diff --git a/toolchain/check/cpp/import.cpp b/toolchain/check/cpp/import.cpp
index 52a854f62ee1..4fa8bbf1f044 100644
--- a/toolchain/check/cpp/import.cpp
+++ b/toolchain/check/cpp/import.cpp
@@ -1479,6 +1479,19 @@ static auto ImportFunctionDecl(Context& context, SemIR::LocId loc_id,
     // instantiation if needed.
     context.clang_sema().MarkFunctionReferenced(GetCppLocation(context, loc_id),
                                                 clang_decl);
+
+    // If the function is trivial, mark it as being a builtin if possible.
+    if (clang_decl->isTrivial()) {
+      // Trivial destructors map to a "no_op" builtin.
+      if (isa<clang::CXXDestructorDecl>(clang_decl)) {
+        function_info.SetBuiltinFunction(SemIR::BuiltinFunctionKind::NoOp);
+      }
+      // TODO: Should we model a trivial default constructor as performing
+      // value-initialization (zero-initializing all fields) or
+      // default-initialization (leaving fields uniniitalized)? Either way we
+      // could model that effect as a builtin.
+      // TODO: Add a builtin to model trivial copies.
+    }
   }
 
   return function_info.first_owning_decl_id;
diff --git a/toolchain/check/testdata/interop/cpp/function/default_arg.carbon b/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
index bc39c038ef22..cb1e22b3a1be 100644
--- a/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
@@ -807,7 +807,7 @@ fn Call() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @DestroyOp(%self.param: %X) = "no_op";
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @X.cpp_destructor(%self.param: %X);
+// CHECK:STDOUT: fn @X.cpp_destructor(%self.param: %X) = "no_op";
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_call_too_few_args.carbon
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/impls/destroy.carbon b/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
index 92e7733cbaa0..c42ccb3c4dcf 100644
--- a/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
+++ b/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
@@ -53,16 +53,16 @@ library "[[@TEST_NAME]]";
 
 import Cpp library "types.h";
 
+// Dump the whole file so we can see that the trivial destructor maps to a
+// "no_op" builtin.
+//@include-in-dumps
+
 fn PublicDestroy() {
-  //@dump-sem-ir-begin
   var a: Cpp.PublicDestructor = {};
-  //@dump-sem-ir-end
 }
 
 fn TrivialDestroy() {
-  //@dump-sem-ir-begin
   var a: Cpp.TrivialDestructor = {};
-  //@dump-sem-ir-end
 }
 
 // --- destroy_protected_base_destructor.carbon
@@ -181,14 +181,20 @@ fn EqualWitnesses(p: Wrap(Cpp.PublicDestructor)*) -> Wrap(Cpp.PublicDestructor)*
 // CHECK:STDOUT: --- destroy_destroyable.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %PublicDestroy.type: type = fn_type @PublicDestroy [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %PublicDestroy: %PublicDestroy.type = struct_value () [concrete]
 // CHECK:STDOUT:   %PublicDestructor: type = class_type @PublicDestructor [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete]
 // CHECK:STDOUT:   %pattern_type.27d: type = pattern_type %PublicDestructor [concrete]
 // CHECK:STDOUT:   %empty_struct: %empty_struct_type = struct_value () [concrete]
 // CHECK:STDOUT:   %PublicDestructor.val: %PublicDestructor = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor.type: type = fn_type @PublicDestructor.cpp_destructor [concrete]
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor: %PublicDestructor.cpp_destructor.type = struct_value () [concrete]
+// CHECK:STDOUT:   %TrivialDestroy.type: type = fn_type @TrivialDestroy [concrete]
+// CHECK:STDOUT:   %TrivialDestroy: %TrivialDestroy.type = struct_value () [concrete]
 // CHECK:STDOUT:   %TrivialDestructor: type = class_type @TrivialDestructor [concrete]
 // CHECK:STDOUT:   %pattern_type.1b8: type = pattern_type %TrivialDestructor [concrete]
 // CHECK:STDOUT:   %TrivialDestructor.val: %TrivialDestructor = struct_value () [concrete]
@@ -197,15 +203,54 @@ fn EqualWitnesses(p: Wrap(Cpp.PublicDestructor)*) -> Wrap(Cpp.PublicDestructor)*
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
+// CHECK:STDOUT:     .Destroy = %Core.Destroy
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/...
+// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .PublicDestructor = %PublicDestructor.decl
 // CHECK:STDOUT:     .TrivialDestructor = %TrivialDestructor.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %PublicDestructor.decl: type = class_decl @PublicDestructor [concrete = constants.%PublicDestructor] {} {}
+// CHECK:STDOUT:   %Core.Destroy: type = import_ref Core//prelude/parts/destroy, Destroy, loaded [concrete = constants.%Destroy.type]
 // CHECK:STDOUT:   %TrivialDestructor.decl: type = class_decl @TrivialDestructor [concrete = constants.%TrivialDestructor] {} {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .Cpp = imports.%Cpp
+// CHECK:STDOUT:     .PublicDestroy = %PublicDestroy.decl
+// CHECK:STDOUT:     .TrivialDestroy = %TrivialDestroy.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
+// CHECK:STDOUT:     import Cpp "types.h"
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %PublicDestroy.decl: %PublicDestroy.type = fn_decl @PublicDestroy [concrete = constants.%PublicDestroy] {} {}
+// CHECK:STDOUT:   %TrivialDestroy.decl: %TrivialDestroy.type = fn_decl @TrivialDestroy [concrete = constants.%TrivialDestroy] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @PublicDestructor {
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type]
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   import Cpp//...
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @TrivialDestructor {
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
+// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type]
+// CHECK:STDOUT:   complete_type_witness = %complete_type
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   import Cpp//...
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @PublicDestroy() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   name_binding_decl {
@@ -213,21 +258,23 @@ fn EqualWitnesses(p: Wrap(Cpp.PublicDestructor)*) -> Wrap(Cpp.PublicDestructor)*
 // CHECK:STDOUT:     %a.var_patt: %pattern_type.27d = var_pattern %a.patt [concrete]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %a.var: ref %PublicDestructor = var %a.var_patt
-// CHECK:STDOUT:   %.loc8_34.1: %empty_struct_type = struct_literal () [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %.loc8_34.2: init %PublicDestructor = class_init (), %a.var [concrete = constants.%PublicDestructor.val]
-// CHECK:STDOUT:   %.loc8_3: init %PublicDestructor = converted %.loc8_34.1, %.loc8_34.2 [concrete = constants.%PublicDestructor.val]
-// CHECK:STDOUT:   assign %a.var, %.loc8_3
-// CHECK:STDOUT:   %.loc8_13: type = splice_block %PublicDestructor.ref [concrete = constants.%PublicDestructor] {
+// CHECK:STDOUT:   %.loc11_34.1: %empty_struct_type = struct_literal () [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %.loc11_34.2: init %PublicDestructor = class_init (), %a.var [concrete = constants.%PublicDestructor.val]
+// CHECK:STDOUT:   %.loc11_3: init %PublicDestructor = converted %.loc11_34.1, %.loc11_34.2 [concrete = constants.%PublicDestructor.val]
+// CHECK:STDOUT:   assign %a.var, %.loc11_3
+// CHECK:STDOUT:   %.loc11_13: type = splice_block %PublicDestructor.ref [concrete = constants.%PublicDestructor] {
 // CHECK:STDOUT:     %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:     %PublicDestructor.ref: type = name_ref PublicDestructor, imports.%PublicDestructor.decl [concrete = constants.%PublicDestructor]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %a: ref %PublicDestructor = ref_binding a, %a.var
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor.bound: <bound method> = bound_method %a.var, constants.%PublicDestructor.cpp_destructor
 // CHECK:STDOUT:   %PublicDestructor.cpp_destructor.call: init %empty_tuple.type = call %PublicDestructor.cpp_destructor.bound(%a.var)
-// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @DestroyOp.loc8(%self.param: %PublicDestructor) = "no_op";
+// CHECK:STDOUT: fn @DestroyOp.loc11(%self.param: %PublicDestructor) = "no_op";
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @PublicDestructor.cpp_destructor(%self.param: %PublicDestructor);
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @TrivialDestroy() {
 // CHECK:STDOUT: !entry:
@@ -236,21 +283,23 @@ fn EqualWitnesses(p: Wrap(Cpp.PublicDestructor)*) -> Wrap(Cpp.PublicDestructor)*
 // CHECK:STDOUT:     %a.var_patt: %pattern_type.1b8 = var_pattern %a.patt [concrete]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %a.var: ref %TrivialDestructor = var %a.var_patt
-// CHECK:STDOUT:   %.loc14_35.1: %empty_struct_type = struct_literal () [concrete = constants.%empty_struct]
-// CHECK:STDOUT:   %.loc14_35.2: init %TrivialDestructor = class_init (), %a.var [concrete = constants.%TrivialDestructor.val]
-// CHECK:STDOUT:   %.loc14_3: init %TrivialDestructor = converted %.loc14_35.1, %.loc14_35.2 [concrete = constants.%TrivialDestructor.val]
-// CHECK:STDOUT:   assign %a.var, %.loc14_3
-// CHECK:STDOUT:   %.loc14_13: type = splice_block %TrivialDestructor.ref [concrete = constants.%TrivialDestructor] {
+// CHECK:STDOUT:   %.loc15_35.1: %empty_struct_type = struct_literal () [concrete = constants.%empty_struct]
+// CHECK:STDOUT:   %.loc15_35.2: init %TrivialDestructor = class_init (), %a.var [concrete = constants.%TrivialDestructor.val]
+// CHECK:STDOUT:   %.loc15_3: init %TrivialDestructor = converted %.loc15_35.1, %.loc15_35.2 [concrete = constants.%TrivialDestructor.val]
+// CHECK:STDOUT:   assign %a.var, %.loc15_3
+// CHECK:STDOUT:   %.loc15_13: type = splice_block %TrivialDestructor.ref [concrete = constants.%TrivialDestructor] {
 // CHECK:STDOUT:     %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:     %TrivialDestructor.ref: type = name_ref TrivialDestructor, imports.%TrivialDestructor.decl [concrete = constants.%TrivialDestructor]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %a: ref %TrivialDestructor = ref_binding a, %a.var
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.bound: <bound method> = bound_method %a.var, constants.%TrivialDestructor.cpp_destructor
 // CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.call: init %empty_tuple.type = call %TrivialDestructor.cpp_destructor.bound(%a.var)
-// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @DestroyOp.loc14(%self.param: %TrivialDestructor) = "no_op";
+// CHECK:STDOUT: fn @DestroyOp.loc15(%self.param: %TrivialDestructor) = "no_op";
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @TrivialDestructor.cpp_destructor(%self.param: %TrivialDestructor) = "no_op";
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- destroy_protected_base_destructor.carbon
 // CHECK:STDOUT:
diff --git a/toolchain/lower/testdata/interop/cpp/constructor.carbon b/toolchain/lower/testdata/interop/cpp/constructor.carbon
index e29037f715a0..5cd2a46ef58a 100644
--- a/toolchain/lower/testdata/interop/cpp/constructor.carbon
+++ b/toolchain/lower/testdata/interop/cpp/constructor.carbon
@@ -77,12 +77,9 @@ fn Copy(c: Cpp.Copy) -> Cpp.Copy {
 // CHECK:STDOUT:   %.loc7_26.1.temp = alloca [8 x i8], align 1, !dbg !10
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc7_26.1.temp), !dbg !10
 // CHECK:STDOUT:   call void @_ZN1CC1Ev.carbon_thunk(ptr %.loc7_26.1.temp), !dbg !10
-// CHECK:STDOUT:   call void @_ZN1CD1Ev(ptr %.loc7_26.1.temp), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !11
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1CD1Ev(ptr)
-// 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)) #1
 // CHECK:STDOUT:
diff --git a/toolchain/lower/testdata/interop/cpp/parameters.carbon b/toolchain/lower/testdata/interop/cpp/parameters.carbon
index 185afc7023d5..5bc873ac2284 100644
--- a/toolchain/lower/testdata/interop/cpp/parameters.carbon
+++ b/toolchain/lower/testdata/interop/cpp/parameters.carbon
@@ -288,12 +288,9 @@ fn PassValueExpr(y: Cpp.Y) {
 // CHECK:STDOUT:   %.loc10_4.c = getelementptr inbounds nuw [12 x i8], ptr %x.var, i32 0, i32 8, !dbg !13
 // CHECK:STDOUT:   store i32 3, ptr %.loc10_4.c, align 4, !dbg !13
 // CHECK:STDOUT:   call void @_Z11pass_struct1X.carbon_thunk(ptr %x.var), !dbg !14
-// CHECK:STDOUT:   call void @_ZN1XD1Ev(ptr %x.var), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !15
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1XD1Ev(ptr)
-// 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)) #1
 // CHECK:STDOUT:
@@ -367,12 +364,9 @@ fn PassValueExpr(y: Cpp.Y) {
 // CHECK:STDOUT:   %.loc10_4.c = getelementptr inbounds nuw [12 x i8], ptr %y.var, i32 0, i32 8, !dbg !13
 // CHECK:STDOUT:   store i32 3, ptr %.loc10_4.c, align 4, !dbg !13
 // CHECK:STDOUT:   call void @_Z11pass_struct1Y.carbon_thunk(ptr %y.var), !dbg !14
-// CHECK:STDOUT:   call void @_ZN1YD1Ev(ptr %y.var), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !15
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1YD1Ev(ptr)
-// CHECK:STDOUT:
 // CHECK:STDOUT: declare void @_CMake.Main(ptr sret([12 x i8]))
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
@@ -382,7 +376,6 @@ fn PassValueExpr(y: Cpp.Y) {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc17_24.1.temp), !dbg !17
 // CHECK:STDOUT:   call void @_CMake.Main(ptr %.loc17_24.1.temp), !dbg !17
 // CHECK:STDOUT:   call void @_Z11pass_struct1Y.carbon_thunk(ptr %.loc17_24.1.temp), !dbg !18
-// CHECK:STDOUT:   call void @_ZN1YD1Ev(ptr %.loc17_24.1.temp), !dbg !17
 // CHECK:STDOUT:   ret void, !dbg !19
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/lower/testdata/interop/cpp/reference.carbon b/toolchain/lower/testdata/interop/cpp/reference.carbon
index ba2c760327cb..dcf92c4d78c2 100644
--- a/toolchain/lower/testdata/interop/cpp/reference.carbon
+++ b/toolchain/lower/testdata/interop/cpp/reference.carbon
@@ -158,8 +158,6 @@ fn GetRefs() {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc25_23.2.temp), !dbg !14
 // CHECK:STDOUT:   store i32 %.loc25_23.1, ptr %.loc25_23.2.temp, align 4, !dbg !14
 // CHECK:STDOUT:   call void @_Z15TakeConstIntRefRKi.carbon_thunk(ptr %.loc25_23.2.temp), !dbg !20
-// CHECK:STDOUT:   call void @_ZN1CD1Ev(ptr %.loc19_18.2.temp), !dbg !11
-// CHECK:STDOUT:   call void @_ZN1CD1Ev(ptr %c.var), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !21
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -167,8 +165,6 @@ fn GetRefs() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: declare void @_Z10TakeIntRefRi(ptr)
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1CD1Ev(ptr)
-// 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)) #1
 // CHECK:STDOUT:
@@ -224,7 +220,6 @@ fn GetRefs() {
 // CHECK:STDOUT: declare void @_Z15TakeConstIntRefRKi(ptr nonnull align 4 dereferenceable(4)) #4
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
-// CHECK:STDOUT: uselistorder ptr @_ZN1CD1Ev, { 1, 0 }
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 4, 3, 2, 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
@@ -290,13 +285,9 @@ fn GetRefs() {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc26_23.2.temp), !dbg !14
 // CHECK:STDOUT:   store i32 %.loc26_23.1, ptr %.loc26_23.2.temp, align 4, !dbg !14
 // CHECK:STDOUT:   call void @_Z15TakeConstIntRefRKi10ForceThunk.carbon_thunk1(ptr %.loc26_23.2.temp), !dbg !20
-// CHECK:STDOUT:   call void @_ZN1CD1Ev(ptr %.loc20_18.2.temp), !dbg !11
-// CHECK:STDOUT:   call void @_ZN1CD1Ev(ptr %c.var), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !21
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1CD1Ev(ptr)
-// 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)) #1
 // CHECK:STDOUT:
@@ -382,7 +373,6 @@ fn GetRefs() {
 // CHECK:STDOUT: declare void @_Z15TakeConstIntRefRKi10ForceThunk(ptr nonnull align 4 dereferenceable(4)) #4
 // CHECK:STDOUT:
 // CHECK:STDOUT: ; uselistorder directives
-// CHECK:STDOUT: uselistorder ptr @_ZN1CD1Ev, { 1, 0 }
 // CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 4, 3, 2, 1, 0 }
 // CHECK:STDOUT:
 // CHECK:STDOUT: attributes #0 = { nounwind }
diff --git a/toolchain/lower/testdata/interop/cpp/template.carbon b/toolchain/lower/testdata/interop/cpp/template.carbon
index 6f352b081dfa..187d75bfbf93 100644
--- a/toolchain/lower/testdata/interop/cpp/template.carbon
+++ b/toolchain/lower/testdata/interop/cpp/template.carbon
@@ -242,12 +242,9 @@ fn Call3() {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc12_12.2.temp), !dbg !10
 // CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc12_12.2.temp, ptr align 1 @X.val.loc12_12.3, i64 0, i1 false), !dbg !10
 // CHECK:STDOUT:   call void @_Z3fooIJEEv1XDpT_.carbon_thunk(ptr %.loc12_12.2.temp), !dbg !11
-// CHECK:STDOUT:   call void @_ZN1XD1Ev(ptr %.loc12_12.2.temp), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !12
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1XD1Ev(ptr)
-// CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define void @_CCall2.Main() #0 !dbg !13 {
 // CHECK:STDOUT: entry:
@@ -255,7 +252,6 @@ fn Call3() {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc18_12.2.temp), !dbg !14
 // CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc18_12.2.temp, ptr align 1 @X.val.loc12_12.3, i64 0, i1 false), !dbg !14
 // CHECK:STDOUT:   call void @_Z3fooIJiEEv1XDpT_.carbon_thunk(ptr %.loc18_12.2.temp, i32 2), !dbg !15
-// CHECK:STDOUT:   call void @_ZN1XD1Ev(ptr %.loc18_12.2.temp), !dbg !14
 // CHECK:STDOUT:   ret void, !dbg !16
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -266,7 +262,6 @@ fn Call3() {
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc24_12.2.temp), !dbg !18
 // CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %.loc24_12.2.temp, ptr align 1 @X.val.loc12_12.3, i64 0, i1 false), !dbg !18
 // CHECK:STDOUT:   call void @_Z3fooIJiiEEv1XDpT_.carbon_thunk(ptr %.loc24_12.2.temp, i32 2, i32 3), !dbg !19
-// CHECK:STDOUT:   call void @_ZN1XD1Ev(ptr %.loc24_12.2.temp), !dbg !18
 // CHECK:STDOUT:   ret void, !dbg !20
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/lower/testdata/interop/cpp/virtual_base.carbon b/toolchain/lower/testdata/interop/cpp/virtual_base.carbon
index 257125755c89..83ff4e3b4c5e 100644
--- a/toolchain/lower/testdata/interop/cpp/virtual_base.carbon
+++ b/toolchain/lower/testdata/interop/cpp/virtual_base.carbon
@@ -114,12 +114,9 @@ fn AccessD(d: Cpp.D) -> i32 {
 // CHECK:STDOUT:   %_.var = alloca [40 x i8], align 1, !dbg !10
 // CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %_.var), !dbg !10
 // CHECK:STDOUT:   call void @_ZN1DC1Ev.carbon_thunk(ptr %_.var), !dbg !11
-// CHECK:STDOUT:   call void @_ZN1DD1Ev(ptr %_.var), !dbg !10
 // CHECK:STDOUT:   ret void, !dbg !12
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: declare void @_ZN1DD1Ev(ptr)
-// CHECK:STDOUT:
 // CHECK:STDOUT: ; Function Attrs: nounwind
 // CHECK:STDOUT: define i32 @_CAccessD.Main(ptr %d) #0 !dbg !13 {
 // CHECK:STDOUT: entry: