diff --git a/libc/benchmarks/MemorySizeDistributions.cpp b/libc/benchmarks/MemorySizeDistributions.cpp
diff --git a/libc/benchmarks/MemorySizeDistributions.h b/libc/benchmarks/MemorySizeDistributions.h
@@ -0,0 +1,44 @@
+//===-- MemorySizeDistributions ---------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Memory functions operate on buffers of certain sizes. This file provides
+// probability distributions observed at runtime for a set of applications.
+// These distributions are used to benchmark and compare memory functions
+// implementations.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_BENCHMARKS_MEMORYSIZEDISTRIBUTIONS_H
+#define LLVM_LIBC_BENCHMARKS_MEMORYSIZEDISTRIBUTIONS_H
+
+#include <llvm/ADT/ArrayRef.h>
+#include <llvm/ADT/StringRef.h>
+
+namespace llvm {
+namespace libc_benchmarks {
+
+/// A simple POD exposing caracteristics of a memory function size
+/// distributions. The underlying data is immutable.
+struct MemorySizeDistribution {
+  StringRef Name;                 // The name of the distribution.
+  ArrayRef<double> Probabilities; // Size indexed array of probabilities.
+};
+
+/// Returns a list of memcpy size distributions.
+ArrayRef<MemorySizeDistribution> getMemcpySizeDistributions();
+
+/// Returns a list of memset size distributions.
+ArrayRef<MemorySizeDistribution> getMemsetSizeDistributions();
+
+/// Returns a list of memcmp size distributions.
+ArrayRef<MemorySizeDistribution> getMemcmpSizeDistributions();
+
+} // namespace libc_benchmarks
+} // namespace llvm
+
+#endif // LLVM_LIBC_BENCHMARKS_MEMORYSIZEDISTRIBUTIONS_H