diff --git a/MODULE.bazel b/MODULE.bazel
index 780eb2651f37..11683d38a880 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -83,8 +83,8 @@ git_override(
     build_file_content = "# empty",
     # We pin to specific upstream commits and try to track top-of-tree
     # reasonably closely rather than pinning to a specific release.
-    # HEAD as of 2026-04-01.
-    commit = "b71eacea7687f68c11299e3bda5654fbbaa1e20e",
+    # HEAD as of 2026-05-14.
+    commit = "9a4faee1068c09efbf837cfb7b0f5693b24635f4",
     patch_cmds = ["echo \"module(name='llvm-raw')\" > MODULE.bazel"],
     patch_strip = 1,
     patches = [
diff --git a/testing/file_test/testdata/lsp_keywords.carbon b/testing/file_test/testdata/lsp_keywords.carbon
index cc340a70aa8f..f7f4c22af6e1 100644
--- a/testing/file_test/testdata/lsp_keywords.carbon
+++ b/testing/file_test/testdata/lsp_keywords.carbon
@@ -41,7 +41,7 @@
 // CHECK:STDERR:
 // CHECK:STDERR: Content-Length: 53
 // CHECK:STDERR:
-// CHECK:STDERR: {"jsonrpc":"2.0","method":"baz","multi":0,"line":1}
+// CHECK:STDERR: {"jsonrpc":"2.0","method":"baz","line":1,"multi":0}
 // CHECK:STDERR:
 // CHECK:STDERR: Content-Length: 64
 // CHECK:STDERR:
diff --git a/toolchain/check/cpp/type_mapping.cpp b/toolchain/check/cpp/type_mapping.cpp
index 9c2ed4a29603..2b3dfbf33d5c 100644
--- a/toolchain/check/cpp/type_mapping.cpp
+++ b/toolchain/check/cpp/type_mapping.cpp
@@ -587,7 +587,8 @@ static auto InventCompoundClangArg(Context& context, FormInfo form,
     auto rbrace_loc = compound_loc;
 
     auto* init_list = new (context.ast_context()) clang::InitListExpr(
-        context.ast_context(), lbrace_loc, inits, rbrace_loc);
+        context.ast_context(), lbrace_loc, inits, rbrace_loc,
+        /* isExplicit= */ true);
     init_list->setType(context.ast_context().VoidTy);
     return init_list;
   };
diff --git a/toolchain/check/testdata/interop/cpp/basics/bad_flags.carbon b/toolchain/check/testdata/interop/cpp/basics/bad_flags.carbon
index 0ab862dcc308..b70df9b5314d 100644
--- a/toolchain/check/testdata/interop/cpp/basics/bad_flags.carbon
+++ b/toolchain/check/testdata/interop/cpp/basics/bad_flags.carbon
@@ -12,7 +12,7 @@
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/basics/bad_flags.carbon
 // CHECK:STDERR: error: unable to read PCH file does_not_exist.pch: 'No such file or directory' [CppInteropParseError]
 // CHECK:STDERR:
-// CHECK:STDERR: error: PCH file 'does_not_exist.pch' not found: module file not found [CppInteropParseError]
+// CHECK:STDERR: error: PCH file 'does_not_exist.pch' not found [CppInteropParseError]
 // CHECK:STDERR:
 
 // --- fail_bad_args.carbon
diff --git a/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon b/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
index 912481fa8ae3..55346eda4256 100644
--- a/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
@@ -12,7 +12,7 @@
 // TIP: To dump output, run:
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
 // CHECK:STDOUT: TranslationUnitDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc>
-// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> Carbon
+// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> referenced Carbon external-linkage
 
 // --- thunk_with_args_and_return.carbon
 
@@ -21,7 +21,7 @@ library "[[@TEST_NAME]]";
 import Cpp;
 
 fn F(i: i32) -> i32 {
-// CHECK:STDOUT: | `-FunctionDecl {{0x[a-f0-9]+}} <thunk_with_args_and_return.carbon:[[@LINE-1]]:21> col:21 used F 'int (int)' inline
+// CHECK:STDOUT: | `-FunctionDecl {{0x[a-f0-9]+}} <thunk_with_args_and_return.carbon:[[@LINE-1]]:21> col:21 used F 'int (int)' inline internal-linkage
 // CHECK:STDOUT: |   |-ParmVarDecl {{0x[a-f0-9]+}} <col:21> col:21 used 'int'
 // CHECK:STDOUT: |   |-CompoundStmt {{0x[a-f0-9]+}} <col:21>
 // CHECK:STDOUT: |   | |-DeclStmt {{0x[a-f0-9]+}} <col:21>
@@ -35,7 +35,7 @@ fn F(i: i32) -> i32 {
 // CHECK:STDOUT: |   |   `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
 // CHECK:STDOUT: |   |-AlwaysInlineAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit always_inline
 // CHECK:STDOUT: |   `-InternalLinkageAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit
-// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <line:35:1, line:37:1> line:35:5 G 'int (int)'
+// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <line:35:1, line:37:1> line:35:5 G 'int (int)' external-linkage
 // CHECK:STDOUT:   |-ParmVarDecl {{0x[a-f0-9]+}} <col:7, col:11> col:11 used i 'int'
 // CHECK:STDOUT:   `-CompoundStmt {{0x[a-f0-9]+}} <col:14, line:37:1>
 // CHECK:STDOUT:     `-ReturnStmt {{0x[a-f0-9]+}} <line:36:3, col:21>
diff --git a/toolchain/check/testdata/interop/cpp/function/import/thunk_ast.carbon b/toolchain/check/testdata/interop/cpp/function/import/thunk_ast.carbon
index a706fd14102b..32b9f7d19d3e 100644
--- a/toolchain/check/testdata/interop/cpp/function/import/thunk_ast.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/import/thunk_ast.carbon
@@ -12,14 +12,14 @@
 // TIP: To dump output, run:
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/function/import/thunk_ast.carbon
 // CHECK:STDOUT: TranslationUnitDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc>
-// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> Carbon
+// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> Carbon external-linkage
 
 // --- thunk_required.h
 
 auto foo(short a) -> void;
-// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <./thunk_required.h:[[@LINE-1]]:1, col:22> col:6 used foo 'auto (short) -> void'
+// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <./thunk_required.h:[[@LINE-1]]:1, col:22> col:6 used foo 'auto (short) -> void' external-linkage
 // CHECK:STDOUT: | `-ParmVarDecl {{0x[a-f0-9]+}} <col:10, col:16> col:16 a 'short'
-// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <col:6> col:6 foo__carbon_thunk 'void (short * _Nonnull)' inline
+// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <col:6> col:6 foo__carbon_thunk 'void (short * _Nonnull)' inline internal-linkage
 // CHECK:STDOUT:   |-ParmVarDecl {{0x[a-f0-9]+}} <col:6> col:6 used a 'short * _Nonnull':'short *'
 // CHECK:STDOUT:   |-ReturnStmt {{0x[a-f0-9]+}} <col:6>
 // CHECK:STDOUT:   | `-CallExpr {{0x[a-f0-9]+}} <col:6> 'void'
@@ -33,7 +33,7 @@ auto foo(short a) -> void;
 // CHECK:STDOUT:   |-InternalLinkageAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit
 // CHECK:STDOUT:   `-AsmLabelAttr {{0x[a-f0-9]+}} <col:6> Implicit "_Z3foos.carbon_thunk._"
 // CHECK:STDOUT: TranslationUnitDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc>
-// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> Carbon
+// CHECK:STDOUT: |-NamespaceDecl {{0x[a-f0-9]+}} <<invalid sloc>> <invalid sloc> Carbon external-linkage
 
 // --- import_thunk_required.carbon
 
@@ -48,8 +48,8 @@ fn F() {
 // --- return_thunk_required.h
 
 auto foo() -> short;
-// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <./return_thunk_required.h:[[@LINE-1]]:1, col:15> col:6 used foo 'auto () -> short'
-// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <col:6> col:6 foo__carbon_thunk 'void (short * _Nonnull)' inline
+// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <./return_thunk_required.h:[[@LINE-1]]:1, col:15> col:6 used foo 'auto () -> short' external-linkage
+// CHECK:STDOUT: `-FunctionDecl {{0x[a-f0-9]+}} <col:6> col:6 foo__carbon_thunk 'void (short * _Nonnull)' inline internal-linkage
 // CHECK:STDOUT:   |-ParmVarDecl {{0x[a-f0-9]+}} <col:6> col:6 used return 'short * _Nonnull':'short *'
 // CHECK:STDOUT:   |-CXXNewExpr {{0x[a-f0-9]+}} <col:6> 'short *' global Function {{0x[a-f0-9]+}} 'operator new' 'void *(__size_t, void *) noexcept'
 // CHECK:STDOUT:   | |-CallExpr {{0x[a-f0-9]+}} <col:6> 'short'
diff --git a/toolchain/lower/testdata/array/assign_return_value.carbon b/toolchain/lower/testdata/array/assign_return_value.carbon
index 66d83e460756..ac8a1362b750 100644
--- a/toolchain/lower/testdata/array/assign_return_value.carbon
+++ b/toolchain/lower/testdata/array/assign_return_value.carbon
@@ -69,18 +69,17 @@ fn Run() {
 // CHECK:STDOUT:   ret void, !dbg !32
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/array/base.carbon b/toolchain/lower/testdata/array/base.carbon
index 564071a9deb7..30374e430fec 100644
--- a/toolchain/lower/testdata/array/base.carbon
+++ b/toolchain/lower/testdata/array/base.carbon
@@ -119,8 +119,8 @@ fn Run() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 4, 3, 2, 1, 0 }
@@ -128,7 +128,6 @@ fn Run() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/array/field.carbon b/toolchain/lower/testdata/array/field.carbon
index 3a55822e1583..4a4eac3b536f 100644
--- a/toolchain/lower/testdata/array/field.carbon
+++ b/toolchain/lower/testdata/array/field.carbon
@@ -61,11 +61,11 @@ class A {
 // CHECK:STDOUT:   ret i32 %.loc24_20.2, !dbg !24
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/array/layout.carbon b/toolchain/lower/testdata/array/layout.carbon
index 9d385f8ce732..8ffdaf714f08 100644
--- a/toolchain/lower/testdata/array/layout.carbon
+++ b/toolchain/lower/testdata/array/layout.carbon
@@ -127,11 +127,11 @@ var c: array(Core.Int(257), 5) = (1, 2, 3, 4, 5);
 // CHECK:STDOUT:   ret void, !dbg !8
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/builtins/types.carbon b/toolchain/lower/testdata/builtins/types.carbon
index 63f278484b33..1bf145e1081a 100644
--- a/toolchain/lower/testdata/builtins/types.carbon
+++ b/toolchain/lower/testdata/builtins/types.carbon
@@ -44,7 +44,7 @@ fn Uses() {
 // CHECK:STDOUT: define void @_CUses.Main() #0 !dbg !4 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   call void @_CIntParam.Main(i32 1), !dbg !7
-// CHECK:STDOUT:   call void @_CFloatParam.Main(half 0xH3C00, float 1.000000e+00, double 1.000000e+00, fp128 0xL00000000000000003FFF000000000000), !dbg !8
+// CHECK:STDOUT:   call void @_CFloatParam.Main(half 1.000000e+00, float 1.000000e+00, double 1.000000e+00, fp128 1.000000e+00), !dbg !8
 // CHECK:STDOUT:   call void @_CBoolParam.Main(i1 false), !dbg !9
 // CHECK:STDOUT:   ret void, !dbg !10
 // CHECK:STDOUT: }
diff --git a/toolchain/lower/testdata/class/adapt.carbon b/toolchain/lower/testdata/class/adapt.carbon
index e9a9700e0de6..543c1d51e7e7 100644
--- a/toolchain/lower/testdata/class/adapt.carbon
+++ b/toolchain/lower/testdata/class/adapt.carbon
@@ -115,15 +115,14 @@ fn DoStuff(a: Int) -> Int {
 // CHECK:STDOUT:   ret void, !dbg !43
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/class/base.carbon b/toolchain/lower/testdata/class/base.carbon
index 42d0210b14e4..4bcbd2c1a18b 100644
--- a/toolchain/lower/testdata/class/base.carbon
+++ b/toolchain/lower/testdata/class/base.carbon
@@ -69,11 +69,11 @@ fn Convert(p: Derived*) -> Base* {
 // CHECK:STDOUT:   ret ptr %.loc32_11.2.base, !dbg !23
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/class/convert.carbon b/toolchain/lower/testdata/class/convert.carbon
index 503948087a93..c13b95f320ef 100644
--- a/toolchain/lower/testdata/class/convert.carbon
+++ b/toolchain/lower/testdata/class/convert.carbon
@@ -78,12 +78,11 @@ fn DoIt() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/class/field.carbon b/toolchain/lower/testdata/class/field.carbon
index f3eed183263d..f7fee9dcaeeb 100644
--- a/toolchain/lower/testdata/class/field.carbon
+++ b/toolchain/lower/testdata/class/field.carbon
@@ -202,15 +202,14 @@ fn Run() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -297,15 +296,14 @@ fn Run() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/class/generic.carbon b/toolchain/lower/testdata/class/generic.carbon
index fcd633fc8a31..0a597e0ad5ab 100644
--- a/toolchain/lower/testdata/class/generic.carbon
+++ b/toolchain/lower/testdata/class/generic.carbon
@@ -134,11 +134,11 @@ fn AccessTuple() -> (i32, i32, i32) {
 // CHECK:STDOUT:   ret void, !dbg !13
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -393,8 +393,8 @@ fn AccessTuple() -> (i32, i32, i32) {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr i1 @_CGetBool.C.Main.5662bbc72901b5f6(ptr %self) #0 !dbg !69 {
@@ -451,7 +451,6 @@ fn AccessTuple() -> (i32, i32, i32) {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/class/virtual.carbon b/toolchain/lower/testdata/class/virtual.carbon
index 257772d69ac5..174e8e5f87ba 100644
--- a/toolchain/lower/testdata/class/virtual.carbon
+++ b/toolchain/lower/testdata/class/virtual.carbon
@@ -334,11 +334,11 @@ fn Use() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
-// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #3
+// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.428e66b4e6184a3f:core.Destroy.Core", { 1, 0 }
@@ -347,8 +347,7 @@ fn Use() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -462,11 +461,11 @@ fn Use() {
 // CHECK:STDOUT:   ret void, !dbg !26
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -557,8 +556,8 @@ fn Use() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.dbf7676be30a7aa8:core.Destroy.Core", { 1, 0 }
@@ -566,7 +565,6 @@ fn Use() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -659,12 +657,11 @@ fn Use() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -793,16 +790,15 @@ fn Use() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
-// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #3
+// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -929,8 +925,8 @@ fn Use() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 3, 2, 1, 0 }
@@ -938,7 +934,6 @@ fn Use() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -1173,14 +1168,14 @@ fn Use() {
 // CHECK:STDOUT:   ret void, !dbg !53
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
-// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #4
+// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
@@ -1188,9 +1183,8 @@ fn Use() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { alwaysinline nounwind }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #4 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/for/bindings.carbon b/toolchain/lower/testdata/for/bindings.carbon
index 6d68f1acba2f..1e5f8dc29441 100644
--- a/toolchain/lower/testdata/for/bindings.carbon
+++ b/toolchain/lower/testdata/for/bindings.carbon
@@ -123,8 +123,8 @@ fn For() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @"_CNewCursor.EmptyRange.1ccc388edee5a786.Main:Iterate.Core.339d3adf5f5ecf68"(ptr %self) #0 !dbg !47 {
@@ -197,7 +197,6 @@ fn For() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/definition/destroy.carbon b/toolchain/lower/testdata/function/definition/destroy.carbon
index 6f810dcaff75..d262c7318c71 100644
--- a/toolchain/lower/testdata/function/definition/destroy.carbon
+++ b/toolchain/lower/testdata/function/definition/destroy.carbon
@@ -168,12 +168,11 @@ fn InitLet() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -249,18 +248,17 @@ fn InitLet() {
 // CHECK:STDOUT:   ret void, !dbg !28
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/definition/var_param.carbon b/toolchain/lower/testdata/function/definition/var_param.carbon
index 3275db0e5b85..d3c0e5c092da 100644
--- a/toolchain/lower/testdata/function/definition/var_param.carbon
+++ b/toolchain/lower/testdata/function/definition/var_param.carbon
@@ -117,8 +117,8 @@ fn Call() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.607f187990247af9:core.Destroy.Core", { 3, 2, 1, 0 }
@@ -128,7 +128,6 @@ fn Call() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/generic/call.carbon b/toolchain/lower/testdata/function/generic/call.carbon
index f9fb418ab118..6e44c9965127 100644
--- a/toolchain/lower/testdata/function/generic/call.carbon
+++ b/toolchain/lower/testdata/function/generic/call.carbon
@@ -93,8 +93,8 @@ fn G() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CF.Main.0c4ab795cec6cb27(ptr %_) #0 !dbg !41 {
@@ -127,7 +127,6 @@ fn G() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/generic/call_basic.carbon b/toolchain/lower/testdata/function/generic/call_basic.carbon
index 1d5d6f94c914..6c1d560abf69 100644
--- a/toolchain/lower/testdata/function/generic/call_basic.carbon
+++ b/toolchain/lower/testdata/function/generic/call_basic.carbon
@@ -109,11 +109,11 @@ fn M() {
 // CHECK:STDOUT:   ret void, !dbg !41
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @_CF.Main.b88d1103f417c6d4(i32 %_) #0 !dbg !42 {
@@ -269,8 +269,7 @@ fn M() {
 // CHECK:STDOUT: uselistorder ptr @_CH.Main.706e9f413f1bae3d, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/generic/call_method.carbon b/toolchain/lower/testdata/function/generic/call_method.carbon
index ad4945439c5d..ee42def5d069 100644
--- a/toolchain/lower/testdata/function/generic/call_method.carbon
+++ b/toolchain/lower/testdata/function/generic/call_method.carbon
@@ -58,8 +58,8 @@ fn CallF() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr i32 @_CF.C.Main.5662bbc72901b5f6(ptr %self, i32 %x) #0 !dbg !26 {
@@ -72,7 +72,6 @@ fn CallF() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/function/generic/call_recursive_basic.carbon b/toolchain/lower/testdata/function/generic/call_recursive_basic.carbon
index a2c7b2327ebc..191402c95cd0 100644
--- a/toolchain/lower/testdata/function/generic/call_recursive_basic.carbon
+++ b/toolchain/lower/testdata/function/generic/call_recursive_basic.carbon
@@ -106,11 +106,11 @@ fn M() {
 // CHECK:STDOUT:   ret void, !dbg !45
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr i32 @_CF.Main.5662bbc72901b5f6(i32 %x, i32 %count) #0 !dbg !46 {
@@ -180,8 +180,7 @@ fn M() {
 // CHECK:STDOUT: uselistorder ptr @_CF.Main.3ca635d99c484610, { 1, 2, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/global/class_obj.carbon b/toolchain/lower/testdata/global/class_obj.carbon
index 0d6218dd09a3..ab7ae925348c 100644
--- a/toolchain/lower/testdata/global/class_obj.carbon
+++ b/toolchain/lower/testdata/global/class_obj.carbon
@@ -27,11 +27,11 @@ var a: A = {};
 // CHECK:STDOUT:   ret void, !dbg !8
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/global/class_with_fun.carbon b/toolchain/lower/testdata/global/class_with_fun.carbon
index 05eccc3b876e..68c19564515e 100644
--- a/toolchain/lower/testdata/global/class_with_fun.carbon
+++ b/toolchain/lower/testdata/global/class_with_fun.carbon
@@ -31,7 +31,7 @@ var a: A = {};
 // CHECK:STDOUT:   ret void, !dbg !8
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
@@ -42,7 +42,7 @@ var a: A = {};
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/impl/impl.carbon b/toolchain/lower/testdata/impl/impl.carbon
index 0d51feb88a84..3ff75f211fab 100644
--- a/toolchain/lower/testdata/impl/impl.carbon
+++ b/toolchain/lower/testdata/impl/impl.carbon
@@ -170,19 +170,18 @@ impl C(B) as I {
 // CHECK:STDOUT:   ret void, !dbg !35
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/impl/import_facet.carbon b/toolchain/lower/testdata/impl/import_facet.carbon
index 67c630cc7a20..1d33b43acbc8 100644
--- a/toolchain/lower/testdata/impl/import_facet.carbon
+++ b/toolchain/lower/testdata/impl/import_facet.carbon
@@ -122,12 +122,11 @@ fn F(d: D(i32)) -> i32* {
 // CHECK:STDOUT:   ret ptr %2, !dbg !29
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/impl/thunk.carbon b/toolchain/lower/testdata/impl/thunk.carbon
index e36a8be8a730..b683395fc7ff 100644
--- a/toolchain/lower/testdata/impl/thunk.carbon
+++ b/toolchain/lower/testdata/impl/thunk.carbon
@@ -273,11 +273,11 @@ fn CallCallGeneric(c: C(()), b: B) -> A {
 // CHECK:STDOUT:   ret void, !dbg !35
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr void @"_CF.C.eb057aa32837c84e.Main:I.eb057aa32837c84e.Main.e43630e9a6c38c3f"(ptr sret({}) %return, ptr %self, ptr %_) #0 !dbg !36 {
@@ -294,7 +294,7 @@ fn CallCallGeneric(c: C(()), b: B) -> A {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: alwaysinline nounwind
-// CHECK:STDOUT: define linkonce_odr void @"_CF:thunk:I.1f5037c5d69ffaf4.Main:C.eb057aa32837c84e.Main:I.eb057aa32837c84e.Main.e43630e9a6c38c3f"(ptr sret({}) %return, ptr %self, ptr %x) #3 !dbg !47 {
+// CHECK:STDOUT: define linkonce_odr void @"_CF:thunk:I.1f5037c5d69ffaf4.Main:C.eb057aa32837c84e.Main:I.eb057aa32837c84e.Main.e43630e9a6c38c3f"(ptr sret({}) %return, ptr %self, ptr %x) #2 !dbg !47 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %.loc18_38.2.temp = alloca {}, align 8, !dbg !51
 // CHECK:STDOUT:   %.loc18_38.6.temp = alloca {}, align 8, !dbg !51
@@ -316,9 +316,8 @@ fn CallCallGeneric(c: C(()), b: B) -> A {
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 0, 1, 2, 6, 5, 4, 3 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #3 = { alwaysinline nounwind }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #2 = { alwaysinline nounwind }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/index/array_element_access.carbon b/toolchain/lower/testdata/index/array_element_access.carbon
index fd3c764cb2ad..b36e96ee81a0 100644
--- a/toolchain/lower/testdata/index/array_element_access.carbon
+++ b/toolchain/lower/testdata/index/array_element_access.carbon
@@ -104,11 +104,11 @@ fn Run() {
 // CHECK:STDOUT:   ret void, !dbg !41
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.7e389eab4a7e5487:core.Destroy.Core", { 2, 1, 0 }
@@ -117,8 +117,7 @@ fn Run() {
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 5, 4, 3, 2, 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon b/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
index 45e51c92607a..b9ed93579d91 100644
--- a/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
+++ b/toolchain/lower/testdata/interop/cpp/class/virtual_fn.carbon
@@ -162,7 +162,7 @@ void delete_new_Base() {
 // CHECK:STDOUT:   %vtable = load ptr, ptr %0, align 8, !tbaa !14
 // CHECK:STDOUT:   %vfn = getelementptr inbounds ptr, ptr %vtable, i64 1
 // CHECK:STDOUT:   %1 = load ptr, ptr %vfn, align 8
-// CHECK:STDOUT:   call void %1(ptr noundef nonnull align 8 dead_on_return(8) dereferenceable(8) %0) #8
+// CHECK:STDOUT:   call void %1(ptr noundef nonnull align 8 dereferenceable(8) %0) #8
 // CHECK:STDOUT:   br label %delete.end
 // CHECK:STDOUT:
 // CHECK:STDOUT: delete.end:                                       ; preds = %delete.notnull, %entry
@@ -265,7 +265,7 @@ void delete_new_Base() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN6Carbon5FinalD0Ev(ptr noundef nonnull align 8 dead_on_return(8) dereferenceable(8) %this) unnamed_addr #3 comdat align 2 {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN6Carbon5FinalD0Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #3 comdat align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !11
@@ -295,7 +295,7 @@ void delete_new_Base() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: inlinehint mustprogress nounwind uwtable
-// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN6Carbon4BaseD0Ev(ptr noundef nonnull align 8 dead_on_return(8) dereferenceable(8) %this) unnamed_addr #3 comdat align 2 {
+// CHECK:STDOUT: define linkonce_odr dso_local void @_ZN6Carbon4BaseD0Ev(ptr noundef nonnull align 8 dereferenceable(8) %this) unnamed_addr #3 comdat align 2 {
 // CHECK:STDOUT: entry:
 // CHECK:STDOUT:   %this.addr = alloca ptr, align 8
 // CHECK:STDOUT:   store ptr %this, ptr %this.addr, align 8, !tbaa !16
diff --git a/toolchain/lower/testdata/interop/cpp/operators.carbon b/toolchain/lower/testdata/interop/cpp/operators.carbon
index b00db6aacf14..37a7009b2feb 100644
--- a/toolchain/lower/testdata/interop/cpp/operators.carbon
+++ b/toolchain/lower/testdata/interop/cpp/operators.carbon
@@ -192,8 +192,8 @@ fn Driver(x: Cpp.A, y: Cpp.A) {
 // CHECK:STDOUT:   ret i1 %cmp
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #5
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: mustprogress nounwind uwtable
 // CHECK:STDOUT: define linkonce_odr dso_local noundef zeroext i1 @_Zne1AS_(i32 %x.coerce, i32 %y.coerce) #4 comdat {
@@ -226,7 +226,6 @@ fn Driver(x: Cpp.A, y: Cpp.A) {
 // CHECK:STDOUT: attributes #2 = { alwaysinline nounwind }
 // CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT: attributes #4 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #5 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
@@ -477,8 +476,8 @@ fn Driver(x: Cpp.A, y: Cpp.A) {
 // CHECK:STDOUT:   ret i1 %cmp
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #5
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: mustprogress nounwind uwtable
 // CHECK:STDOUT: define linkonce_odr dso_local noundef zeroext i1 @_Zle1AS_(i32 %x.coerce, i32 %y.coerce) #4 comdat {
@@ -554,7 +553,6 @@ fn Driver(x: Cpp.A, y: Cpp.A) {
 // CHECK:STDOUT: attributes #2 = { alwaysinline nounwind }
 // CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT: attributes #4 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #5 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
diff --git a/toolchain/lower/testdata/interop/cpp/parameters.carbon b/toolchain/lower/testdata/interop/cpp/parameters.carbon
index 02649c4aa022..b7364718fd3a 100644
--- a/toolchain/lower/testdata/interop/cpp/parameters.carbon
+++ b/toolchain/lower/testdata/interop/cpp/parameters.carbon
@@ -423,8 +423,8 @@ fn PassValueExpr(y: Cpp.Y) {
 // CHECK:STDOUT:
 // CHECK:STDOUT: declare void @_Z11pass_struct1X(i64, i32) #5
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #6
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #4
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
@@ -435,7 +435,6 @@ fn PassValueExpr(y: Cpp.Y) {
 // CHECK:STDOUT: attributes #3 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT: attributes #5 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
-// CHECK:STDOUT: attributes #6 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
diff --git a/toolchain/lower/testdata/interop/cpp/reference.carbon b/toolchain/lower/testdata/interop/cpp/reference.carbon
index 7cb67c4ca083..79055d2c7589 100644
--- a/toolchain/lower/testdata/interop/cpp/reference.carbon
+++ b/toolchain/lower/testdata/interop/cpp/reference.carbon
@@ -241,8 +241,8 @@ fn GetRefs() {
 // CHECK:STDOUT:   ret void, !dbg !46
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #6
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #5
 // CHECK:STDOUT:
 // CHECK:STDOUT: declare void @_Z9TakeCRRefO1C(ptr noundef nonnull align 1 dereferenceable(1)) #3
 // CHECK:STDOUT:
@@ -262,7 +262,6 @@ fn GetRefs() {
 // CHECK:STDOUT: attributes #3 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #4 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #5 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #6 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
diff --git a/toolchain/lower/testdata/interop/cpp/reverse/class.carbon b/toolchain/lower/testdata/interop/cpp/reverse/class.carbon
index a473d98c0b2b..27861d14e464 100644
--- a/toolchain/lower/testdata/interop/cpp/reverse/class.carbon
+++ b/toolchain/lower/testdata/interop/cpp/reverse/class.carbon
@@ -510,14 +510,13 @@ fn G() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #4
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #1 = { alwaysinline nounwind }
 // CHECK:STDOUT: attributes #2 = { nounwind }
 // CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #4 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
diff --git a/toolchain/lower/testdata/interop/cpp/std_initializer_list.carbon b/toolchain/lower/testdata/interop/cpp/std_initializer_list.carbon
index 828f2cab777d..b295b53b18cf 100644
--- a/toolchain/lower/testdata/interop/cpp/std_initializer_list.carbon
+++ b/toolchain/lower/testdata/interop/cpp/std_initializer_list.carbon
@@ -264,8 +264,8 @@ fn InitNontrivialDtor() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #4
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: mustprogress nounwind uwtable
 // CHECK:STDOUT: define linkonce_odr dso_local void @_ZN11vector_likeC2ESt16initializer_listIiE(ptr noundef nonnull align 1 dereferenceable(1) %this, ptr %list.coerce0, ptr %list.coerce1) unnamed_addr #2 comdat align 2 {
@@ -298,7 +298,6 @@ fn InitNontrivialDtor() {
 // CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #2 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #4 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
@@ -512,8 +511,8 @@ fn InitNontrivialDtor() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #3
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #4
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #3
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: mustprogress nounwind uwtable
 // CHECK:STDOUT: define linkonce_odr dso_local void @_ZN11vector_likeC2ESt16initializer_listIiE(ptr noundef nonnull align 1 dereferenceable(1) %this, ptr %list.coerce0, i64 %list.coerce1) unnamed_addr #2 comdat align 2 {
@@ -546,7 +545,6 @@ fn InitNontrivialDtor() {
 // CHECK:STDOUT: attributes #1 = { alwaysinline mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #2 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
 // CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #4 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1, !2, !3, !4}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!5}
diff --git a/toolchain/lower/testdata/let/copy_value_rep.carbon b/toolchain/lower/testdata/let/copy_value_rep.carbon
index db4e6ac7c5c1..4442ecd1d633 100644
--- a/toolchain/lower/testdata/let/copy_value_rep.carbon
+++ b/toolchain/lower/testdata/let/copy_value_rep.carbon
@@ -63,12 +63,11 @@ fn Run() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/let/tuple.carbon b/toolchain/lower/testdata/let/tuple.carbon
index f0f52ed1b200..f9531d2f9fd0 100644
--- a/toolchain/lower/testdata/let/tuple.carbon
+++ b/toolchain/lower/testdata/let/tuple.carbon
@@ -94,8 +94,8 @@ fn F() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
@@ -103,7 +103,6 @@ fn F() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/operators/assignment.carbon b/toolchain/lower/testdata/operators/assignment.carbon
index 56f52f5894f8..29e98423b330 100644
--- a/toolchain/lower/testdata/operators/assignment.carbon
+++ b/toolchain/lower/testdata/operators/assignment.carbon
@@ -74,15 +74,14 @@ fn G() -> (i32, i32) {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/packages/imported_type_completeness.carbon b/toolchain/lower/testdata/packages/imported_type_completeness.carbon
index a30809774493..e3582b5e3f9d 100644
--- a/toolchain/lower/testdata/packages/imported_type_completeness.carbon
+++ b/toolchain/lower/testdata/packages/imported_type_completeness.carbon
@@ -213,11 +213,11 @@ fn CallF() {
 // CHECK:STDOUT:   ret void, !dbg !8
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -311,8 +311,8 @@ fn CallF() {
 // CHECK:STDOUT:   ret void, !dbg !33
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr i11 @_CF.C.Main.0c4ab795cec6cb27(ptr %self) #0 !dbg !34 {
@@ -320,7 +320,7 @@ fn CallF() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
-// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #3
+// CHECK:STDOUT: declare ptr @llvm.load.relative.i32(ptr, i32) #2
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define linkonce_odr i12 @_CG.C.Main.0c4ab795cec6cb27(ptr %self, ptr %t) #0 !dbg !42 {
@@ -332,8 +332,7 @@ fn CallF() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
+// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: read) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/pointer/address_of_field.carbon b/toolchain/lower/testdata/pointer/address_of_field.carbon
index 473c0e44ab3f..236b9889c4f7 100644
--- a/toolchain/lower/testdata/pointer/address_of_field.carbon
+++ b/toolchain/lower/testdata/pointer/address_of_field.carbon
@@ -53,12 +53,11 @@ fn F() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/primitives/numeric_literals.carbon b/toolchain/lower/testdata/primitives/numeric_literals.carbon
index d74af81bd71d..626775682803 100644
--- a/toolchain/lower/testdata/primitives/numeric_literals.carbon
+++ b/toolchain/lower/testdata/primitives/numeric_literals.carbon
@@ -86,8 +86,8 @@ fn F() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
@@ -95,7 +95,6 @@ fn F() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/struct/member_access.carbon b/toolchain/lower/testdata/struct/member_access.carbon
index 2562f739d0eb..3b32c43718e3 100644
--- a/toolchain/lower/testdata/struct/member_access.carbon
+++ b/toolchain/lower/testdata/struct/member_access.carbon
@@ -66,8 +66,8 @@ fn Run() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.7e389eab4a7e5487:core.Destroy.Core", { 1, 0 }
@@ -75,7 +75,6 @@ fn Run() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/struct/two_entries.carbon b/toolchain/lower/testdata/struct/two_entries.carbon
index f59d7ae5fa13..ea6cf259cf99 100644
--- a/toolchain/lower/testdata/struct/two_entries.carbon
+++ b/toolchain/lower/testdata/struct/two_entries.carbon
@@ -59,8 +59,8 @@ fn Run() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.fb32c4dfca65e378:core.Destroy.Core", { 1, 0 }
@@ -68,7 +68,6 @@ fn Run() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/tuple/access/element_access.carbon b/toolchain/lower/testdata/tuple/access/element_access.carbon
index eb7b510acac5..1e75ad8e8a33 100644
--- a/toolchain/lower/testdata/tuple/access/element_access.carbon
+++ b/toolchain/lower/testdata/tuple/access/element_access.carbon
@@ -62,8 +62,8 @@ fn Run() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.7e389eab4a7e5487:core.Destroy.Core", { 1, 0 }
@@ -71,7 +71,6 @@ fn Run() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/tuple/access/return_value_access.carbon b/toolchain/lower/testdata/tuple/access/return_value_access.carbon
index ccb5611d2e94..cb846c67e433 100644
--- a/toolchain/lower/testdata/tuple/access/return_value_access.carbon
+++ b/toolchain/lower/testdata/tuple/access/return_value_access.carbon
@@ -58,18 +58,17 @@ fn Run() {
 // CHECK:STDOUT:   ret void, !dbg !28
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/tuple/two_entries.carbon b/toolchain/lower/testdata/tuple/two_entries.carbon
index 77f8dbc3bd09..4e437a56ee70 100644
--- a/toolchain/lower/testdata/tuple/two_entries.carbon
+++ b/toolchain/lower/testdata/tuple/two_entries.carbon
@@ -59,8 +59,8 @@ fn Run() -> i32 {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @"_COp.8e354c83fe88ab86:core.Destroy.Core", { 1, 0 }
@@ -68,7 +68,6 @@ fn Run() -> i32 {
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/var/global.carbon b/toolchain/lower/testdata/var/global.carbon
index d4bcc07a0192..d975d5999eb4 100644
--- a/toolchain/lower/testdata/var/global.carbon
+++ b/toolchain/lower/testdata/var/global.carbon
@@ -157,14 +157,14 @@ var (_: i32, _: i32) = (3, 4);
 // CHECK:STDOUT:   ret void, !dbg !15
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @_Cd.Main, { 0, 2, 1 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
@@ -202,14 +202,14 @@ var (_: i32, _: i32) = (3, 4);
 // CHECK:STDOUT:   ret void, !dbg !9
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/var/import.carbon b/toolchain/lower/testdata/var/import.carbon
index 89d64112c5ef..2f1efdceff57 100644
--- a/toolchain/lower/testdata/var/import.carbon
+++ b/toolchain/lower/testdata/var/import.carbon
@@ -121,14 +121,14 @@ fn Z() -> i32 { return z; }
 // CHECK:STDOUT:   ret void, !dbg !10
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/var/local.carbon b/toolchain/lower/testdata/var/local.carbon
index 4e5c35d761ba..18300e210b8e 100644
--- a/toolchain/lower/testdata/var/local.carbon
+++ b/toolchain/lower/testdata/var/local.carbon
@@ -125,18 +125,17 @@ fn G() -> (i32, i32, i32) {
 // CHECK:STDOUT:   ret void, !dbg !26
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #2
+// CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
 // CHECK:STDOUT: uselistorder ptr @llvm.memcpy.p0.p0.i64, { 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
-// CHECK:STDOUT: attributes #1 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}
diff --git a/toolchain/lower/testdata/var/param.carbon b/toolchain/lower/testdata/var/param.carbon
index 8a7c7d31111a..d676b50e13ee 100644
--- a/toolchain/lower/testdata/var/param.carbon
+++ b/toolchain/lower/testdata/var/param.carbon
@@ -128,12 +128,11 @@ fn G() {
 // CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 // CHECK:STDOUT: declare void @llvm.lifetime.start.p0(ptr captures(none)) #1
 // CHECK:STDOUT:
-// CHECK:STDOUT: ; Function Attrs: nocallback nofree nounwind willreturn memory(argmem: readwrite)
-// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #2
+// CHECK:STDOUT: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+// CHECK:STDOUT: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg) #1
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
 // CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
-// CHECK:STDOUT: attributes #2 = { nocallback nofree nounwind willreturn memory(argmem: readwrite) }
 // CHECK:STDOUT:
 // CHECK:STDOUT: !llvm.module.flags = !{!0, !1}
 // CHECK:STDOUT: !llvm.dbg.cu = !{!2}