diff --git a/toolchain/lower/function_context.cpp b/toolchain/lower/function_context.cpp
index 273b04574531..0d25e2ad900c 100644
--- a/toolchain/lower/function_context.cpp
+++ b/toolchain/lower/function_context.cpp
@@ -472,6 +472,21 @@ auto FunctionContext::AddTypeToCurrentFingerprint(llvm::Type* type) -> void {
   current_fingerprint_.common_fingerprint.update(os.TakeStr());
 }
 
+auto FunctionContext::AddInstToCurrentFingerprint(SemIR::InstId inst_id)
+    -> void {
+  if (!function_fingerprint_) {
+    return;
+  }
+
+  // TODO: Add some support for fingerprinting spliced instructions so that at
+  // least in easy cases we can deduplicate templates.
+
+  // TODO: Replace indexes with info that is translation unit independent.
+  RawStringOstream os;
+  os << "inst_id" << inst_id.index << "\n";
+  current_fingerprint_.common_fingerprint.update(os.TakeStr());
+}
+
 auto FunctionContext::AddGlobalToCurrentFingerprint(llvm::Value* global)
     -> void {
   if (!function_fingerprint_ || !global) {
diff --git a/toolchain/lower/function_context.h b/toolchain/lower/function_context.h
index e04304475b52..1ee62e34bfb6 100644
--- a/toolchain/lower/function_context.h
+++ b/toolchain/lower/function_context.h
@@ -226,6 +226,10 @@ class FunctionContext {
   // When fingerprinting for a specific, adds the type.
   auto AddTypeToCurrentFingerprint(llvm::Type* type) -> void;
 
+  // When fingerprinting for a specific of a template, adds the given
+  // instruction.
+  auto AddInstToCurrentFingerprint(SemIR::InstId inst_id) -> void;
+
   // Emits the final function fingerprints. Only called when function lowering
   // is complete.
   auto EmitFinalFingerprint() -> void;
diff --git a/toolchain/lower/handle.cpp b/toolchain/lower/handle.cpp
index 71fd95bf334f..33a3516e7d46 100644
--- a/toolchain/lower/handle.cpp
+++ b/toolchain/lower/handle.cpp
@@ -375,6 +375,7 @@ auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
       inst_ir->constant_values().GetInstAs<SemIR::InstValue>(inst_value_id);
   if (inst_ir == &context.sem_ir()) {
     // Easy case: same file. Just emit the spliced instruction.
+    context.AddInstToCurrentFingerprint(inst_value.inst_id);
     context.LowerInst(inst_value.inst_id);
     context.SetLocal(inst_id, context.GetValue(inst_value.inst_id));
   } else {
diff --git a/toolchain/lower/testdata/template/merging.carbon b/toolchain/lower/testdata/template/merging.carbon
new file mode 100644
index 000000000000..f1f3b7b8d72f
--- /dev/null
+++ b/toolchain/lower/testdata/template/merging.carbon
@@ -0,0 +1,509 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/full.carbon
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/template/merging.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/template/merging.carbon
+
+// --- merge_constant.carbon
+library "[[@TEST_NAME]]";
+
+base class A { fn F(); }
+base class B { fn F(); }
+class C { extend base: B; }
+
+fn CallF(template T: type) { T.F(); }
+
+fn CallCallF() {
+  CallF(A);
+  // TODO: It'd be nice to merge these, because they both resolve to calls that
+  // call the same constant callee. But they're splicing different instructions,
+  // so that will take some work.
+  CallF(B);
+  CallF(C);
+}
+
+// --- no_merge_different_conversions.carbon
+library "[[@TEST_NAME]]";
+
+class A { fn F(self); }
+class B { fn F(self); }
+class C {
+  alias F = B.F;
+  impl as Core.ImplicitAs(B) {
+    fn Convert(unused self) -> B { return {}; }
+  }
+}
+class D {
+  alias F = B.F;
+  impl as Core.ImplicitAs(B) {
+    fn Convert(unused self) -> B { return {}; }
+  }
+}
+
+fn InitAndCallF(template T: type) { ({} as T).F(); }
+
+fn CallCallF() {
+  InitAndCallF(A);
+  InitAndCallF(B);
+  InitAndCallF(C);
+  InitAndCallF(D);
+}
+
+fn CallBF[template T: type](x: T) {
+  x.(B.F)();
+}
+
+fn CallCallBF() {
+  CallBF({} as B);
+  CallBF({} as C);
+  CallBF({} as D);
+}
+
+// --- no_merge_convert_one_arg.carbon
+library "[[@TEST_NAME]]";
+
+class A {}
+class B {
+  impl as Core.ImplicitAs(A) {
+    fn Convert(unused self) -> A { return {}; }
+  }
+}
+
+fn F(x: A, y: A);
+
+fn CallF[template T: type, template U: type](x: T, y: U) {
+  F(x, y);
+}
+
+fn CallCallF(a: A, b: B) {
+  CallF(a, a);
+  CallF(a, b);
+  CallF(b, a);
+  CallF(b, b);
+}
+
+// CHECK:STDOUT: ; ---
+// CHECK:STDOUT: ; ModuleID = 'merge_constant.carbon'
+// CHECK:STDOUT: source_filename = "merge_constant.carbon"
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_CF.A.Main()
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_CF.B.Main()
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @_CCallCallF.Main() #0 !dbg !4 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CCallF.Main.bd4fb75a414fe858(), !dbg !7
+// CHECK:STDOUT:   call void @_CCallF.Main.a6a60dfee2d7d273(), !dbg !8
+// CHECK:STDOUT:   call void @_CCallF.Main.9522ff908e97e267(), !dbg !9
+// CHECK:STDOUT:   ret void, !dbg !10
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.bd4fb75a414fe858() #0 !dbg !11 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.A.Main(), !dbg !12
+// CHECK:STDOUT:   ret void, !dbg !13
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.a6a60dfee2d7d273() #0 !dbg !14 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.B.Main(), !dbg !15
+// CHECK:STDOUT:   ret void, !dbg !16
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.9522ff908e97e267() #0 !dbg !17 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.B.Main(), !dbg !18
+// CHECK:STDOUT:   ret void, !dbg !19
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { nounwind }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.dbg.cu = !{!0}
+// CHECK:STDOUT: !llvm.module.flags = !{!2, !3}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !1 = !DIFile(filename: "merge_constant.carbon", directory: "")
+// CHECK:STDOUT: !2 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !3 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "CallCallF", linkageName: "_CCallCallF.Main", scope: null, file: !1, line: 9, type: !5, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
+// CHECK:STDOUT: !6 = !{null}
+// CHECK:STDOUT: !7 = !DILocation(line: 10, column: 3, scope: !4)
+// CHECK:STDOUT: !8 = !DILocation(line: 14, column: 3, scope: !4)
+// CHECK:STDOUT: !9 = !DILocation(line: 15, column: 3, scope: !4)
+// CHECK:STDOUT: !10 = !DILocation(line: 9, column: 1, scope: !4)
+// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.bd4fb75a414fe858", scope: null, file: !1, line: 7, type: !5, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !12 = !DILocation(line: 7, column: 30, scope: !11)
+// CHECK:STDOUT: !13 = !DILocation(line: 7, column: 1, scope: !11)
+// CHECK:STDOUT: !14 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.a6a60dfee2d7d273", scope: null, file: !1, line: 7, type: !5, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !15 = !DILocation(line: 7, column: 30, scope: !14)
+// CHECK:STDOUT: !16 = !DILocation(line: 7, column: 1, scope: !14)
+// CHECK:STDOUT: !17 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.9522ff908e97e267", scope: null, file: !1, line: 7, type: !5, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !18 = !DILocation(line: 7, column: 30, scope: !17)
+// CHECK:STDOUT: !19 = !DILocation(line: 7, column: 1, scope: !17)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; ---
+// CHECK:STDOUT: ; ModuleID = 'no_merge_different_conversions.carbon'
+// CHECK:STDOUT: source_filename = "no_merge_different_conversions.carbon"
+// CHECK:STDOUT:
+// CHECK:STDOUT: @B.val = internal constant {} zeroinitializer
+// CHECK:STDOUT: @C.val = internal constant {} zeroinitializer
+// CHECK:STDOUT: @D.val = internal constant {} zeroinitializer
+// CHECK:STDOUT: @B.val.loc8_45 = internal constant {} zeroinitializer
+// CHECK:STDOUT: @C.val.loc33_13.3 = internal constant {} zeroinitializer
+// CHECK:STDOUT: @D.val.loc34_13.3 = internal constant {} zeroinitializer
+// CHECK:STDOUT: @A.val.A.val = internal constant {} zeroinitializer
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_CF.A.Main(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_CF.B.Main(ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @"_CConvert.C.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr sret({}) %return, ptr %self) #0 !dbg !4 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %return, ptr align 1 @B.val.loc8_45, i64 0, i1 false), !dbg !10
+// CHECK:STDOUT:   ret void, !dbg !10
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @"_CConvert.D.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr sret({}) %return, ptr %self) #0 !dbg !11 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %return, ptr align 1 @B.val.loc8_45, i64 0, i1 false), !dbg !14
+// CHECK:STDOUT:   ret void, !dbg !14
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @_CCallCallF.Main() #0 !dbg !15 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CInitAndCallF.Main.bd4fb75a414fe858(), !dbg !18
+// CHECK:STDOUT:   call void @_CInitAndCallF.Main.a6a60dfee2d7d273(), !dbg !19
+// CHECK:STDOUT:   call void @_CInitAndCallF.Main.9522ff908e97e267(), !dbg !20
+// CHECK:STDOUT:   call void @_CInitAndCallF.Main.931317eeae6ffe17(), !dbg !21
+// CHECK:STDOUT:   ret void, !dbg !22
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @_CCallCallBF.Main() #0 !dbg !23 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.loc32_11.2.temp = alloca {}, align 1, !dbg !24
+// CHECK:STDOUT:   %.loc33_11.2.temp = alloca {}, align 1, !dbg !25
+// CHECK:STDOUT:   %.loc34_11.2.temp = alloca {}, align 1, !dbg !26
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc32_11.2.temp), !dbg !24
+// CHECK:STDOUT:   call void @_CCallBF.Main.a6a60dfee2d7d273(ptr @B.val.loc8_45), !dbg !27
+// CHECK:STDOUT:   call void @"_COp.535580a8a7a96b3b:core.Destroy.Core"(ptr @B.val), !dbg !24
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc33_11.2.temp), !dbg !25
+// CHECK:STDOUT:   call void @_CCallBF.Main.9522ff908e97e267(ptr @C.val.loc33_13.3), !dbg !28
+// CHECK:STDOUT:   call void @"_COp.cbd14a388b4a1c25:core.Destroy.Core"(ptr @C.val), !dbg !25
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.loc34_11.2.temp), !dbg !26
+// CHECK:STDOUT:   call void @_CCallBF.Main.931317eeae6ffe17(ptr @D.val.loc34_13.3), !dbg !29
+// CHECK:STDOUT:   call void @"_COp.86bfabb7802f32e5:core.Destroy.Core"(ptr @D.val), !dbg !26
+// CHECK:STDOUT:   ret void, !dbg !30
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define weak_odr void @"_COp.535580a8a7a96b3b:core.Destroy.Core"(ptr %self) #0 !dbg !31 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   ret void, !dbg !36
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define weak_odr void @"_COp.cbd14a388b4a1c25:core.Destroy.Core"(ptr %self) #0 !dbg !37 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   ret void, !dbg !40
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define weak_odr void @"_COp.86bfabb7802f32e5:core.Destroy.Core"(ptr %self) #0 !dbg !41 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   ret void, !dbg !44
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// 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 @_CInitAndCallF.Main.bd4fb75a414fe858() #0 !dbg !45 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.A.Main(ptr @A.val.A.val), !dbg !46
+// CHECK:STDOUT:   ret void, !dbg !47
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CInitAndCallF.Main.a6a60dfee2d7d273() #0 !dbg !48 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr @B.val.loc8_45), !dbg !49
+// CHECK:STDOUT:   ret void, !dbg !50
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CInitAndCallF.Main.9522ff908e97e267() #0 !dbg !51 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.2a64a1.4.temp = alloca {}, align 1, !dbg !52
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.2a64a1.4.temp), !dbg !52
+// CHECK:STDOUT:   call void @"_CConvert.C.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr %.2a64a1.4.temp, ptr @C.val.loc33_13.3), !dbg !52
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr %.2a64a1.4.temp), !dbg !53
+// CHECK:STDOUT:   ret void, !dbg !54
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CInitAndCallF.Main.931317eeae6ffe17() #0 !dbg !55 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.2a64a1.3.temp = alloca {}, align 1, !dbg !56
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.2a64a1.3.temp), !dbg !56
+// CHECK:STDOUT:   call void @"_CConvert.D.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr %.2a64a1.3.temp, ptr @D.val.loc34_13.3), !dbg !56
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr %.2a64a1.3.temp), !dbg !57
+// CHECK:STDOUT:   ret void, !dbg !58
+// CHECK:STDOUT: }
+// 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:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallBF.Main.a6a60dfee2d7d273(ptr %x) #0 !dbg !59 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr %x), !dbg !62
+// CHECK:STDOUT:   ret void, !dbg !63
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallBF.Main.9522ff908e97e267(ptr %x) #0 !dbg !64 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.2a64a1.2.temp = alloca {}, align 1, !dbg !67
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.2a64a1.2.temp), !dbg !67
+// CHECK:STDOUT:   call void @"_CConvert.C.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr %.2a64a1.2.temp, ptr %x), !dbg !67
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr %.2a64a1.2.temp), !dbg !67
+// CHECK:STDOUT:   ret void, !dbg !68
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallBF.Main.931317eeae6ffe17(ptr %x) #0 !dbg !69 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.2a64a1.1.temp = alloca {}, align 1, !dbg !72
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.2a64a1.1.temp), !dbg !72
+// CHECK:STDOUT:   call void @"_CConvert.D.Main:ImplicitAs.a6a60dfee2d7d273.Core"(ptr %.2a64a1.1.temp, ptr %x), !dbg !72
+// CHECK:STDOUT:   call void @_CF.B.Main(ptr %.2a64a1.1.temp), !dbg !72
+// CHECK:STDOUT:   ret void, !dbg !73
+// CHECK:STDOUT: }
+// 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, { 0, 1, 6, 5, 4, 3, 2 }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { nounwind }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.dbg.cu = !{!0}
+// CHECK:STDOUT: !llvm.module.flags = !{!2, !3}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !1 = !DIFile(filename: "no_merge_different_conversions.carbon", directory: "")
+// CHECK:STDOUT: !2 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !3 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "Convert", linkageName: "_CConvert.C.Main:ImplicitAs.a6a60dfee2d7d273.Core", scope: null, file: !1, line: 8, type: !5, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !8)
+// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
+// CHECK:STDOUT: !6 = !{!7, !7}
+// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+// CHECK:STDOUT: !8 = !{!9}
+// CHECK:STDOUT: !9 = !DILocalVariable(arg: 1, scope: !4, type: !7)
+// CHECK:STDOUT: !10 = !DILocation(line: 8, column: 36, scope: !4)
+// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "Convert", linkageName: "_CConvert.D.Main:ImplicitAs.a6a60dfee2d7d273.Core", scope: null, file: !1, line: 14, type: !5, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !12)
+// CHECK:STDOUT: !12 = !{!13}
+// CHECK:STDOUT: !13 = !DILocalVariable(arg: 1, scope: !11, type: !7)
+// CHECK:STDOUT: !14 = !DILocation(line: 14, column: 36, scope: !11)
+// CHECK:STDOUT: !15 = distinct !DISubprogram(name: "CallCallF", linkageName: "_CCallCallF.Main", scope: null, file: !1, line: 20, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !16 = !DISubroutineType(types: !17)
+// CHECK:STDOUT: !17 = !{null}
+// CHECK:STDOUT: !18 = !DILocation(line: 21, column: 3, scope: !15)
+// CHECK:STDOUT: !19 = !DILocation(line: 22, column: 3, scope: !15)
+// CHECK:STDOUT: !20 = !DILocation(line: 23, column: 3, scope: !15)
+// CHECK:STDOUT: !21 = !DILocation(line: 24, column: 3, scope: !15)
+// CHECK:STDOUT: !22 = !DILocation(line: 20, column: 1, scope: !15)
+// CHECK:STDOUT: !23 = distinct !DISubprogram(name: "CallCallBF", linkageName: "_CCallCallBF.Main", scope: null, file: !1, line: 31, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !24 = !DILocation(line: 32, column: 10, scope: !23)
+// CHECK:STDOUT: !25 = !DILocation(line: 33, column: 10, scope: !23)
+// CHECK:STDOUT: !26 = !DILocation(line: 34, column: 10, scope: !23)
+// CHECK:STDOUT: !27 = !DILocation(line: 32, column: 3, scope: !23)
+// CHECK:STDOUT: !28 = !DILocation(line: 33, column: 3, scope: !23)
+// CHECK:STDOUT: !29 = !DILocation(line: 34, column: 3, scope: !23)
+// CHECK:STDOUT: !30 = !DILocation(line: 31, column: 1, scope: !23)
+// CHECK:STDOUT: !31 = distinct !DISubprogram(name: "Op", linkageName: "_COp.535580a8a7a96b3b:core.Destroy.Core", scope: null, file: !1, line: 32, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !34)
+// CHECK:STDOUT: !32 = !DISubroutineType(types: !33)
+// CHECK:STDOUT: !33 = !{null, !7}
+// CHECK:STDOUT: !34 = !{!35}
+// CHECK:STDOUT: !35 = !DILocalVariable(arg: 1, scope: !31, type: !7)
+// CHECK:STDOUT: !36 = !DILocation(line: 32, column: 10, scope: !31)
+// CHECK:STDOUT: !37 = distinct !DISubprogram(name: "Op", linkageName: "_COp.cbd14a388b4a1c25:core.Destroy.Core", scope: null, file: !1, line: 33, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !38)
+// CHECK:STDOUT: !38 = !{!39}
+// CHECK:STDOUT: !39 = !DILocalVariable(arg: 1, scope: !37, type: !7)
+// CHECK:STDOUT: !40 = !DILocation(line: 33, column: 10, scope: !37)
+// CHECK:STDOUT: !41 = distinct !DISubprogram(name: "Op", linkageName: "_COp.86bfabb7802f32e5:core.Destroy.Core", scope: null, file: !1, line: 34, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !42)
+// CHECK:STDOUT: !42 = !{!43}
+// CHECK:STDOUT: !43 = !DILocalVariable(arg: 1, scope: !41, type: !7)
+// CHECK:STDOUT: !44 = !DILocation(line: 34, column: 10, scope: !41)
+// CHECK:STDOUT: !45 = distinct !DISubprogram(name: "InitAndCallF", linkageName: "_CInitAndCallF.Main.bd4fb75a414fe858", scope: null, file: !1, line: 18, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !46 = !DILocation(line: 18, column: 37, scope: !45)
+// CHECK:STDOUT: !47 = !DILocation(line: 18, column: 1, scope: !45)
+// CHECK:STDOUT: !48 = distinct !DISubprogram(name: "InitAndCallF", linkageName: "_CInitAndCallF.Main.a6a60dfee2d7d273", scope: null, file: !1, line: 18, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !49 = !DILocation(line: 18, column: 37, scope: !48)
+// CHECK:STDOUT: !50 = !DILocation(line: 18, column: 1, scope: !48)
+// CHECK:STDOUT: !51 = distinct !DISubprogram(name: "InitAndCallF", linkageName: "_CInitAndCallF.Main.9522ff908e97e267", scope: null, file: !1, line: 18, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !52 = !DILocation(line: 0, scope: !51)
+// CHECK:STDOUT: !53 = !DILocation(line: 18, column: 37, scope: !51)
+// CHECK:STDOUT: !54 = !DILocation(line: 18, column: 1, scope: !51)
+// CHECK:STDOUT: !55 = distinct !DISubprogram(name: "InitAndCallF", linkageName: "_CInitAndCallF.Main.931317eeae6ffe17", scope: null, file: !1, line: 18, type: !16, spFlags: DISPFlagDefinition, unit: !0)
+// CHECK:STDOUT: !56 = !DILocation(line: 0, scope: !55)
+// CHECK:STDOUT: !57 = !DILocation(line: 18, column: 37, scope: !55)
+// CHECK:STDOUT: !58 = !DILocation(line: 18, column: 1, scope: !55)
+// CHECK:STDOUT: !59 = distinct !DISubprogram(name: "CallBF", linkageName: "_CCallBF.Main.a6a60dfee2d7d273", scope: null, file: !1, line: 27, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !60)
+// CHECK:STDOUT: !60 = !{!61}
+// CHECK:STDOUT: !61 = !DILocalVariable(arg: 1, scope: !59, type: !7)
+// CHECK:STDOUT: !62 = !DILocation(line: 28, column: 3, scope: !59)
+// CHECK:STDOUT: !63 = !DILocation(line: 27, column: 1, scope: !59)
+// CHECK:STDOUT: !64 = distinct !DISubprogram(name: "CallBF", linkageName: "_CCallBF.Main.9522ff908e97e267", scope: null, file: !1, line: 27, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !65)
+// CHECK:STDOUT: !65 = !{!66}
+// CHECK:STDOUT: !66 = !DILocalVariable(arg: 1, scope: !64, type: !7)
+// CHECK:STDOUT: !67 = !DILocation(line: 28, column: 3, scope: !64)
+// CHECK:STDOUT: !68 = !DILocation(line: 27, column: 1, scope: !64)
+// CHECK:STDOUT: !69 = distinct !DISubprogram(name: "CallBF", linkageName: "_CCallBF.Main.931317eeae6ffe17", scope: null, file: !1, line: 27, type: !32, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !70)
+// CHECK:STDOUT: !70 = !{!71}
+// CHECK:STDOUT: !71 = !DILocalVariable(arg: 1, scope: !69, type: !7)
+// CHECK:STDOUT: !72 = !DILocation(line: 28, column: 3, scope: !69)
+// CHECK:STDOUT: !73 = !DILocation(line: 27, column: 1, scope: !69)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; ---
+// CHECK:STDOUT: ; ModuleID = 'no_merge_convert_one_arg.carbon'
+// CHECK:STDOUT: source_filename = "no_merge_convert_one_arg.carbon"
+// CHECK:STDOUT:
+// CHECK:STDOUT: @A.val.loc6_45 = internal constant {} zeroinitializer
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @"_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core"(ptr sret({}) %return, ptr %self) #0 !dbg !4 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @llvm.memcpy.p0.p0.i64(ptr align 1 %return, ptr align 1 @A.val.loc6_45, i64 0, i1 false), !dbg !10
+// CHECK:STDOUT:   ret void, !dbg !10
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: declare void @_CF.Main(ptr, ptr)
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define void @_CCallCallF.Main(ptr %a, ptr %b) #0 !dbg !11 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CCallF.Main.2877a42045e01a3b(ptr %a, ptr %a), !dbg !17
+// CHECK:STDOUT:   call void @_CCallF.Main.d01354a0ad5f3687(ptr %a, ptr %b), !dbg !18
+// CHECK:STDOUT:   call void @_CCallF.Main.37b67b83fe9ed3dd(ptr %b, ptr %a), !dbg !19
+// CHECK:STDOUT:   call void @_CCallF.Main.7096323a0fb88cc3(ptr %b, ptr %b), !dbg !20
+// CHECK:STDOUT:   ret void, !dbg !21
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// 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 @_CCallF.Main.2877a42045e01a3b(ptr %x, ptr %y) #0 !dbg !22 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   call void @_CF.Main(ptr %x, ptr %y), !dbg !26
+// CHECK:STDOUT:   ret void, !dbg !27
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.d01354a0ad5f3687(ptr %x, ptr %y) #0 !dbg !28 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.9745c1.4.temp = alloca {}, align 1, !dbg !32
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.9745c1.4.temp), !dbg !32
+// CHECK:STDOUT:   call void @"_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core"(ptr %.9745c1.4.temp, ptr %y), !dbg !32
+// CHECK:STDOUT:   call void @_CF.Main(ptr %x, ptr %.9745c1.4.temp), !dbg !32
+// CHECK:STDOUT:   ret void, !dbg !33
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.37b67b83fe9ed3dd(ptr %x, ptr %y) #0 !dbg !34 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.9745c1.3.temp = alloca {}, align 1, !dbg !38
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.9745c1.3.temp), !dbg !38
+// CHECK:STDOUT:   call void @"_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core"(ptr %.9745c1.3.temp, ptr %x), !dbg !38
+// CHECK:STDOUT:   call void @_CF.Main(ptr %.9745c1.3.temp, ptr %y), !dbg !38
+// CHECK:STDOUT:   ret void, !dbg !39
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: ; Function Attrs: nounwind
+// CHECK:STDOUT: define linkonce_odr void @_CCallF.Main.7096323a0fb88cc3(ptr %x, ptr %y) #0 !dbg !40 {
+// CHECK:STDOUT: entry:
+// CHECK:STDOUT:   %.9745c1.1.temp = alloca {}, align 1, !dbg !44
+// CHECK:STDOUT:   %.9745c1.2.temp = alloca {}, align 1, !dbg !44
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.9745c1.1.temp), !dbg !44
+// CHECK:STDOUT:   call void @"_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core"(ptr %.9745c1.1.temp, ptr %x), !dbg !44
+// CHECK:STDOUT:   call void @llvm.lifetime.start.p0(ptr %.9745c1.2.temp), !dbg !44
+// CHECK:STDOUT:   call void @"_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core"(ptr %.9745c1.2.temp, ptr %y), !dbg !44
+// CHECK:STDOUT:   call void @_CF.Main(ptr %.9745c1.1.temp, ptr %.9745c1.2.temp), !dbg !44
+// CHECK:STDOUT:   ret void, !dbg !45
+// CHECK:STDOUT: }
+// 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:
+// CHECK:STDOUT: ; uselistorder directives
+// CHECK:STDOUT: uselistorder ptr @llvm.lifetime.start.p0, { 3, 2, 1, 0 }
+// CHECK:STDOUT:
+// CHECK:STDOUT: attributes #0 = { nounwind }
+// CHECK:STDOUT: attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+// CHECK:STDOUT:
+// CHECK:STDOUT: !llvm.dbg.cu = !{!0}
+// CHECK:STDOUT: !llvm.module.flags = !{!2, !3}
+// CHECK:STDOUT:
+// CHECK:STDOUT: !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "carbon", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+// CHECK:STDOUT: !1 = !DIFile(filename: "no_merge_convert_one_arg.carbon", directory: "")
+// CHECK:STDOUT: !2 = !{i32 7, !"Dwarf Version", i32 5}
+// CHECK:STDOUT: !3 = !{i32 2, !"Debug Info Version", i32 3}
+// CHECK:STDOUT: !4 = distinct !DISubprogram(name: "Convert", linkageName: "_CConvert.B.Main:ImplicitAs.bd4fb75a414fe858.Core", scope: null, file: !1, line: 6, type: !5, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !8)
+// CHECK:STDOUT: !5 = !DISubroutineType(types: !6)
+// CHECK:STDOUT: !6 = !{!7, !7}
+// CHECK:STDOUT: !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+// CHECK:STDOUT: !8 = !{!9}
+// CHECK:STDOUT: !9 = !DILocalVariable(arg: 1, scope: !4, type: !7)
+// CHECK:STDOUT: !10 = !DILocation(line: 6, column: 36, scope: !4)
+// CHECK:STDOUT: !11 = distinct !DISubprogram(name: "CallCallF", linkageName: "_CCallCallF.Main", scope: null, file: !1, line: 16, type: !12, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !14)
+// CHECK:STDOUT: !12 = !DISubroutineType(types: !13)
+// CHECK:STDOUT: !13 = !{null, !7, !7}
+// CHECK:STDOUT: !14 = !{!15, !16}
+// CHECK:STDOUT: !15 = !DILocalVariable(arg: 1, scope: !11, type: !7)
+// CHECK:STDOUT: !16 = !DILocalVariable(arg: 2, scope: !11, type: !7)
+// CHECK:STDOUT: !17 = !DILocation(line: 17, column: 3, scope: !11)
+// CHECK:STDOUT: !18 = !DILocation(line: 18, column: 3, scope: !11)
+// CHECK:STDOUT: !19 = !DILocation(line: 19, column: 3, scope: !11)
+// CHECK:STDOUT: !20 = !DILocation(line: 20, column: 3, scope: !11)
+// CHECK:STDOUT: !21 = !DILocation(line: 16, column: 1, scope: !11)
+// CHECK:STDOUT: !22 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.2877a42045e01a3b", scope: null, file: !1, line: 12, type: !12, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !23)
+// CHECK:STDOUT: !23 = !{!24, !25}
+// CHECK:STDOUT: !24 = !DILocalVariable(arg: 1, scope: !22, type: !7)
+// CHECK:STDOUT: !25 = !DILocalVariable(arg: 2, scope: !22, type: !7)
+// CHECK:STDOUT: !26 = !DILocation(line: 13, column: 3, scope: !22)
+// CHECK:STDOUT: !27 = !DILocation(line: 12, column: 1, scope: !22)
+// CHECK:STDOUT: !28 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.d01354a0ad5f3687", scope: null, file: !1, line: 12, type: !12, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !29)
+// CHECK:STDOUT: !29 = !{!30, !31}
+// CHECK:STDOUT: !30 = !DILocalVariable(arg: 1, scope: !28, type: !7)
+// CHECK:STDOUT: !31 = !DILocalVariable(arg: 2, scope: !28, type: !7)
+// CHECK:STDOUT: !32 = !DILocation(line: 13, column: 3, scope: !28)
+// CHECK:STDOUT: !33 = !DILocation(line: 12, column: 1, scope: !28)
+// CHECK:STDOUT: !34 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.37b67b83fe9ed3dd", scope: null, file: !1, line: 12, type: !12, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !35)
+// CHECK:STDOUT: !35 = !{!36, !37}
+// CHECK:STDOUT: !36 = !DILocalVariable(arg: 1, scope: !34, type: !7)
+// CHECK:STDOUT: !37 = !DILocalVariable(arg: 2, scope: !34, type: !7)
+// CHECK:STDOUT: !38 = !DILocation(line: 13, column: 3, scope: !34)
+// CHECK:STDOUT: !39 = !DILocation(line: 12, column: 1, scope: !34)
+// CHECK:STDOUT: !40 = distinct !DISubprogram(name: "CallF", linkageName: "_CCallF.Main.7096323a0fb88cc3", scope: null, file: !1, line: 12, type: !12, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !41)
+// CHECK:STDOUT: !41 = !{!42, !43}
+// CHECK:STDOUT: !42 = !DILocalVariable(arg: 1, scope: !40, type: !7)
+// CHECK:STDOUT: !43 = !DILocalVariable(arg: 2, scope: !40, type: !7)
+// CHECK:STDOUT: !44 = !DILocation(line: 13, column: 3, scope: !40)
+// CHECK:STDOUT: !45 = !DILocation(line: 12, column: 1, scope: !40)
+// CHECK:STDOUT: