diff --git a/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/named_function_arguments_split.ll.expected b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/named_function_arguments_split.ll.expected
--- a/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/named_function_arguments_split.ll.expected
+++ b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/named_function_arguments_split.ll.expected
@@ -1,14 +1,13 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
 ; Check that we split named function arguments correctly into a separate CHECK line,
 ; ensuring the opening parenthesis is on the label name, avoiding incorrect label
 ; matches if function names are not prefix free.
-; Note: This is a precommitted test, the current result is incorrect.
 ;
 ; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
 ;
 define i32 @"foo"(i32 %named) {
-; CHECK-LABEL: define i32 @foo
-; CHECK-SAME: (i32 [[NAMED:%.*]]) {
+; CHECK-LABEL: define i32 @foo(
+; CHECK-SAME: i32 [[NAMED:%.*]]) {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    ret i32 [[NAMED]]
 ;
diff --git a/llvm/test/tools/UpdateTestChecks/update_test_checks/named_function_arguments_split.test b/llvm/test/tools/UpdateTestChecks/update_test_checks/named_function_arguments_split.test
--- a/llvm/test/tools/UpdateTestChecks/update_test_checks/named_function_arguments_split.test
+++ b/llvm/test/tools/UpdateTestChecks/update_test_checks/named_function_arguments_split.test
@@ -1,7 +1,7 @@
 # REQUIRES: x86-registered-target
 ## Basic test checking that update_test_checks.py works correctly
-# RUN: cp -f %S/Inputs/named_function_arguments_split.ll %t.ll && %update_test_checks %t.ll --version=2
+# RUN: cp -f %S/Inputs/named_function_arguments_split.ll %t.ll && %update_test_checks %t.ll --version=3
 # RUN: diff -u %t.ll %S/Inputs/named_function_arguments_split.ll.expected
 ## Check that running the script again does not change the result:
-# RUN: %update_test_checks %t.ll --version=2
+# RUN: %update_test_checks %t.ll --version=3
 # RUN: diff -u %t.ll %S/Inputs/named_function_arguments_split.ll.expected
diff --git a/llvm/utils/UpdateTestChecks/common.py b/llvm/utils/UpdateTestChecks/common.py
--- a/llvm/utils/UpdateTestChecks/common.py
+++ b/llvm/utils/UpdateTestChecks/common.py
@@ -24,8 +24,10 @@
 1: Initial version, used by tests that don't specify --version explicitly.
 2: --function-signature is now enabled by default and also checks return
    type/attributes.
+3: Opening parenthesis of function args is kept on the first LABEL line
+   in case arguments are split to a separate SAME line.
 """
-DEFAULT_VERSION = 2
+DEFAULT_VERSION = 3
 
 
 class Regex(object):
@@ -1277,13 +1279,27 @@
                 )[0]
             func_name_separator = func_dict[checkprefix][func_name].func_name_separator
             if "[[" in args_and_sig:
+                # Captures in label lines are not supported, thus split into a -LABEL
+                # and a separate -SAME line that contains the arguments with captures.
+                args_and_sig_prefix = ""
+                if version >= 3 and args_and_sig.startswith("("):
+                    # Ensure the "(" separating function name and arguments is in the
+                    # label line. This is required in case of function names that are
+                    # prefixes of each other. Otherwise, the label line for "foo" might
+                    # incorrectly match on "foo.specialized".
+                    args_and_sig_prefix = args_and_sig[0]
+                    args_and_sig = args_and_sig[1:]
+
+                # Removing args_and_sig from the label match line requires
+                # func_name_separator to be empty. Otherwise, the match will not work.
+                assert func_name_separator == ""
                 output_lines.append(
                     check_label_format
                     % (
                         checkprefix,
                         funcdef_attrs_and_ret,
                         func_name,
-                        "",
+                        args_and_sig_prefix,
                         func_name_separator,
                     )
                 )