diff --git a/llvm/include/llvm/ProfileData/MemProf.h b/llvm/include/llvm/ProfileData/MemProf.h
index fe017913f6de2..5af460efb6ddf 100644
--- a/llvm/include/llvm/ProfileData/MemProf.h
+++ b/llvm/include/llvm/ProfileData/MemProf.h
@@ -1177,6 +1177,10 @@ template <> struct MappingTraits<memprof::Frame> {
     (void)Column;
     (void)IsInlineFrame;
   }
+
+  // Request the inline notation for brevity:
+  //   { Function: 123, LineOffset: 11, Column: 10; IsInlineFrame: true }
+  static const bool flow = true;
 };
 
 template <> struct CustomMappingTraits<memprof::PortableMemInfoBlock> {
@@ -1201,8 +1205,13 @@ template <> struct CustomMappingTraits<memprof::PortableMemInfoBlock> {
     Io.setError("Key is not a valid validation event");
   }
 
-  static void output(IO &Io, memprof::PortableMemInfoBlock &VI) {
-    llvm_unreachable("To be implemented");
+  static void output(IO &Io, memprof::PortableMemInfoBlock &MIB) {
+    auto Schema = MIB.getSchema();
+#define MIBEntryDef(NameTag, Name, Type)                                       \
+  if (Schema.test(llvm::to_underlying(memprof::Meta::Name)))                   \
+    Io.mapRequired(#Name, MIB.Name);
+#include "llvm/ProfileData/MIBEntryDef.inc"
+#undef MIBEntryDef
   }
 };
 
diff --git a/llvm/unittests/ProfileData/MemProfTest.cpp b/llvm/unittests/ProfileData/MemProfTest.cpp
index 2f8589bbfbb96..83383eeaa3fe6 100644
--- a/llvm/unittests/ProfileData/MemProfTest.cpp
+++ b/llvm/unittests/ProfileData/MemProfTest.cpp
@@ -807,4 +807,40 @@ TEST(MemProf, YAMLParser) {
   EXPECT_THAT(Record.CallSiteIds,
               ElementsAre(hashCallStack(CS3), hashCallStack(CS4)));
 }
+
+template <typename T> std::string serializeInYAML(T &Val) {
+  std::string Out;
+  llvm::raw_string_ostream OS(Out);
+  llvm::yaml::Output Yout(OS);
+  Yout << Val;
+  return Out;
+}
+
+TEST(MemProf, YAMLWriterFrame) {
+  Frame F(11, 22, 33, true);
+
+  std::string Out = serializeInYAML(F);
+  EXPECT_EQ(Out, R"YAML(---
+{ Function: 11, LineOffset: 22, Column: 33, Inline: true }
+...
+)YAML");
+}
+
+TEST(MemProf, YAMLWriterMIB) {
+  MemInfoBlock MIB;
+  MIB.AllocCount = 111;
+  MIB.TotalSize = 222;
+  MIB.TotalLifetime = 333;
+  MIB.TotalLifetimeAccessDensity = 444;
+  PortableMemInfoBlock PMIB(MIB, llvm::memprof::getHotColdSchema());
+
+  std::string Out = serializeInYAML(PMIB);
+  EXPECT_EQ(Out, R"YAML(---
+AllocCount:      111
+TotalSize:       222
+TotalLifetime:   333
+TotalLifetimeAccessDensity: 444
+...
+)YAML");
+}
 } // namespace