diff --git a/toolchain/check/testdata/impl/fail_call_invalid.carbon b/toolchain/check/testdata/impl/fail_call_invalid.carbon
index 6f8faf413313..a8bc6d3d112c 100644
--- a/toolchain/check/testdata/impl/fail_call_invalid.carbon
+++ b/toolchain/check/testdata/impl/fail_call_invalid.carbon
@@ -155,8 +155,7 @@ fn InstanceCall(n: i32) {
 // CHECK:STDOUT: fn @i32.as.Simple.impl.G.loc24_27.2(%self.param: %i32) [thunk @i32.as.Simple.impl.%i32.as.Simple.impl.G.decl.loc24_27.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %G.ref: %i32.as.Simple.impl.G.type.32ad7a.1 = name_ref G, @i32.as.Simple.impl.%i32.as.Simple.impl.G.decl.loc24_27.1 [concrete = constants.%i32.as.Simple.impl.G.4f6260.1]
-// CHECK:STDOUT:   %self.ref: %i32 = name_ref self, %self.param
-// CHECK:STDOUT:   %i32.as.Simple.impl.G.bound: <bound method> = bound_method %self.ref, %G.ref
+// CHECK:STDOUT:   %i32.as.Simple.impl.G.bound: <bound method> = bound_method %self.param, %G.ref
 // CHECK:STDOUT:   %i32.as.Simple.impl.G.call: init %empty_tuple.type = call %i32.as.Simple.impl.G.bound(<error>)
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
diff --git a/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon b/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
index 6f8e1b7291dd..fec34a0b1c84 100644
--- a/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
+++ b/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
@@ -1234,10 +1234,7 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FMissingParam.as.J.impl.F.loc117_31.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FMissingParam.as.J.impl.%FMissingParam.as.J.impl.F.decl.loc117_31.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FMissingParam.as.J.impl.F.type.0f71d8.1 = name_ref F, @FMissingParam.as.J.impl.%FMissingParam.as.J.impl.F.decl.loc117_31.1 [concrete = constants.%FMissingParam.as.J.impl.F.7540f6.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FMissingParam.as.J.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %FMissingParam.as.J.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1246,10 +1243,7 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FMissingImplicitParam.as.J.impl.F.loc130_26.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FMissingImplicitParam.as.J.impl.%FMissingImplicitParam.as.J.impl.F.decl.loc130_26.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FMissingImplicitParam.as.J.impl.F.type.80a56b.1 = name_ref F, @FMissingImplicitParam.as.J.impl.%FMissingImplicitParam.as.J.impl.F.decl.loc130_26.1 [concrete = constants.%FMissingImplicitParam.as.J.impl.F.c6a0b7.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FMissingImplicitParam.as.J.impl.F.call: init bool = call %F.ref(%b.ref)
+// CHECK:STDOUT:   %FMissingImplicitParam.as.J.impl.F.call: init bool = call %F.ref(%b.param)
 // CHECK:STDOUT:   return %FMissingImplicitParam.as.J.impl.F.call
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1258,11 +1252,8 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FMissingReturnType.as.J.impl.F.loc152_30.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FMissingReturnType.as.J.impl.%FMissingReturnType.as.J.impl.F.decl.loc152_30.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FMissingReturnType.as.J.impl.F.type.ce0d21.1 = name_ref F, @FMissingReturnType.as.J.impl.%FMissingReturnType.as.J.impl.F.decl.loc152_30.1 [concrete = constants.%FMissingReturnType.as.J.impl.F.5b613a.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FMissingReturnType.as.J.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %FMissingReturnType.as.J.impl.F.call: init %empty_tuple.type = call %FMissingReturnType.as.J.impl.F.bound(%self.ref, %b.ref)
+// CHECK:STDOUT:   %FMissingReturnType.as.J.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %FMissingReturnType.as.J.impl.F.call: init %empty_tuple.type = call %FMissingReturnType.as.J.impl.F.bound(%self.param, %b.param)
 // CHECK:STDOUT:   %.loc152: bool = converted %FMissingReturnType.as.J.impl.F.call, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
@@ -1272,12 +1263,9 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FDifferentParamType.as.J.impl.F.loc171_38.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FDifferentParamType.as.J.impl.%FDifferentParamType.as.J.impl.F.decl.loc171_38.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FDifferentParamType.as.J.impl.F.type.10926d.1 = name_ref F, @FDifferentParamType.as.J.impl.%FDifferentParamType.as.J.impl.F.decl.loc171_38.1 [concrete = constants.%FDifferentParamType.as.J.impl.F.f1245a.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FDifferentParamType.as.J.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %.loc103: %FDifferentParamType = converted %b.ref, <error> [concrete = <error>]
-// CHECK:STDOUT:   %FDifferentParamType.as.J.impl.F.call: init bool = call %FDifferentParamType.as.J.impl.F.bound(%self.ref, <error>)
+// CHECK:STDOUT:   %FDifferentParamType.as.J.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %.loc103: %FDifferentParamType = converted %b.param, <error> [concrete = <error>]
+// CHECK:STDOUT:   %FDifferentParamType.as.J.impl.F.call: init bool = call %FDifferentParamType.as.J.impl.F.bound(%self.param, <error>)
 // CHECK:STDOUT:   return %FDifferentParamType.as.J.impl.F.call
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1286,12 +1274,9 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FDifferentImplicitParamType.as.J.impl.F.loc184_38.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FDifferentImplicitParamType.as.J.impl.%FDifferentImplicitParamType.as.J.impl.F.decl.loc184_38.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FDifferentImplicitParamType.as.J.impl.F.type.955391.1 = name_ref F, @FDifferentImplicitParamType.as.J.impl.%FDifferentImplicitParamType.as.J.impl.F.decl.loc184_38.1 [concrete = constants.%FDifferentImplicitParamType.as.J.impl.F.a9ece4.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FDifferentImplicitParamType.as.J.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %.loc103: %FDifferentImplicitParamType = converted %self.ref, <error> [concrete = <error>]
-// CHECK:STDOUT:   %FDifferentImplicitParamType.as.J.impl.F.call: init bool = call %FDifferentImplicitParamType.as.J.impl.F.bound(<error>, %b.ref)
+// CHECK:STDOUT:   %FDifferentImplicitParamType.as.J.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %.loc103: %FDifferentImplicitParamType = converted %self.param, <error> [concrete = <error>]
+// CHECK:STDOUT:   %FDifferentImplicitParamType.as.J.impl.F.call: init bool = call %FDifferentImplicitParamType.as.J.impl.F.bound(<error>, %b.param)
 // CHECK:STDOUT:   return %FDifferentImplicitParamType.as.J.impl.F.call
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1300,12 +1285,9 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @FDifferentReturnType.as.J.impl.F.loc200_38.2(%self.param: bool, %b.param: bool) -> out %return.param: bool [thunk @FDifferentReturnType.as.J.impl.%FDifferentReturnType.as.J.impl.F.decl.loc200_38.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %FDifferentReturnType.as.J.impl.F.type.7bcb67.1 = name_ref F, @FDifferentReturnType.as.J.impl.%FDifferentReturnType.as.J.impl.F.decl.loc200_38.1 [concrete = constants.%FDifferentReturnType.as.J.impl.F.a709b1.1]
-// CHECK:STDOUT:   %self.ref: bool = name_ref self, %self.param
-// CHECK:STDOUT:   %b.ref: bool = name_ref b, %b.param
-// CHECK:STDOUT:   %return.ref: ref bool = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %FDifferentReturnType.as.J.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %FDifferentReturnType.as.J.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   %.loc200_38.1: ref %FDifferentReturnType = temporary_storage
-// CHECK:STDOUT:   %FDifferentReturnType.as.J.impl.F.call: init %FDifferentReturnType to %.loc200_38.1 = call %FDifferentReturnType.as.J.impl.F.bound(%self.ref, %b.ref)
+// CHECK:STDOUT:   %FDifferentReturnType.as.J.impl.F.call: init %FDifferentReturnType to %.loc200_38.1 = call %FDifferentReturnType.as.J.impl.F.bound(%self.param, %b.param)
 // CHECK:STDOUT:   %.loc200_38.2: bool = converted %FDifferentReturnType.as.J.impl.F.call, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
@@ -1330,11 +1312,9 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @SelfNestedBadParam.as.SelfNested.impl.F.loc223_87.2(%x.param: %tuple.type.7ea) -> out %return.param: %array_type.388 [thunk @SelfNestedBadParam.as.SelfNested.impl.%SelfNestedBadParam.as.SelfNested.impl.F.decl.loc223_87.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %SelfNestedBadParam.as.SelfNested.impl.F.type.789632.1 = name_ref F, @SelfNestedBadParam.as.SelfNested.impl.%SelfNestedBadParam.as.SelfNested.impl.F.decl.loc223_87.1 [concrete = constants.%SelfNestedBadParam.as.SelfNested.impl.F.6e1661.1]
-// CHECK:STDOUT:   %x.ref: %tuple.type.7ea = name_ref x, %x.param
-// CHECK:STDOUT:   %return.ref: ref %array_type.388 = name_ref <return slot>, %return.param
 // CHECK:STDOUT:   %.loc211_57: ref %array_type.388 = splice_block %return.param {}
-// CHECK:STDOUT:   %tuple.elem0: %ptr.cf2 = tuple_access %x.ref, element0
-// CHECK:STDOUT:   %tuple.elem1: %struct_type.x.y.62a = tuple_access %x.ref, element1
+// CHECK:STDOUT:   %tuple.elem0: %ptr.cf2 = tuple_access %x.param, element0
+// CHECK:STDOUT:   %tuple.elem1: %struct_type.x.y.62a = tuple_access %x.param, element1
 // CHECK:STDOUT:   %.loc211_9.1: %SelfNestedBadParam = struct_access %tuple.elem1, element0
 // CHECK:STDOUT:   %.loc211_9.2: %i32 = converted %.loc211_9.1, <error> [concrete = <error>]
 // CHECK:STDOUT:   %SelfNestedBadParam.as.SelfNested.impl.F.call: init %array_type.388 to %.loc211_57 = call %F.ref(<error>)
@@ -1346,10 +1326,8 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT: fn @SelfNestedBadReturnType.as.SelfNested.impl.F.loc239_112.2(%x.param: %tuple.type.064) -> out %return.param: %array_type.31b [thunk @SelfNestedBadReturnType.as.SelfNested.impl.%SelfNestedBadReturnType.as.SelfNested.impl.F.decl.loc239_112.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %SelfNestedBadReturnType.as.SelfNested.impl.F.type.75d128.1 = name_ref F, @SelfNestedBadReturnType.as.SelfNested.impl.%SelfNestedBadReturnType.as.SelfNested.impl.F.decl.loc239_112.1 [concrete = constants.%SelfNestedBadReturnType.as.SelfNested.impl.F.587f77.1]
-// CHECK:STDOUT:   %x.ref: %tuple.type.064 = name_ref x, %x.param
-// CHECK:STDOUT:   %return.ref: ref %array_type.31b = name_ref <return slot>, %return.param
 // CHECK:STDOUT:   %.loc239_112.1: ref %array_type.388 = temporary_storage
-// CHECK:STDOUT:   %SelfNestedBadReturnType.as.SelfNested.impl.F.call: init %array_type.388 to %.loc239_112.1 = call %F.ref(%x.ref)
+// CHECK:STDOUT:   %SelfNestedBadReturnType.as.SelfNested.impl.F.call: init %array_type.388 to %.loc239_112.1 = call %F.ref(%x.param)
 // CHECK:STDOUT:   %.loc239_112.2: %array_type.31b = converted %SelfNestedBadReturnType.as.SelfNested.impl.F.call, <error> [concrete = <error>]
 // CHECK:STDOUT:   return <error> to %return.param
 // CHECK:STDOUT: }
diff --git a/toolchain/check/testdata/impl/fail_self_type_mismatch.carbon b/toolchain/check/testdata/impl/fail_self_type_mismatch.carbon
index 06e4918d7ac2..dcc8de012d33 100644
--- a/toolchain/check/testdata/impl/fail_self_type_mismatch.carbon
+++ b/toolchain/check/testdata/impl/fail_self_type_mismatch.carbon
@@ -258,8 +258,7 @@ impl i32 as I {
 // CHECK:STDOUT: fn @i32.as.I.impl.F.loc43_18.2(%c.param: %C.719) [thunk @i32.as.I.impl.%i32.as.I.impl.F.decl.loc43_18.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %i32.as.I.impl.F.type.6c53e7.1 = name_ref F, @i32.as.I.impl.%i32.as.I.impl.F.decl.loc43_18.1 [concrete = constants.%i32.as.I.impl.F.7f652f.1]
-// CHECK:STDOUT:   %c.ref: %C.719 = name_ref c, %c.param
-// CHECK:STDOUT:   %.loc25: %C.899 = converted %c.ref, <error> [concrete = <error>]
+// CHECK:STDOUT:   %.loc25: %C.899 = converted %c.param, <error> [concrete = <error>]
 // CHECK:STDOUT:   %i32.as.I.impl.F.call: init %empty_tuple.type = call %F.ref(<error>)
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
diff --git a/toolchain/check/testdata/impl/impl_thunk.carbon b/toolchain/check/testdata/impl/impl_thunk.carbon
index 796594aa29cc..c192132d52e6 100644
--- a/toolchain/check/testdata/impl/impl_thunk.carbon
+++ b/toolchain/check/testdata/impl/impl_thunk.carbon
@@ -389,7 +389,6 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @empty_tuple.type.as.I.impl.F.loc10_48.2(%x.param: %struct_type.a.b.391) -> out %return.param: %struct_type.c.d.15a [thunk @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_48.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %empty_tuple.type.as.I.impl.F.type.19e4b8.1 = name_ref F, @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_48.1 [concrete = constants.%empty_tuple.type.as.I.impl.F.8be29b.1]
-// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %.loc10_48.1: ref %struct_type.d.c.b36 = temporary_storage
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %empty_tuple.type.as.I.impl.F.call: init %struct_type.d.c.b36 to %.loc10_48.1 = call %F.ref(%.loc5_9.3)
@@ -490,8 +489,7 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @B.as.X.impl.F.loc14_37.2(%self.param: ref %B, %other.param: %ptr.27c) -> out %return.param: %ptr.27c [thunk @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %B.as.X.impl.F.type.421a66.1 = name_ref F, @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1 [concrete = constants.%B.as.X.impl.F.8ec460.1]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %B.as.X.impl.F.call: init %ptr.31e = call %B.as.X.impl.F.bound(%.loc9_16.2, %.loc9_29.3)
 // CHECK:STDOUT:   %.loc14_37.1: %ptr.31e = value_of_initializer %B.as.X.impl.F.call
@@ -553,8 +551,7 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @B.as.X.impl.F.loc13_26.2(%self.param: %B, %other.param: %B) [thunk @B.as.X.impl.%B.as.X.impl.F.decl.loc13_26.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %B.as.X.impl.F.type.421a66.1 = name_ref F, @B.as.X.impl.%B.as.X.impl.F.decl.loc13_26.1 [concrete = constants.%B.as.X.impl.F.8ec460.1]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %B.as.X.impl.F.call: init %empty_tuple.type = call %B.as.X.impl.F.bound(%.loc8_12.3, %.loc8_25.3)
 // CHECK:STDOUT:   return
@@ -639,8 +636,7 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @B.as.X.impl.F.loc14_37.2(%self.param: ref %B, %other.param: %ptr.27c) -> out %return.param: %ptr.27c [thunk @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %B.as.X.impl.F.type.421a66.1 = name_ref F, @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1 [concrete = constants.%B.as.X.impl.F.8ec460.1]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %B.as.X.impl.F.call: init %ptr.31e = call %B.as.X.impl.F.bound(%.loc9_16.2, %.loc9_29.3)
 // CHECK:STDOUT:   %.loc14_37.1: %ptr.31e = value_of_initializer %B.as.X.impl.F.call
@@ -736,8 +732,7 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @B.as.X.impl.F.loc14_37.2(%self.param: ref %B, %other.param: %ptr.27c) -> out %return.param: %ptr.27c [thunk @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %B.as.X.impl.F.type.421a66.1 = name_ref F, @B.as.X.impl.%B.as.X.impl.F.decl.loc14_37.1 [concrete = constants.%B.as.X.impl.F.8ec460.1]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:   %B.as.X.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %B.as.X.impl.F.call: init %ptr.31e = call %B.as.X.impl.F.bound(%.loc9_16.2, %.loc9_29.3)
 // CHECK:STDOUT:   %.loc14_37.1: %ptr.31e = value_of_initializer %B.as.X.impl.F.call
@@ -799,7 +794,6 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @A.as.X.impl.F.loc23_14.2() -> out %return.param: %A [thunk @A.as.X.impl.%A.as.X.impl.F.decl.loc23_14.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %A.as.X.impl.F.type.170a02.1 = name_ref F, @A.as.X.impl.%A.as.X.impl.F.decl.loc23_14.1 [concrete = constants.%A.as.X.impl.F.e6cf46.1]
-// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %.loc23_14.1: ref %B = temporary_storage
 // CHECK:STDOUT:   %A.as.X.impl.F.call: init %B to %.loc23_14.1 = call %F.ref()
 // CHECK:STDOUT:   %.loc23_14.2: ref %B = temporary %.loc23_14.1, %A.as.X.impl.F.call
@@ -937,11 +931,10 @@ impl () as I({}) {
 // CHECK:STDOUT:   fn(%x.param: @empty_tuple.type.as.I.impl.F.loc10_34.2.%ptr (%ptr.e8f)) -> out %return.param: @empty_tuple.type.as.I.impl.F.loc10_34.2.%ptr (%ptr.e8f) [thunk @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_34.1] {
 // CHECK:STDOUT:   !entry:
 // CHECK:STDOUT:     %F.ref: %empty_tuple.type.as.I.impl.F.type.19e4b8.1 = name_ref F, @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_34.1 [concrete = constants.%empty_tuple.type.as.I.impl.F.8be29b.1]
-// CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:     %Copy.facet.loc10_34.1: %Copy.type = facet_value constants.%ptr.e8f, (constants.%Copy.lookup_impl_witness.2e6) [symbolic = %Copy.facet.loc10_34.2 (constants.%Copy.facet)]
 // CHECK:STDOUT:     %.loc10_34.1: %Copy.type = converted constants.%ptr.e8f, %Copy.facet.loc10_34.1 [symbolic = %Copy.facet.loc10_34.2 (constants.%Copy.facet)]
 // CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.specific_fn.loc10_34.1: <specific function> = specific_function %F.ref, @empty_tuple.type.as.I.impl.F.loc10_34.1(constants.%Copy.facet) [symbolic = %empty_tuple.type.as.I.impl.F.specific_fn.loc10_34.2 (constants.%empty_tuple.type.as.I.impl.F.specific_fn)]
-// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.call: init @empty_tuple.type.as.I.impl.F.loc10_34.2.%ptr (%ptr.e8f) = call %empty_tuple.type.as.I.impl.F.specific_fn.loc10_34.1(%x.ref)
+// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.call: init @empty_tuple.type.as.I.impl.F.loc10_34.2.%ptr (%ptr.e8f) = call %empty_tuple.type.as.I.impl.F.specific_fn.loc10_34.1(%x.param)
 // CHECK:STDOUT:     return %empty_tuple.type.as.I.impl.F.call
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
@@ -1110,13 +1103,12 @@ impl () as I({}) {
 // CHECK:STDOUT:   fn(%self.param: %empty_tuple.type, %x.param: @empty_tuple.type.as.I.impl.F.loc10_51.2.%ptr (%ptr.e8f)) -> out %return.param: @empty_tuple.type.as.I.impl.F.loc10_51.2.%ptr (%ptr.e8f) [thunk @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_51.1] {
 // CHECK:STDOUT:   !entry:
 // CHECK:STDOUT:     %F.ref: %empty_tuple.type.as.I.impl.F.type.19e4b8.1 = name_ref F, @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_51.1 [concrete = constants.%empty_tuple.type.as.I.impl.F.8be29b.1]
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
+// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
 // CHECK:STDOUT:     %Copy.facet.loc10_51.1: %Copy.type = facet_value constants.%ptr.e8f, (constants.%Copy.lookup_impl_witness.2e6) [symbolic = %Copy.facet.loc10_51.2 (constants.%Copy.facet)]
 // CHECK:STDOUT:     %.loc10_51.1: %Copy.type = converted constants.%ptr.e8f, %Copy.facet.loc10_51.1 [symbolic = %Copy.facet.loc10_51.2 (constants.%Copy.facet)]
 // CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.specific_fn.loc10_51.1: <specific function> = specific_function %F.ref, @empty_tuple.type.as.I.impl.F.loc10_51.1(constants.%Copy.facet) [symbolic = %empty_tuple.type.as.I.impl.F.specific_fn.loc10_51.2 (constants.%empty_tuple.type.as.I.impl.F.specific_fn)]
-// CHECK:STDOUT:     %bound_method: <bound method> = bound_method %self.ref, %empty_tuple.type.as.I.impl.F.specific_fn.loc10_51.1
-// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.call: init @empty_tuple.type.as.I.impl.F.loc10_51.2.%ptr (%ptr.e8f) = call %bound_method(%self.ref, %x.ref)
+// CHECK:STDOUT:     %bound_method: <bound method> = bound_method %self.param, %empty_tuple.type.as.I.impl.F.specific_fn.loc10_51.1
+// CHECK:STDOUT:     %empty_tuple.type.as.I.impl.F.call: init @empty_tuple.type.as.I.impl.F.loc10_51.2.%ptr (%ptr.e8f) = call %bound_method(%self.param, %x.param)
 // CHECK:STDOUT:     return %empty_tuple.type.as.I.impl.F.call
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
@@ -1201,7 +1193,6 @@ impl () as I({}) {
 // CHECK:STDOUT: fn @empty_tuple.type.as.I.impl.F.loc10_29.2() -> out %return.param: %struct_type.a.b.f95 [thunk @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_29.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %empty_tuple.type.as.I.impl.F.type.e82c13.1 = name_ref F, @empty_tuple.type.as.I.impl.%empty_tuple.type.as.I.impl.F.decl.loc10_29.1 [concrete = constants.%empty_tuple.type.as.I.impl.F.5f0cef.1]
-// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %.loc10_29.1: ref %struct_type.b.a.1b0 = temporary_storage
 // CHECK:STDOUT:   %empty_tuple.type.as.I.impl.F.call: init %struct_type.b.a.1b0 to %.loc10_29.1 = call %F.ref()
 // CHECK:STDOUT:   %.loc10_29.2: ref %struct_type.b.a.1b0 = temporary %.loc10_29.1, %empty_tuple.type.as.I.impl.F.call
diff --git a/toolchain/check/testdata/impl/import_thunk.carbon b/toolchain/check/testdata/impl/import_thunk.carbon
index 8ac1aee12a51..e6e298873235 100644
--- a/toolchain/check/testdata/impl/import_thunk.carbon
+++ b/toolchain/check/testdata/impl/import_thunk.carbon
@@ -305,11 +305,10 @@ fn G() {
 // CHECK:STDOUT:   !entry:
 // CHECK:STDOUT:     %.loc8: @C.as.I.impl.F.loc8_24.2.%C.as.I.impl.F.type (%C.as.I.impl.F.type.cf838e.1) = specific_constant @C.as.I.impl.%C.as.I.impl.F.decl.loc8_24.1, @C.as.I.impl(constants.%Y) [symbolic = %C.as.I.impl.F (constants.%C.as.I.impl.F.421e41.1)]
 // CHECK:STDOUT:     %F.ref: @C.as.I.impl.F.loc8_24.2.%C.as.I.impl.F.type (%C.as.I.impl.F.type.cf838e.1) = name_ref F, %.loc8 [symbolic = %C.as.I.impl.F (constants.%C.as.I.impl.F.421e41.1)]
-// CHECK:STDOUT:     %x.ref: %empty_struct_type = name_ref x, %x.param
 // CHECK:STDOUT:     %C.as.I.impl.F.specific_fn.loc8_24.1: <specific function> = specific_function %F.ref, @C.as.I.impl.F.loc8_24.1(constants.%Y) [symbolic = %C.as.I.impl.F.specific_fn.loc8_24.2 (constants.%C.as.I.impl.F.specific_fn)]
 // CHECK:STDOUT:     %.1: ref @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) = temporary_storage
 // CHECK:STDOUT:     %.2: init @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) to %.1 = class_init () [symbolic = %C.val (constants.%C.val)]
-// CHECK:STDOUT:     %.3: init @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) = converted %x.ref, %.2 [symbolic = %C.val (constants.%C.val)]
+// CHECK:STDOUT:     %.3: init @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) = converted %x.param, %.2 [symbolic = %C.val (constants.%C.val)]
 // CHECK:STDOUT:     %.4: ref @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) = temporary %.1, %.3
 // CHECK:STDOUT:     %.5: @C.as.I.impl.F.loc8_24.2.%C (%C.c8540f.2) = acquire_value %.4
 // CHECK:STDOUT:     %C.as.I.impl.F.call: init %empty_tuple.type = call %C.as.I.impl.F.specific_fn.loc8_24.1(%.5)
diff --git a/toolchain/check/testdata/impl/use_assoc_entity.carbon b/toolchain/check/testdata/impl/use_assoc_entity.carbon
index 3efbf7606b6b..2ce08c6430b4 100644
--- a/toolchain/check/testdata/impl/use_assoc_entity.carbon
+++ b/toolchain/check/testdata/impl/use_assoc_entity.carbon
@@ -2728,8 +2728,6 @@ fn F() {
 // CHECK:STDOUT: fn @E.as.J.impl.F.loc27_21.2(%u.param: %i32) -> out %return.param: %i32 [thunk @E.as.J.impl.%E.as.J.impl.F.decl.loc27_21.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %E.as.J.impl.F.type.4b5c2a.1 = name_ref F, @E.as.J.impl.%E.as.J.impl.F.decl.loc27_21.1 [concrete = constants.%E.as.J.impl.F.b4e6ab.1]
-// CHECK:STDOUT:   %u.ref: %i32 = name_ref u, %u.param
-// CHECK:STDOUT:   %return.ref: ref %i32 = name_ref <return slot>, %return.param
 // CHECK:STDOUT:   %E.as.J.impl.F.call: <error> = call %F.ref(<error>)
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
@@ -3449,9 +3447,8 @@ fn F() {
 // CHECK:STDOUT: fn @empty_tuple.type.as.J2.impl.F.loc23_40.2(%self.param: %empty_tuple.type) -> <error> [thunk @empty_tuple.type.as.J2.impl.%empty_tuple.type.as.J2.impl.F.decl.loc23_40.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %empty_tuple.type.as.J2.impl.F.type.56bdaf.1 = name_ref F, @empty_tuple.type.as.J2.impl.%empty_tuple.type.as.J2.impl.F.decl.loc23_40.1 [concrete = constants.%empty_tuple.type.as.J2.impl.F.7b8679.1]
-// CHECK:STDOUT:   %self.ref: %empty_tuple.type = name_ref self, %self.param
-// CHECK:STDOUT:   %empty_tuple.type.as.J2.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %empty_tuple.type.as.J2.impl.F.call: init %empty_struct_type = call %empty_tuple.type.as.J2.impl.F.bound(%self.ref, <error>)
+// CHECK:STDOUT:   %empty_tuple.type.as.J2.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %empty_tuple.type.as.J2.impl.F.call: init %empty_struct_type = call %empty_tuple.type.as.J2.impl.F.bound(%self.param, <error>)
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -3468,9 +3465,8 @@ fn F() {
 // CHECK:STDOUT: fn @C2.as.J2.impl.F.loc32_40.2(%self.param: %C2) -> <error> [thunk @C2.as.J2.impl.%C2.as.J2.impl.F.decl.loc32_40.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %C2.as.J2.impl.F.type.d2a210.1 = name_ref F, @C2.as.J2.impl.%C2.as.J2.impl.F.decl.loc32_40.1 [concrete = constants.%C2.as.J2.impl.F.720bb2.1]
-// CHECK:STDOUT:   %self.ref: %C2 = name_ref self, %self.param
-// CHECK:STDOUT:   %C2.as.J2.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %C2.as.J2.impl.F.call: init %C2 = call %C2.as.J2.impl.F.bound(%self.ref, <error>)
+// CHECK:STDOUT:   %C2.as.J2.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %C2.as.J2.impl.F.call: init %C2 = call %C2.as.J2.impl.F.bound(%self.param, <error>)
 // CHECK:STDOUT:   return <error>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -3726,11 +3722,8 @@ fn F() {
 // CHECK:STDOUT: fn @empty_tuple.type.as.K.impl.F.loc26_52.2(%self.param: %empty_tuple.type, %v.param: %struct_type.a) -> out %return.param: %struct_type.a [thunk @empty_tuple.type.as.K.impl.%empty_tuple.type.as.K.impl.F.decl.loc26_52.1] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %F.ref: %empty_tuple.type.as.K.impl.F.type.1710d5.1 = name_ref F, @empty_tuple.type.as.K.impl.%empty_tuple.type.as.K.impl.F.decl.loc26_52.1 [concrete = constants.%empty_tuple.type.as.K.impl.F.907e52.1]
-// CHECK:STDOUT:   %self.ref: %empty_tuple.type = name_ref self, %self.param
-// CHECK:STDOUT:   %v.ref: %struct_type.a = name_ref v, %v.param
-// CHECK:STDOUT:   %return.ref: ref %struct_type.a = name_ref <return slot>, %return.param
-// CHECK:STDOUT:   %empty_tuple.type.as.K.impl.F.bound: <bound method> = bound_method %self.ref, %F.ref
-// CHECK:STDOUT:   %empty_tuple.type.as.K.impl.F.call: init %struct_type.x = call %empty_tuple.type.as.K.impl.F.bound(%self.ref, <error>)
+// CHECK:STDOUT:   %empty_tuple.type.as.K.impl.F.bound: <bound method> = bound_method %self.param, %F.ref
+// CHECK:STDOUT:   %empty_tuple.type.as.K.impl.F.call: init %struct_type.x = call %empty_tuple.type.as.K.impl.F.bound(%self.param, <error>)
 // CHECK:STDOUT:   %.loc26_52.1: ref %struct_type.x = temporary_storage
 // CHECK:STDOUT:   %.loc26_52.2: ref %struct_type.x = temporary %.loc26_52.1, %empty_tuple.type.as.K.impl.F.call
 // CHECK:STDOUT:   %Destroy.Op.bound: <bound method> = bound_method %.loc26_52.2, constants.%Destroy.Op
diff --git a/toolchain/check/testdata/interop/cpp/function/default_arg.carbon b/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
index 2e456f8a6ab6..594e923ba301 100644
--- a/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/default_arg.carbon
@@ -847,9 +847,8 @@ fn Call() {
 // CHECK:STDOUT: fn @X.Op(%self.param: ref %X) [thunk imports.%X.cpp_destructor.decl] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Op.ref: %X.cpp_destructor.type = name_ref Op, imports.%X.cpp_destructor.decl [concrete = constants.%X.cpp_destructor]
-// CHECK:STDOUT:   %self.ref: ref %X = name_ref self, %self.param
-// CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %self.ref, %Op.ref
-// CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%self.ref)
+// CHECK:STDOUT:   %X.cpp_destructor.bound: <bound method> = bound_method %self.param, %Op.ref
+// CHECK:STDOUT:   %X.cpp_destructor.call: init %empty_tuple.type = call %X.cpp_destructor.bound(%self.param)
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/impls/destroy.carbon b/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
index 661cecc07709..a5154a032b61 100644
--- a/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
+++ b/toolchain/check/testdata/interop/cpp/impls/destroy.carbon
@@ -324,9 +324,8 @@ fn EqualWitnesses(p: Wrap(Cpp.PublicDestructor)*) -> Wrap(Cpp.PublicDestructor)*
 // CHECK:STDOUT: fn @TrivialDestructor.Op(%self.param: ref %TrivialDestructor) [thunk imports.%TrivialDestructor.cpp_destructor.decl] {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Op.ref: %TrivialDestructor.cpp_destructor.type = name_ref Op, imports.%TrivialDestructor.cpp_destructor.decl [concrete = constants.%TrivialDestructor.cpp_destructor]
-// CHECK:STDOUT:   %self.ref: ref %TrivialDestructor = name_ref self, %self.param
-// CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.bound: <bound method> = bound_method %self.ref, %Op.ref
-// CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.call: init %empty_tuple.type = call %TrivialDestructor.cpp_destructor.bound(%self.ref)
+// CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.bound: <bound method> = bound_method %self.param, %Op.ref
+// CHECK:STDOUT:   %TrivialDestructor.cpp_destructor.call: init %empty_tuple.type = call %TrivialDestructor.cpp_destructor.bound(%self.param)
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/thunk.cpp b/toolchain/check/thunk.cpp
index 8089e3a5d2ae..d6eceb5a7f58 100644
--- a/toolchain/check/thunk.cpp
+++ b/toolchain/check/thunk.cpp
@@ -350,21 +350,8 @@ static auto BuildThunkCall(Context& context, SemIR::FunctionId function_id,
   callee_id = BuildNameRef(context, loc_id, function.name_id, callee_id,
                            callee_type.specific_id);
 
-  // Build a reference to each parameter for use as call arguments.
-  llvm::SmallVector<SemIR::InstId> call_args;
   auto call_params = context.inst_blocks().Get(function.call_params_id);
-  call_args.reserve(call_params.size());
-  for (auto call_param_id : call_params) {
-    // Use a pretty name for the `name_ref`. While it's suspicious to use a
-    // pretty name in the IR like this, the only reason we include a name at all
-    // here is to make the formatted SemIR more readable.
-    auto call_param = context.insts().GetAs<SemIR::AnyParam>(call_param_id);
-    call_args.push_back(BuildNameRef(context, SemIR::LocId(call_param_id),
-                                     call_param.pretty_name_id, call_param_id,
-                                     SemIR::SpecificId::None));
-  }
-
-  return PerformThunkCall(context, loc_id, function_id, call_args, callee_id);
+  return PerformThunkCall(context, loc_id, function_id, call_params, callee_id);
 }
 
 // Given a declaration of a thunk and the function that it should call, build