Index: packages/Python/lldbsuite/test/lang/objc/objc-checker/TestObjCCheckers.py
===================================================================
--- packages/Python/lldbsuite/test/lang/objc/objc-checker/TestObjCCheckers.py
+++ packages/Python/lldbsuite/test/lang/objc/objc-checker/TestObjCCheckers.py
@@ -18,13 +18,15 @@
 
     mydir = TestBase.compute_mydir(__file__)
 
+    NO_DEBUG_INFO_TESTCASE = True
+
     def setUp(self):
         # Call super's setUp().
         TestBase.setUp(self)
 
         # Find the line number to break for main.c.
         self.source_name = 'main.m'
-
+    
     @skipUnlessDarwin
     @add_test_categories(['pyapi'])
     def test_objc_checker(self):
@@ -77,3 +79,16 @@
         # Make sure the error is helpful:
         err_string = expr_error.GetCString()
         self.assertTrue("selector" in err_string)
+
+        #
+        # Check that we correctly insert the checker for an
+        # ObjC method with the struct return convention.
+        # Getting this wrong would cause us to call the checker
+        # with the wrong arguments, and the checker would crash
+        # So I'm just checking "expression runs successfully" here:
+        #
+        expr_value = frame.EvaluateExpression("[my_simple getBigStruct]", False)
+        expr_error = expr_value.GetError()
+        
+        self.assertTrue(expr_error.Success())
+        
Index: packages/Python/lldbsuite/test/lang/objc/objc-checker/main.m
===================================================================
--- packages/Python/lldbsuite/test/lang/objc/objc-checker/main.m
+++ packages/Python/lldbsuite/test/lang/objc/objc-checker/main.m
@@ -1,11 +1,19 @@
 #import <Foundation/Foundation.h>
 
+// This should be a big enough struct that it will force
+// the struct return convention:
+typedef struct BigStruct {
+  float a, b, c, d, e, f, g, h, i, j, k, l;
+} BigStruct;
+
+
 @interface Simple : NSObject
 {
   int _value;
 }
 - (int) value;
 - (void) setValue: (int) newValue;
+- (BigStruct) getBigStruct;
 @end
 
 @implementation Simple
@@ -18,6 +26,13 @@
 {
   _value = newValue;
 }
+
+- (BigStruct) getBigStruct
+{
+  BigStruct big_struct = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0,
+                          7.0, 8.0, 9.0, 10.0, 11.0, 12.0};
+  return big_struct;
+}
 @end
 
 int main ()
Index: source/Expression/IRDynamicChecks.cpp
===================================================================
--- source/Expression/IRDynamicChecks.cpp
+++ source/Expression/IRDynamicChecks.cpp
@@ -424,8 +424,15 @@
     switch (msgSend_types[inst]) {
     case eMsgSend:
     case eMsgSend_fpret:
-      target_object = call_inst->getArgOperand(0);
-      selector = call_inst->getArgOperand(1);
+      // On arm64, clang uses objc_msgSend for scalar and struct return
+      // calls.  The call instruction will record which was used.
+      if (call_inst->hasStructRetAttr()) {
+        target_object = call_inst->getArgOperand(1);
+        selector = call_inst->getArgOperand(2);
+      } else {
+        target_object = call_inst->getArgOperand(0);
+        selector = call_inst->getArgOperand(1);
+      }
       break;
     case eMsgSend_stret:
       target_object = call_inst->getArgOperand(1);