the classes.
+  // The dissassembler currently does not explicitly emits the offset 0 but don't rely on it.
+  // We want to terminate the CHECK-NOT search after two CMPs, one for reference
+  // equality and one for length comparison but these may be emitted in different order,
+  // so repeat the check twice.
+  /// CHECK-NOT:      ldr {{w\d+}}, [{{x\d+}}]
+  /// CHECK-NOT:      ldr {{w\d+}}, [{{x\d+}}, #0]
+  /// CHECK:          cmp {{w\d+}}, {{w\d+}}
+  /// CHECK-NOT:      ldr {{w\d+}}, [{{x\d+}}]
+  /// CHECK-NOT:      ldr {{w\d+}}, [{{x\d+}}, #0]
+  /// CHECK:          cmp {{w\d+}}, {{w\d+}}
   public static boolean stringArgumentIsString() {
     return "foo".equals(myString);
   }