diff --git a/common/ostream.h b/common/ostream.h
index aa82f7436589..b01d393f2afb 100644
--- a/common/ostream.h
+++ b/common/ostream.h
@@ -6,6 +6,7 @@
 #define CARBON_COMMON_OSTREAM_H_
 
 #include <ostream>
+#include <type_traits>
 
 #include "llvm/Support/raw_os_ostream.h"
 // Libraries should include this header instead of raw_ostream.
@@ -50,6 +51,15 @@ class Printable {
   }
 };
 
+// Returns the result of printing the value.
+template <typename T>
+inline auto PrintToString(const T& val) -> std::string {
+  std::string str;
+  llvm::raw_string_ostream stream(str);
+  stream << val;
+  return str;
+}
+
 }  // namespace Carbon
 
 namespace llvm {
diff --git a/toolchain/base/BUILD b/toolchain/base/BUILD
index 34ed65e62c7f..dbd3a85d4eb1 100644
--- a/toolchain/base/BUILD
+++ b/toolchain/base/BUILD
@@ -28,6 +28,7 @@ cc_library(
     hdrs = ["value_store.h"],
     deps = [
         ":index_base",
+        ":yaml",
         "//common:check",
         "//common:ostream",
         "@llvm-project//llvm:Support",
@@ -46,3 +47,13 @@ cc_test(
         "@com_google_googletest//:gtest",
     ],
 )
+
+cc_library(
+    name = "yaml",
+    hdrs = ["yaml.h"],
+    deps = [
+        "//common:check",
+        "//common:ostream",
+        "@llvm-project//llvm:Support",
+    ],
+)
diff --git a/toolchain/base/value_store.h b/toolchain/base/value_store.h
index 2572af2a953f..56621951db54 100644
--- a/toolchain/base/value_store.h
+++ b/toolchain/base/value_store.h
@@ -12,10 +12,12 @@
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
+#include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/YAMLParser.h"
 #include "toolchain/base/index_base.h"
+#include "toolchain/base/yaml.h"
 
 namespace Carbon {
 
@@ -86,73 +88,14 @@ namespace Internal {
 // Used as a parent class for non-printable types. This is just for
 // std::conditional, not as an API.
 class ValueStoreNotPrintable {};
-
-// Provides YAML printing of a value.
-template <typename ValueT>
-inline auto PrintValue(llvm::raw_ostream& out, const ValueT& val) {
-  out << val;
-};
-inline auto PrintValue(llvm::raw_ostream& out, const llvm::APInt& val) {
-  val.print(out, /*isSigned=*/false);
-};
-inline auto PrintValue(llvm::raw_ostream& out, const llvm::StringRef& val) {
-  out << "\"" << llvm::yaml::escape(val) << "\"";
-};
-
-struct DefaultPrinter {
-  template <typename ValueT>
-  void operator()(llvm::raw_ostream& out, const ValueT& value) {
-    PrintValue(out, value);
-  }
-};
-
 }  // namespace Internal
 
-// Provides YAML printing of a list. The first line indent applies even if there
-// is no label, in which case it applies to the first element.
-template <typename ValueT>
-inline auto PrintValueRange(
-    llvm::raw_ostream& out, llvm::iterator_range<const ValueT*> range,
-    std::optional<llvm::StringRef> label, int first_line_indent,
-    int later_indent, bool trailing_newline,
-    llvm::function_ref<void(llvm::raw_ostream&, const ValueT& val)> print =
-        Internal::DefaultPrinter()) {
-  out.indent(first_line_indent);
-  if (label) {
-    out << *label << ":";
-    if (range.empty()) {
-      // Add a space between the `:` and the `[]` printed below.
-      out << " ";
-    } else {
-      out << "\n";
-      out.indent(later_indent);
-    }
-  }
-  if (range.empty()) {
-    out << "[]";
-    if (trailing_newline) {
-      out << "\n";
-    }
-    return;
-  }
-  std::string sep_str = "\n";
-  sep_str.append(later_indent, ' ');
-  llvm::ListSeparator sep(sep_str);
-  for (const auto& val : range) {
-    out << sep << "- ";
-    print(out, val);
-  }
-  if (trailing_newline) {
-    out << "\n";
-  }
-}
-
 // A simple wrapper for accumulating values, providing IDs to later retrieve the
 // value. This does not do deduplication.
 template <typename IdT, typename ValueT = typename IdT::IndexedType>
 class ValueStore
     : public std::conditional<std::is_base_of_v<Printable<ValueT>, ValueT>,
-                              Printable<ValueStore<IdT, ValueT>>,
+                              Yaml::Printable<ValueStore<IdT, ValueT>>,
                               Internal::ValueStoreNotPrintable> {
  public:
   using PrintFn =
@@ -189,17 +132,13 @@ class ValueStore
   auto Reserve(size_t size) -> void { values_.reserve(size); }
 
   // These are to support printable structures, and are not guaranteed.
-  auto Print(llvm::raw_ostream& out) const -> void {
-    Print(out, std::nullopt, 0, 0);
-  }
-  auto Print(llvm::raw_ostream& out, std::optional<llvm::StringRef> label,
-             int first_line_indent, int later_indent,
-             // This decays so that `const llvm::APInt` printing catches the
-             // specialization.
-             PrintFn print = Internal::DefaultPrinter()) const -> void {
-    PrintValueRange(out, llvm::iterator_range(values_), label,
-                    first_line_indent, later_indent, /*trailing_newline=*/true,
-                    print);
+  auto OutputYaml() const -> Yaml::OutputMapping {
+    return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+      for (auto i : llvm::seq(values_.size())) {
+        auto id = IdT(i);
+        map.Add(PrintToString(id), Yaml::OutputScalar(Get(id)));
+      }
+    });
   }
 
   auto array_ref() const -> llvm::ArrayRef<ValueT> { return values_; }
@@ -212,7 +151,7 @@ class ValueStore
 // Storage for StringRefs. The caller is responsible for ensuring storage is
 // allocated.
 template <>
-class ValueStore<StringId> : public Printable<ValueStore<StringId>> {
+class ValueStore<StringId> : public Yaml::Printable<ValueStore<StringId>> {
  public:
   using PrintFn =
       llvm::function_ref<void(llvm::raw_ostream&, const llvm::StringRef& val)>;
@@ -234,15 +173,12 @@ class ValueStore<StringId> : public Printable<ValueStore<StringId>> {
     return values_[id.index];
   }
 
-  auto Print(llvm::raw_ostream& out) const -> void {
-    Print(out, std::nullopt, 0, 0);
-  }
-  auto Print(llvm::raw_ostream& out, std::optional<llvm::StringRef> label,
-             int first_line_indent, int later_indent,
-             PrintFn print = Internal::DefaultPrinter()) const -> void {
-    PrintValueRange(out, llvm::iterator_range(values_), label,
-                    first_line_indent, later_indent, /*trailing_newline=*/true,
-                    print);
+  auto OutputYaml() const -> Yaml::OutputMapping {
+    return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+      for (auto [i, val] : llvm::enumerate(values_)) {
+        map.Add(PrintToString(StringId(i)), val);
+      }
+    });
   }
 
  private:
@@ -252,7 +188,7 @@ class ValueStore<StringId> : public Printable<ValueStore<StringId>> {
 
 // Stores that will be used across compiler steps. This is provided mainly so
 // that they don't need to be passed separately.
-class SharedValueStores : public Printable<SharedValueStores> {
+class SharedValueStores : public Yaml::Printable<SharedValueStores> {
  public:
   auto integers() -> ValueStore<IntegerId>& { return integers_; }
   auto integers() const -> const ValueStore<IntegerId>& { return integers_; }
@@ -261,12 +197,15 @@ class SharedValueStores : public Printable<SharedValueStores> {
   auto strings() -> ValueStore<StringId>& { return strings_; }
   auto strings() const -> const ValueStore<StringId>& { return strings_; }
 
-  auto Print(llvm::raw_ostream& out) const -> void {
-    out << "shared_values:\n"
-        << "  - ";
-    integers_.Print(out, "integers", 0, 6);
-    reals_.Print(out, "reals", 4, 6);
-    strings_.Print(out, "strings", 4, 6);
+  auto OutputYaml() const -> Yaml::OutputMapping {
+    return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+      map.Add("shared_values",
+              Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+                map.Add("integers", integers_.OutputYaml());
+                map.Add("reals", reals_.OutputYaml());
+                map.Add("strings", strings_.OutputYaml());
+              }));
+    });
   }
 
  private:
diff --git a/toolchain/base/value_store_test.cpp b/toolchain/base/value_store_test.cpp
index d248ae7d3273..c0bb41c4011f 100644
--- a/toolchain/base/value_store_test.cpp
+++ b/toolchain/base/value_store_test.cpp
@@ -78,14 +78,14 @@ TEST(ValueStore, String) {
   EXPECT_THAT(value_stores.strings().Add(b), Eq(b_id));
 }
 
-auto MatchSharedValues(testing::Matcher<Yaml::SequenceValue> integers,
-                       testing::Matcher<Yaml::SequenceValue> reals,
-                       testing::Matcher<Yaml::SequenceValue> strings) -> auto {
+auto MatchSharedValues(testing::Matcher<Yaml::MappingValue> integers,
+                       testing::Matcher<Yaml::MappingValue> reals,
+                       testing::Matcher<Yaml::MappingValue> strings) -> auto {
   return Yaml::IsYaml(Yaml::Sequence(ElementsAre(Yaml::Mapping(ElementsAre(Pair(
-      "shared_values", Yaml::Sequence(ElementsAre(Yaml::Mapping(ElementsAre(
-                           Pair("integers", Yaml::Sequence(integers)),
-                           Pair("reals", Yaml::Sequence(reals)),
-                           Pair("strings", Yaml::Sequence(strings))))))))))));
+      "shared_values",
+      Yaml::Mapping(ElementsAre(Pair("integers", Yaml::Mapping(integers)),
+                                Pair("reals", Yaml::Mapping(reals)),
+                                Pair("strings", Yaml::Mapping(strings))))))))));
 }
 
 TEST(ValueStore, PrintEmpty) {
@@ -106,10 +106,11 @@ TEST(ValueStore, PrintVals) {
   TestRawOstream out;
   value_stores.Print(out);
 
-  EXPECT_THAT(Yaml::Value::FromText(out.TakeStr()),
-              MatchSharedValues(ElementsAre(Yaml::Scalar("8")),
-                                ElementsAre(Yaml::Scalar("8*10^8")),
-                                ElementsAre(Yaml::Scalar("foo'\"baz"))));
+  EXPECT_THAT(
+      Yaml::Value::FromText(out.TakeStr()),
+      MatchSharedValues(ElementsAre(Pair("int0", Yaml::Scalar("8"))),
+                        ElementsAre(Pair("real0", Yaml::Scalar("8*10^8"))),
+                        ElementsAre(Pair("str0", Yaml::Scalar("foo'\"baz")))));
 }
 
 }  // namespace
diff --git a/toolchain/base/yaml.h b/toolchain/base/yaml.h
new file mode 100644
index 000000000000..86496836a4d9
--- /dev/null
+++ b/toolchain/base/yaml.h
@@ -0,0 +1,115 @@
+// 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
+
+#ifndef CARBON_TOOLCHAIN_BASE_YAML_H_
+#define CARBON_TOOLCHAIN_BASE_YAML_H_
+
+#include "common/check.h"
+#include "common/ostream.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/YAMLTraits.h"
+
+// This file provides adapters for outputting YAML using llvm::yaml's APIs. It
+// only supports output, not input. However, it addresses the mix of const and
+// non-const expectations of the llvm::yaml that make it difficult to otherwise
+// use the trait-based approach.
+
+namespace Carbon::Yaml {
+
+// Helper for printing YAML, to maintain a consistent configuration.
+template <typename T>
+inline auto Print(llvm::raw_ostream& out, T yaml) -> void {
+  llvm::yaml::Output yout(out, /*Ctxt=*/nullptr, /*WrapColumn=*/80);
+  yout << yaml;
+}
+
+// Similar to the standard Printable<T>, but relies on OutputYaml for printing.
+template <typename T>
+class Printable : public Carbon::Printable<T> {
+ public:
+  auto Print(llvm::raw_ostream& out) const -> void {
+    Carbon::Yaml::Print(out, static_cast<const T*>(this)->OutputYaml());
+  }
+};
+
+// Adapts a function for outputting YAML as a scalar. This currently assumes no
+// scalars passed through this should be quoted.
+class OutputScalar {
+ public:
+  template <typename T>
+  explicit OutputScalar(const T& val)
+      : output_([&](llvm::raw_ostream& out) -> void { out << val; }) {}
+
+  explicit OutputScalar(const llvm::APInt& val)
+      : output_([&](llvm::raw_ostream& out) -> void {
+          // Carbon's plain APInt storage is typically unsigned.
+          val.print(out, /*isSigned=*/false);
+        }) {}
+
+  explicit OutputScalar(std::function<void(llvm::raw_ostream&)> output)
+      : output_(std::move(output)) {}
+
+  auto Output(llvm::raw_ostream& out) const -> void { output_(out); }
+
+ private:
+  std::function<void(llvm::raw_ostream&)> output_;
+};
+
+// Adapts a function for outputting YAML as a mapping.
+class OutputMapping {
+ public:
+  class Map {
+   public:
+    explicit Map(llvm::yaml::IO& io) : io_(io) {}
+
+    // Maps a value. This mainly takes responsibility for copying the value,
+    // letting mapRequired take `&value`.
+    template <typename T>
+    auto Add(llvm::StringRef key, T value) -> void {
+      io_.mapRequired(key.data(), value);
+    }
+
+   private:
+    llvm::yaml::IO& io_;
+  };
+
+  explicit OutputMapping(std::function<void(OutputMapping::Map)> output)
+      : output_(std::move(output)) {}
+
+  auto Output(llvm::yaml::IO& io) -> void { output_(Map(io)); }
+
+ private:
+  std::function<void(OutputMapping::Map)> output_;
+};
+
+}  // namespace Carbon::Yaml
+
+// Link OutputScalar to the llvm::yaml::IO API.
+template <>
+struct llvm::yaml::ScalarTraits<Carbon::Yaml::OutputScalar> {
+  static auto output(const Carbon::Yaml::OutputScalar& value, void* /*ctxt*/,
+                     llvm::raw_ostream& out) -> void {
+    value.Output(out);
+  }
+  static auto input(StringRef /*scalar*/, void* /*ctxt*/,
+                    Carbon::Yaml::OutputScalar& /*value*/) -> StringRef {
+    CARBON_FATAL() << "Input is unsupported.";
+  }
+  static auto mustQuote(StringRef /*value*/) -> QuotingType {
+    return QuotingType::None;
+  }
+};
+static_assert(llvm::yaml::has_ScalarTraits<Carbon::Yaml::OutputScalar>::value);
+
+// Link OutputMapping to the llvm::yaml::IO API.
+template <>
+struct llvm::yaml::MappingTraits<Carbon::Yaml::OutputMapping> {
+  static auto mapping(IO& io, Carbon::Yaml::OutputMapping& mapping) -> void {
+    mapping.Output(io);
+  }
+};
+static_assert(llvm::yaml::has_MappingTraits<Carbon::Yaml::OutputMapping,
+                                            llvm::yaml::EmptyContext>::value);
+
+#endif  // CARBON_TOOLCHAIN_BASE_YAML_H_
diff --git a/toolchain/check/testdata/basics/builtin_nodes.carbon b/toolchain/check/testdata/basics/builtin_nodes.carbon
index b6453ecb8c4e..2e12bacb06bc 100644
--- a/toolchain/check/testdata/basics/builtin_nodes.carbon
+++ b/toolchain/check/testdata/basics/builtin_nodes.carbon
@@ -6,21 +6,23 @@
 //
 // AUTOUPDATE
 
-// CHECK:STDOUT: - filename: builtin_nodes.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions: []
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types: []
-// CHECK:STDOUT:     type_blocks: []
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeTypeType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeError, type: typeError}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeBoolType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeIntegerType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeFloatingPointType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeStringType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeFunctionType, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: CrossReference, arg0: ir0, arg1: nodeNamespaceType, type: typeTypeType}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        builtin_nodes.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:       {}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:           {}
+// CHECK:STDOUT:   type_blocks:     {}
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     nodeTypeType:    {kind: CrossReference, arg0: ir0, arg1: nodeTypeType, type: typeTypeType}
+// CHECK:STDOUT:     nodeError:       {kind: CrossReference, arg0: ir0, arg1: nodeError, type: typeError}
+// CHECK:STDOUT:     nodeBoolType:    {kind: CrossReference, arg0: ir0, arg1: nodeBoolType, type: typeTypeType}
+// CHECK:STDOUT:     nodeIntegerType: {kind: CrossReference, arg0: ir0, arg1: nodeIntegerType, type: typeTypeType}
+// CHECK:STDOUT:     nodeFloatingPointType: {kind: CrossReference, arg0: ir0, arg1: nodeFloatingPointType, type: typeTypeType}
+// CHECK:STDOUT:     nodeStringType:  {kind: CrossReference, arg0: ir0, arg1: nodeStringType, type: typeTypeType}
+// CHECK:STDOUT:     nodeFunctionType: {kind: CrossReference, arg0: ir0, arg1: nodeFunctionType, type: typeTypeType}
+// CHECK:STDOUT:     nodeNamespaceType: {kind: CrossReference, arg0: ir0, arg1: nodeNamespaceType, type: typeTypeType}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT: ...
diff --git a/toolchain/check/testdata/basics/multifile_raw_and_textual_ir.carbon b/toolchain/check/testdata/basics/multifile_raw_and_textual_ir.carbon
index 3c706688b4e4..97fb51a9ade2 100644
--- a/toolchain/check/testdata/basics/multifile_raw_and_textual_ir.carbon
+++ b/toolchain/check/testdata/basics/multifile_raw_and_textual_ir.carbon
@@ -14,22 +14,26 @@ fn A() {}
 // --- b.carbon
 fn B() {}
 
-// CHECK:STDOUT: - filename: a.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str0, param_refs: block0, body: [block1]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:     type_blocks: []
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type0}
-// CHECK:STDOUT:       - {kind: Return}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+1
-// CHECK:STDOUT:       - - node+0
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        a.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str0, param_refs: block0, body: [block1]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:   type_blocks:     {}
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: FunctionDeclaration, arg0: function0, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: Return}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+1
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT: ...
 // CHECK:STDOUT:
 // CHECK:STDOUT: file "a.carbon" {
 // CHECK:STDOUT:   %A: <function> = fn_decl @A
@@ -39,22 +43,26 @@ fn B() {}
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
-// CHECK:STDOUT: - filename: b.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str1, param_refs: block0, body: [block1]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:     type_blocks: []
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type0}
-// CHECK:STDOUT:       - {kind: Return}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+1
-// CHECK:STDOUT:       - - node+0
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        b.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str1, param_refs: block0, body: [block1]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:   type_blocks:     {}
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: FunctionDeclaration, arg0: function0, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: Return}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+1
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT: ...
 // CHECK:STDOUT:
 // CHECK:STDOUT: file "b.carbon" {
 // CHECK:STDOUT:   %B: <function> = fn_decl @B
diff --git a/toolchain/check/testdata/basics/multifile_raw_ir.carbon b/toolchain/check/testdata/basics/multifile_raw_ir.carbon
index 19770a279ee7..85683bdda0ae 100644
--- a/toolchain/check/testdata/basics/multifile_raw_ir.carbon
+++ b/toolchain/check/testdata/basics/multifile_raw_ir.carbon
@@ -14,35 +14,43 @@ fn A() {}
 // --- b.carbon
 fn B() {}
 
-// CHECK:STDOUT: - filename: a.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str0, param_refs: block0, body: [block1]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:     type_blocks: []
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type0}
-// CHECK:STDOUT:       - {kind: Return}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+1
-// CHECK:STDOUT:       - - node+0
-// CHECK:STDOUT: - filename: b.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str1, param_refs: block0, body: [block1]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:     type_blocks: []
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type0}
-// CHECK:STDOUT:       - {kind: Return}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+1
-// CHECK:STDOUT:       - - node+0
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        a.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str0, param_refs: block0, body: [block1]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:   type_blocks:     {}
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: FunctionDeclaration, arg0: function0, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: Return}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+1
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT: ...
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        b.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str1, param_refs: block0, body: [block1]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeFunctionType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:   type_blocks:     {}
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: FunctionDeclaration, arg0: function0, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: Return}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+1
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT: ...
diff --git a/toolchain/check/testdata/basics/raw_and_textual_ir.carbon b/toolchain/check/testdata/basics/raw_and_textual_ir.carbon
index d6bfbfdfa667..e24c3068a32f 100644
--- a/toolchain/check/testdata/basics/raw_and_textual_ir.carbon
+++ b/toolchain/check/testdata/basics/raw_and_textual_ir.carbon
@@ -12,70 +12,81 @@ fn Foo(n: i32) -> (i32, f64) {
   return (n + 2, 3.4);
 }
 
-// CHECK:STDOUT: - filename: raw_and_textual_ir.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str0, param_refs: block1, return_type: type3, return_slot: node+4, body: [block4]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeIntegerType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:       - {node: node+1, value_rep: {kind: unknown, type: type<invalid>}}
-// CHECK:STDOUT:       - {node: nodeFloatingPointType, value_rep: {kind: copy, type: type2}}
-// CHECK:STDOUT:       - {node: node+3, value_rep: {kind: pointer, type: type4}}
-// CHECK:STDOUT:       - {node: node+5, value_rep: {kind: copy, type: type4}}
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type5}}
-// CHECK:STDOUT:     type_blocks:
-// CHECK:STDOUT:       - - typeTypeType
-// CHECK:STDOUT:         - typeTypeType
-// CHECK:STDOUT:       - - type0
-// CHECK:STDOUT:         - type2
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: Parameter, arg0: str1, type: type0}
-// CHECK:STDOUT:       - {kind: TupleType, arg0: typeBlock0, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: TupleLiteral, arg0: block2, type: type1}
-// CHECK:STDOUT:       - {kind: TupleType, arg0: typeBlock1, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: VarStorage, arg0: str2, type: type3}
-// CHECK:STDOUT:       - {kind: PointerType, arg0: type3, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type5}
-// CHECK:STDOUT:       - {kind: NameReference, arg0: str1, arg1: node+0, type: type0}
-// CHECK:STDOUT:       - {kind: IntegerLiteral, arg0: int3, type: type0}
-// CHECK:STDOUT:       - {kind: BinaryOperatorAdd, arg0: node+7, arg1: node+8, type: type0}
-// CHECK:STDOUT:       - {kind: RealLiteral, arg0: real0, type: type2}
-// CHECK:STDOUT:       - {kind: TupleLiteral, arg0: block5, type: type3}
-// CHECK:STDOUT:       - {kind: TupleAccess, arg0: node+4, arg1: member0, type: type0}
-// CHECK:STDOUT:       - {kind: InitializeFrom, arg0: node+9, arg1: node+12, type: type0}
-// CHECK:STDOUT:       - {kind: TupleAccess, arg0: node+4, arg1: member1, type: type2}
-// CHECK:STDOUT:       - {kind: InitializeFrom, arg0: node+10, arg1: node+14, type: type2}
-// CHECK:STDOUT:       - {kind: TupleInit, arg0: node+11, arg1: block6, type: type3}
-// CHECK:STDOUT:       - {kind: ReturnExpression, arg0: node+16}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+0
-// CHECK:STDOUT:       - - nodeIntegerType
-// CHECK:STDOUT:         - nodeFloatingPointType
-// CHECK:STDOUT:       - - node+0
-// CHECK:STDOUT:         - node+1
-// CHECK:STDOUT:         - node+2
-// CHECK:STDOUT:         - node+3
-// CHECK:STDOUT:         - node+4
-// CHECK:STDOUT:       - - node+7
-// CHECK:STDOUT:         - node+8
-// CHECK:STDOUT:         - node+9
-// CHECK:STDOUT:         - node+10
-// CHECK:STDOUT:         - node+11
-// CHECK:STDOUT:         - node+12
-// CHECK:STDOUT:         - node+13
-// CHECK:STDOUT:         - node+14
-// CHECK:STDOUT:         - node+15
-// CHECK:STDOUT:         - node+16
-// CHECK:STDOUT:         - node+17
-// CHECK:STDOUT:       - - node+9
-// CHECK:STDOUT:         - node+10
-// CHECK:STDOUT:       - - node+13
-// CHECK:STDOUT:         - node+15
-// CHECK:STDOUT:       - - node+5
-// CHECK:STDOUT:         - node+6
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        raw_and_textual_ir.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str0, param_refs: block1, return_type: type3, return_slot: node+4, body: [block4]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeIntegerType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:     type1:           {node: node+1, value_rep: {kind: unknown, type: type<invalid>}}
+// CHECK:STDOUT:     type2:           {node: nodeFloatingPointType, value_rep: {kind: copy, type: type2}}
+// CHECK:STDOUT:     type3:           {node: node+3, value_rep: {kind: pointer, type: type4}}
+// CHECK:STDOUT:     type4:           {node: node+5, value_rep: {kind: copy, type: type4}}
+// CHECK:STDOUT:     type5:           {node: nodeFunctionType, value_rep: {kind: copy, type: type5}}
+// CHECK:STDOUT:   type_blocks:
+// CHECK:STDOUT:     typeBlock0:
+// CHECK:STDOUT:       0:               typeTypeType
+// CHECK:STDOUT:       1:               typeTypeType
+// CHECK:STDOUT:     typeBlock1:
+// CHECK:STDOUT:       0:               type0
+// CHECK:STDOUT:       1:               type2
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: Parameter, arg0: str1, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: TupleType, arg0: typeBlock0, type: typeTypeType}
+// CHECK:STDOUT:     node+2:          {kind: TupleLiteral, arg0: block2, type: type1}
+// CHECK:STDOUT:     node+3:          {kind: TupleType, arg0: typeBlock1, type: typeTypeType}
+// CHECK:STDOUT:     node+4:          {kind: VarStorage, arg0: str2, type: type3}
+// CHECK:STDOUT:     node+5:          {kind: PointerType, arg0: type3, type: typeTypeType}
+// CHECK:STDOUT:     node+6:          {kind: FunctionDeclaration, arg0: function0, type: type5}
+// CHECK:STDOUT:     node+7:          {kind: NameReference, arg0: str1, arg1: node+0, type: type0}
+// CHECK:STDOUT:     node+8:          {kind: IntegerLiteral, arg0: int3, type: type0}
+// CHECK:STDOUT:     node+9:          {kind: BinaryOperatorAdd, arg0: node+7, arg1: node+8, type: type0}
+// CHECK:STDOUT:     node+10:         {kind: RealLiteral, arg0: real0, type: type2}
+// CHECK:STDOUT:     node+11:         {kind: TupleLiteral, arg0: block5, type: type3}
+// CHECK:STDOUT:     node+12:         {kind: TupleAccess, arg0: node+4, arg1: member0, type: type0}
+// CHECK:STDOUT:     node+13:         {kind: InitializeFrom, arg0: node+9, arg1: node+12, type: type0}
+// CHECK:STDOUT:     node+14:         {kind: TupleAccess, arg0: node+4, arg1: member1, type: type2}
+// CHECK:STDOUT:     node+15:         {kind: InitializeFrom, arg0: node+10, arg1: node+14, type: type2}
+// CHECK:STDOUT:     node+16:         {kind: TupleInit, arg0: node+11, arg1: block6, type: type3}
+// CHECK:STDOUT:     node+17:         {kind: ReturnExpression, arg0: node+16}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               nodeIntegerType
+// CHECK:STDOUT:       1:               nodeFloatingPointType
+// CHECK:STDOUT:     block3:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT:       1:               node+1
+// CHECK:STDOUT:       2:               node+2
+// CHECK:STDOUT:       3:               node+3
+// CHECK:STDOUT:       4:               node+4
+// CHECK:STDOUT:     block4:
+// CHECK:STDOUT:       0:               node+7
+// CHECK:STDOUT:       1:               node+8
+// CHECK:STDOUT:       2:               node+9
+// CHECK:STDOUT:       3:               node+10
+// CHECK:STDOUT:       4:               node+11
+// CHECK:STDOUT:       5:               node+12
+// CHECK:STDOUT:       6:               node+13
+// CHECK:STDOUT:       7:               node+14
+// CHECK:STDOUT:       8:               node+15
+// CHECK:STDOUT:       9:               node+16
+// CHECK:STDOUT:       10:              node+17
+// CHECK:STDOUT:     block5:
+// CHECK:STDOUT:       0:               node+9
+// CHECK:STDOUT:       1:               node+10
+// CHECK:STDOUT:     block6:
+// CHECK:STDOUT:       0:               node+13
+// CHECK:STDOUT:       1:               node+15
+// CHECK:STDOUT:     block7:
+// CHECK:STDOUT:       0:               node+5
+// CHECK:STDOUT:       1:               node+6
+// CHECK:STDOUT: ...
 // CHECK:STDOUT:
 // CHECK:STDOUT: file "raw_and_textual_ir.carbon" {
 // CHECK:STDOUT:   %.loc11: type = ptr_type (i32, f64)
diff --git a/toolchain/check/testdata/basics/raw_ir.carbon b/toolchain/check/testdata/basics/raw_ir.carbon
index 99f50b0c6348..5bb0d0a8fdb6 100644
--- a/toolchain/check/testdata/basics/raw_ir.carbon
+++ b/toolchain/check/testdata/basics/raw_ir.carbon
@@ -12,67 +12,78 @@ fn Foo(n: i32) -> (i32, f64) {
   return (n + 2, 3.4);
 }
 
-// CHECK:STDOUT: - filename: raw_ir.carbon
-// CHECK:STDOUT:   sem_ir:
-// CHECK:STDOUT:   - cross_reference_irs_size: 1
-// CHECK:STDOUT:     functions:
-// CHECK:STDOUT:       - {name: str0, param_refs: block1, return_type: type3, return_slot: node+4, body: [block4]}
-// CHECK:STDOUT:     classes: []
-// CHECK:STDOUT:     types:
-// CHECK:STDOUT:       - {node: nodeIntegerType, value_rep: {kind: copy, type: type0}}
-// CHECK:STDOUT:       - {node: node+1, value_rep: {kind: unknown, type: type<invalid>}}
-// CHECK:STDOUT:       - {node: nodeFloatingPointType, value_rep: {kind: copy, type: type2}}
-// CHECK:STDOUT:       - {node: node+3, value_rep: {kind: pointer, type: type4}}
-// CHECK:STDOUT:       - {node: node+5, value_rep: {kind: copy, type: type4}}
-// CHECK:STDOUT:       - {node: nodeFunctionType, value_rep: {kind: copy, type: type5}}
-// CHECK:STDOUT:     type_blocks:
-// CHECK:STDOUT:       - - typeTypeType
-// CHECK:STDOUT:         - typeTypeType
-// CHECK:STDOUT:       - - type0
-// CHECK:STDOUT:         - type2
-// CHECK:STDOUT:     nodes:
-// CHECK:STDOUT:       - {kind: Parameter, arg0: str1, type: type0}
-// CHECK:STDOUT:       - {kind: TupleType, arg0: typeBlock0, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: TupleLiteral, arg0: block2, type: type1}
-// CHECK:STDOUT:       - {kind: TupleType, arg0: typeBlock1, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: VarStorage, arg0: str2, type: type3}
-// CHECK:STDOUT:       - {kind: PointerType, arg0: type3, type: typeTypeType}
-// CHECK:STDOUT:       - {kind: FunctionDeclaration, arg0: function0, type: type5}
-// CHECK:STDOUT:       - {kind: NameReference, arg0: str1, arg1: node+0, type: type0}
-// CHECK:STDOUT:       - {kind: IntegerLiteral, arg0: int3, type: type0}
-// CHECK:STDOUT:       - {kind: BinaryOperatorAdd, arg0: node+7, arg1: node+8, type: type0}
-// CHECK:STDOUT:       - {kind: RealLiteral, arg0: real0, type: type2}
-// CHECK:STDOUT:       - {kind: TupleLiteral, arg0: block5, type: type3}
-// CHECK:STDOUT:       - {kind: TupleAccess, arg0: node+4, arg1: member0, type: type0}
-// CHECK:STDOUT:       - {kind: InitializeFrom, arg0: node+9, arg1: node+12, type: type0}
-// CHECK:STDOUT:       - {kind: TupleAccess, arg0: node+4, arg1: member1, type: type2}
-// CHECK:STDOUT:       - {kind: InitializeFrom, arg0: node+10, arg1: node+14, type: type2}
-// CHECK:STDOUT:       - {kind: TupleInit, arg0: node+11, arg1: block6, type: type3}
-// CHECK:STDOUT:       - {kind: ReturnExpression, arg0: node+16}
-// CHECK:STDOUT:     node_blocks:
-// CHECK:STDOUT:       - []
-// CHECK:STDOUT:       - - node+0
-// CHECK:STDOUT:       - - nodeIntegerType
-// CHECK:STDOUT:         - nodeFloatingPointType
-// CHECK:STDOUT:       - - node+0
-// CHECK:STDOUT:         - node+1
-// CHECK:STDOUT:         - node+2
-// CHECK:STDOUT:         - node+3
-// CHECK:STDOUT:         - node+4
-// CHECK:STDOUT:       - - node+7
-// CHECK:STDOUT:         - node+8
-// CHECK:STDOUT:         - node+9
-// CHECK:STDOUT:         - node+10
-// CHECK:STDOUT:         - node+11
-// CHECK:STDOUT:         - node+12
-// CHECK:STDOUT:         - node+13
-// CHECK:STDOUT:         - node+14
-// CHECK:STDOUT:         - node+15
-// CHECK:STDOUT:         - node+16
-// CHECK:STDOUT:         - node+17
-// CHECK:STDOUT:       - - node+9
-// CHECK:STDOUT:         - node+10
-// CHECK:STDOUT:       - - node+13
-// CHECK:STDOUT:         - node+15
-// CHECK:STDOUT:       - - node+5
-// CHECK:STDOUT:         - node+6
+// CHECK:STDOUT: ---
+// CHECK:STDOUT: filename:        raw_ir.carbon
+// CHECK:STDOUT: sem_ir:
+// CHECK:STDOUT:   cross_reference_irs_size: 1
+// CHECK:STDOUT:   functions:
+// CHECK:STDOUT:     function0:       {name: str0, param_refs: block1, return_type: type3, return_slot: node+4, body: [block4]}
+// CHECK:STDOUT:   classes:         {}
+// CHECK:STDOUT:   types:
+// CHECK:STDOUT:     type0:           {node: nodeIntegerType, value_rep: {kind: copy, type: type0}}
+// CHECK:STDOUT:     type1:           {node: node+1, value_rep: {kind: unknown, type: type<invalid>}}
+// CHECK:STDOUT:     type2:           {node: nodeFloatingPointType, value_rep: {kind: copy, type: type2}}
+// CHECK:STDOUT:     type3:           {node: node+3, value_rep: {kind: pointer, type: type4}}
+// CHECK:STDOUT:     type4:           {node: node+5, value_rep: {kind: copy, type: type4}}
+// CHECK:STDOUT:     type5:           {node: nodeFunctionType, value_rep: {kind: copy, type: type5}}
+// CHECK:STDOUT:   type_blocks:
+// CHECK:STDOUT:     typeBlock0:
+// CHECK:STDOUT:       0:               typeTypeType
+// CHECK:STDOUT:       1:               typeTypeType
+// CHECK:STDOUT:     typeBlock1:
+// CHECK:STDOUT:       0:               type0
+// CHECK:STDOUT:       1:               type2
+// CHECK:STDOUT:   nodes:
+// CHECK:STDOUT:     node+0:          {kind: Parameter, arg0: str1, type: type0}
+// CHECK:STDOUT:     node+1:          {kind: TupleType, arg0: typeBlock0, type: typeTypeType}
+// CHECK:STDOUT:     node+2:          {kind: TupleLiteral, arg0: block2, type: type1}
+// CHECK:STDOUT:     node+3:          {kind: TupleType, arg0: typeBlock1, type: typeTypeType}
+// CHECK:STDOUT:     node+4:          {kind: VarStorage, arg0: str2, type: type3}
+// CHECK:STDOUT:     node+5:          {kind: PointerType, arg0: type3, type: typeTypeType}
+// CHECK:STDOUT:     node+6:          {kind: FunctionDeclaration, arg0: function0, type: type5}
+// CHECK:STDOUT:     node+7:          {kind: NameReference, arg0: str1, arg1: node+0, type: type0}
+// CHECK:STDOUT:     node+8:          {kind: IntegerLiteral, arg0: int3, type: type0}
+// CHECK:STDOUT:     node+9:          {kind: BinaryOperatorAdd, arg0: node+7, arg1: node+8, type: type0}
+// CHECK:STDOUT:     node+10:         {kind: RealLiteral, arg0: real0, type: type2}
+// CHECK:STDOUT:     node+11:         {kind: TupleLiteral, arg0: block5, type: type3}
+// CHECK:STDOUT:     node+12:         {kind: TupleAccess, arg0: node+4, arg1: member0, type: type0}
+// CHECK:STDOUT:     node+13:         {kind: InitializeFrom, arg0: node+9, arg1: node+12, type: type0}
+// CHECK:STDOUT:     node+14:         {kind: TupleAccess, arg0: node+4, arg1: member1, type: type2}
+// CHECK:STDOUT:     node+15:         {kind: InitializeFrom, arg0: node+10, arg1: node+14, type: type2}
+// CHECK:STDOUT:     node+16:         {kind: TupleInit, arg0: node+11, arg1: block6, type: type3}
+// CHECK:STDOUT:     node+17:         {kind: ReturnExpression, arg0: node+16}
+// CHECK:STDOUT:   node_blocks:
+// CHECK:STDOUT:     block0:          {}
+// CHECK:STDOUT:     block1:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT:     block2:
+// CHECK:STDOUT:       0:               nodeIntegerType
+// CHECK:STDOUT:       1:               nodeFloatingPointType
+// CHECK:STDOUT:     block3:
+// CHECK:STDOUT:       0:               node+0
+// CHECK:STDOUT:       1:               node+1
+// CHECK:STDOUT:       2:               node+2
+// CHECK:STDOUT:       3:               node+3
+// CHECK:STDOUT:       4:               node+4
+// CHECK:STDOUT:     block4:
+// CHECK:STDOUT:       0:               node+7
+// CHECK:STDOUT:       1:               node+8
+// CHECK:STDOUT:       2:               node+9
+// CHECK:STDOUT:       3:               node+10
+// CHECK:STDOUT:       4:               node+11
+// CHECK:STDOUT:       5:               node+12
+// CHECK:STDOUT:       6:               node+13
+// CHECK:STDOUT:       7:               node+14
+// CHECK:STDOUT:       8:               node+15
+// CHECK:STDOUT:       9:               node+16
+// CHECK:STDOUT:       10:              node+17
+// CHECK:STDOUT:     block5:
+// CHECK:STDOUT:       0:               node+9
+// CHECK:STDOUT:       1:               node+10
+// CHECK:STDOUT:     block6:
+// CHECK:STDOUT:       0:               node+13
+// CHECK:STDOUT:       1:               node+15
+// CHECK:STDOUT:     block7:
+// CHECK:STDOUT:       0:               node+5
+// CHECK:STDOUT:       1:               node+6
+// CHECK:STDOUT: ...
diff --git a/toolchain/driver/testdata/dump_shared_values.carbon b/toolchain/driver/testdata/dump_shared_values.carbon
index 03c5d6b3eef9..cfe5382c96e9 100644
--- a/toolchain/driver/testdata/dump_shared_values.carbon
+++ b/toolchain/driver/testdata/dump_shared_values.carbon
@@ -15,26 +15,28 @@ var real3: f64 = 0.8e9;
 var str1: String = "abc";
 var str2: String = "ab'\"c";
 
+// CHECK:STDOUT: ---
 // CHECK:STDOUT: shared_values:
-// CHECK:STDOUT:   - integers:
-// CHECK:STDOUT:       - 32
-// CHECK:STDOUT:       - 1
-// CHECK:STDOUT:       - 32
-// CHECK:STDOUT:       - 8
-// CHECK:STDOUT:       - 64
-// CHECK:STDOUT:       - 64
-// CHECK:STDOUT:       - 64
-// CHECK:STDOUT:     reals:
-// CHECK:STDOUT:       - 10*10^-1
-// CHECK:STDOUT:       - 8*10^7
-// CHECK:STDOUT:       - 8*10^8
-// CHECK:STDOUT:     strings:
-// CHECK:STDOUT:       - "int1"
-// CHECK:STDOUT:       - "int2"
-// CHECK:STDOUT:       - "real1"
-// CHECK:STDOUT:       - "real2"
-// CHECK:STDOUT:       - "real3"
-// CHECK:STDOUT:       - "str1"
-// CHECK:STDOUT:       - "abc"
-// CHECK:STDOUT:       - "str2"
-// CHECK:STDOUT:       - "ab'\"c"
+// CHECK:STDOUT:   integers:
+// CHECK:STDOUT:     int0:            32
+// CHECK:STDOUT:     int1:            1
+// CHECK:STDOUT:     int2:            32
+// CHECK:STDOUT:     int3:            8
+// CHECK:STDOUT:     int4:            64
+// CHECK:STDOUT:     int5:            64
+// CHECK:STDOUT:     int6:            64
+// CHECK:STDOUT:   reals:
+// CHECK:STDOUT:     real0:           10*10^-1
+// CHECK:STDOUT:     real1:           8*10^7
+// CHECK:STDOUT:     real2:           8*10^8
+// CHECK:STDOUT:   strings:
+// CHECK:STDOUT:     str0:            int1
+// CHECK:STDOUT:     str1:            int2
+// CHECK:STDOUT:     str2:            real1
+// CHECK:STDOUT:     str3:            real2
+// CHECK:STDOUT:     str4:            real3
+// CHECK:STDOUT:     str5:            str1
+// CHECK:STDOUT:     str6:            abc
+// CHECK:STDOUT:     str7:            str2
+// CHECK:STDOUT:     str8:            'ab''"c'
+// CHECK:STDOUT: ...
diff --git a/toolchain/lex/tokenized_buffer_test.cpp b/toolchain/lex/tokenized_buffer_test.cpp
index cbec6c8c7290..3e2ce3da5945 100644
--- a/toolchain/lex/tokenized_buffer_test.cpp
+++ b/toolchain/lex/tokenized_buffer_test.cpp
@@ -1057,7 +1057,7 @@ TEST_F(LexerTest, DiagnosticUnrecognizedChar) {
   Lex("\b", consumer);
 }
 
-TEST_F(LexerTest, PrintingAsYaml) {
+TEST_F(LexerTest, PrintingOutputYaml) {
   // Test that we can parse this into YAML and verify line and indent data.
   auto buffer = Lex("\n ;\n\n\n; ;\n\n\n\n\n\n\n\n\n\n\n");
   ASSERT_FALSE(buffer.has_errors());
diff --git a/toolchain/sem_ir/BUILD b/toolchain/sem_ir/BUILD
index 074bce5e8d36..14512668f0dc 100644
--- a/toolchain/sem_ir/BUILD
+++ b/toolchain/sem_ir/BUILD
@@ -69,6 +69,7 @@ cc_library(
         ":value_stores",
         "//common:check",
         "//toolchain/base:value_store",
+        "//toolchain/base:yaml",
         "@llvm-project//llvm:Support",
     ],
 )
@@ -102,6 +103,7 @@ cc_library(
     deps = [
         ":node",
         "//toolchain/base:value_store",
+        "//toolchain/base:yaml",
         "@llvm-project//llvm:Support",
     ],
 )
diff --git a/toolchain/sem_ir/file.cpp b/toolchain/sem_ir/file.cpp
index 594bde0d4ce4..5e22e067bccd 100644
--- a/toolchain/sem_ir/file.cpp
+++ b/toolchain/sem_ir/file.cpp
@@ -8,6 +8,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "toolchain/base/value_store.h"
+#include "toolchain/base/yaml.h"
 #include "toolchain/sem_ir/builtin_kind.h"
 #include "toolchain/sem_ir/node.h"
 #include "toolchain/sem_ir/node_kind.h"
@@ -129,27 +130,30 @@ auto File::Verify() const -> ErrorOr<Success> {
   return Success();
 }
 
-auto File::Print(llvm::raw_ostream& out, bool include_builtins) const -> void {
-  out << "- filename: " << filename_ << "\n"
-      << "  sem_ir:\n"
-      << "  - cross_reference_irs_size: " << cross_reference_irs_.size()
-      << "\n";
-
-  static constexpr int FirstLineIndent = 4;
-  static constexpr int LaterIndent = 6;
-  functions_.Print(out, "functions", FirstLineIndent, LaterIndent);
-  classes_.Print(out, "classes", FirstLineIndent, LaterIndent);
-  types_.Print(out, "types", FirstLineIndent, LaterIndent);
-  type_blocks_.Print(out, "type_blocks", FirstLineIndent, LaterIndent);
-
-  auto nodes = nodes_.array_ref();
-  if (!include_builtins) {
-    nodes = nodes.drop_front(BuiltinKind::ValidCount);
-  }
-  PrintValueRange(out, llvm::iterator_range(nodes), "nodes", FirstLineIndent,
-                  LaterIndent, /*trailing_newline=*/true);
-
-  node_blocks_.Print(out, "node_blocks", FirstLineIndent, LaterIndent);
+auto File::OutputYaml(bool include_builtins) const -> Yaml::OutputMapping {
+  return Yaml::OutputMapping([this,
+                              include_builtins](Yaml::OutputMapping::Map map) {
+    map.Add("filename", filename_);
+    map.Add("sem_ir", Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+              map.Add("cross_reference_irs_size",
+                      Yaml::OutputScalar(cross_reference_irs_.size()));
+              map.Add("functions", functions_.OutputYaml());
+              map.Add("classes", classes_.OutputYaml());
+              map.Add("types", types_.OutputYaml());
+              map.Add("type_blocks", type_blocks_.OutputYaml());
+              map.Add("nodes",
+                      Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+                        int start =
+                            include_builtins ? 0 : BuiltinKind::ValidCount;
+                        for (int i : llvm::seq(start, nodes_.size())) {
+                          auto id = NodeId(i);
+                          map.Add(PrintToString(id),
+                                  Yaml::OutputScalar(nodes_.Get(id)));
+                        }
+                      }));
+              map.Add("node_blocks", node_blocks_.OutputYaml());
+            }));
+  });
 }
 
 // Map a node kind representing a type into an integer describing the
diff --git a/toolchain/sem_ir/file.h b/toolchain/sem_ir/file.h
index e7c1f017a382..79553fefc6a2 100644
--- a/toolchain/sem_ir/file.h
+++ b/toolchain/sem_ir/file.h
@@ -10,6 +10,7 @@
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "toolchain/base/value_store.h"
+#include "toolchain/base/yaml.h"
 #include "toolchain/sem_ir/node.h"
 #include "toolchain/sem_ir/value_stores.h"
 
@@ -174,11 +175,11 @@ class File : public Printable<File> {
   // TODO: In the future, the things to print may change, for example by adding
   // preludes. We may then want the ability to omit other things similar to
   // builtins.
-  auto Print(llvm::raw_ostream& out, bool include_builtins) const -> void;
-
-  auto Print(llvm::raw_ostream& out) const -> void {
-    Print(out, /*include_builtins=*/false);
+  auto Print(llvm::raw_ostream& out, bool include_builtins = false) const
+      -> void {
+    Yaml::Print(out, OutputYaml(include_builtins));
   }
+  auto OutputYaml(bool include_builtins) const -> Yaml::OutputMapping;
 
   // Returns array bound value from the bound node.
   auto GetArrayBoundValue(NodeId bound_id) const -> uint64_t {
diff --git a/toolchain/sem_ir/value_stores.h b/toolchain/sem_ir/value_stores.h
index e1c8431253e7..d91d277ea884 100644
--- a/toolchain/sem_ir/value_stores.h
+++ b/toolchain/sem_ir/value_stores.h
@@ -7,6 +7,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "toolchain/base/value_store.h"
+#include "toolchain/base/yaml.h"
 #include "toolchain/sem_ir/node.h"
 
 namespace Carbon::SemIR {
@@ -72,7 +73,7 @@ class NameScopeStore {
 // BlockValueStore is used as-is, but there are also children that expose the
 // protected members for type-specific functionality.
 template <typename IdT, typename ValueT>
-class BlockValueStore {
+class BlockValueStore : public Yaml::Printable<BlockValueStore<IdT, ValueT>> {
  public:
   explicit BlockValueStore(llvm::BumpPtrAllocator& allocator)
       : allocator_(&allocator) {}
@@ -88,18 +89,19 @@ class BlockValueStore {
   // Returns the requested block.
   auto Get(IdT id) -> llvm::MutableArrayRef<ValueT> { return values_.Get(id); }
 
-  auto Print(llvm::raw_ostream& out) const -> void {
-    Print(out, std::nullopt, 0, 0);
-  }
-  auto Print(llvm::raw_ostream& out, std::optional<llvm::StringRef> label,
-             int first_line_indent, int later_indent) const -> void {
-    values_.Print(out, label, first_line_indent, later_indent,
-                  [&](llvm::raw_ostream& out,
-                      const llvm::MutableArrayRef<ValueT>& value) {
-                    PrintValueRange<ValueT>(out, llvm::iterator_range(value),
-                                            std::nullopt, 0, later_indent + 2,
-                                            /*trailing_newline=*/false);
-                  });
+  auto OutputYaml() const -> Yaml::OutputMapping {
+    return Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+      for (auto block_index : llvm::seq(values_.size())) {
+        auto block_id = IdT(block_index);
+        map.Add(PrintToString(block_id),
+                Yaml::OutputMapping([&](Yaml::OutputMapping::Map map) {
+                  auto block = Get(block_id);
+                  for (auto i : llvm::seq(block.size())) {
+                    map.Add(llvm::itostr(i), Yaml::OutputScalar(block[i]));
+                  }
+                }));
+      }
+    });
   }
 
   auto size() const -> int { return values_.size(); }
diff --git a/toolchain/sem_ir/yaml_test.cpp b/toolchain/sem_ir/yaml_test.cpp
index 0f0e58224673..d225ac282882 100644
--- a/toolchain/sem_ir/yaml_test.cpp
+++ b/toolchain/sem_ir/yaml_test.cpp
@@ -44,40 +44,45 @@ TEST(SemIRTest, YAML) {
   auto node_id = Yaml::Scalar(MatchesRegex(R"(node\+\d+)"));
   auto node_builtin = Yaml::Scalar(MatchesRegex(R"(node\w+)"));
   auto type_id = Yaml::Scalar(MatchesRegex(R"(type\d+)"));
-  auto type_builtin = Yaml::Mapping(ElementsAre(
-      Pair("node", node_builtin), Pair("value_rep", Yaml::Mapping(_))));
+  auto type_builtin = Pair(
+      type_id, Yaml::Mapping(ElementsAre(Pair("node", node_builtin),
+                                         Pair("value_rep", Yaml::Mapping(_)))));
 
-  auto file = Yaml::Sequence(ElementsAre(Yaml::Mapping(ElementsAre(
+  auto file = Yaml::Mapping(ElementsAre(
       Pair("cross_reference_irs_size", "1"),
-      Pair("functions", Yaml::Sequence(SizeIs(1))),
-      Pair("classes", Yaml::Sequence(SizeIs(0))),
-      Pair("types", Yaml::Sequence(Each(type_builtin))),
-      Pair("type_blocks", Yaml::Sequence(IsEmpty())),
+      Pair("functions", Yaml::Mapping(SizeIs(1))),
+      Pair("classes", Yaml::Mapping(SizeIs(0))),
+      Pair("types", Yaml::Mapping(Each(type_builtin))),
+      Pair("type_blocks", Yaml::Mapping(IsEmpty())),
       Pair("nodes",
-           Yaml::Sequence(AllOf(
+           Yaml::Mapping(AllOf(
+               Each(Key(node_id)),
                // kind is required, other parts are optional.
-               Each(Yaml::Mapping(Contains(Pair("kind", _)))),
+               Each(Pair(_, Yaml::Mapping(Contains(Pair("kind", _))))),
                // A 0-arg node.
-               Contains(Yaml::Mapping(ElementsAre(Pair("kind", "Return")))),
+               Contains(
+                   Pair(_, Yaml::Mapping(ElementsAre(Pair("kind", "Return"))))),
                // A 1-arg node.
-               Contains(Yaml::Mapping(ElementsAre(
-                   Pair("kind", "IntegerLiteral"), Pair("arg0", integer_id),
-                   Pair("type", type_id)))),
+               Contains(Pair(
+                   _, Yaml::Mapping(ElementsAre(Pair("kind", "IntegerLiteral"),
+                                                Pair("arg0", integer_id),
+                                                Pair("type", type_id))))),
                // A 2-arg node.
-               Contains(Yaml::Mapping(ElementsAre(Pair("kind", "Assign"),
-                                                  Pair("arg0", node_id),
-                                                  Pair("arg1", node_id))))))),
+               Contains(Pair(
+                   _, Yaml::Mapping(ElementsAre(Pair("kind", "Assign"),
+                                                Pair("arg0", node_id),
+                                                Pair("arg1", node_id)))))))),
       // This production has only two node blocks.
       Pair("node_blocks",
-           Yaml::Sequence(ElementsAre(Yaml::Sequence(IsEmpty()),
-                                      Yaml::Sequence(Each(node_id)),
-                                      Yaml::Sequence(Each(node_id)))))))));
+           Yaml::Mapping(ElementsAre(
+               Pair("block0", Yaml::Mapping(IsEmpty())),
+               Pair("block1", Yaml::Mapping(Each(Pair(_, node_id)))),
+               Pair("block2", Yaml::Mapping(Each(Pair(_, node_id)))))))));
 
   auto root = Yaml::Sequence(ElementsAre(Yaml::Mapping(
       ElementsAre(Pair("filename", "test.carbon"), Pair("sem_ir", file)))));
 
-  EXPECT_THAT(Yaml::Value::FromText(print_stream.TakeStr()),
-              IsYaml(ElementsAre(root)));
+  EXPECT_THAT(Yaml::Value::FromText(print_stream.TakeStr()), IsYaml(root));
 }
 
 }  // namespace