Index: include/llvm/Support/Format.h
===================================================================
--- include/llvm/Support/Format.h
+++ include/llvm/Support/Format.h
@@ -252,6 +252,27 @@
                         ByteGroupSize, Upper, true);
 }
 
+/// This is a helper class used for format_memory.
+class FormattedMemory {
+  friend class raw_ostream;
+  const double NumBytes;
+  const unsigned Width;
+public:
+  FormattedMemory(double NB, unsigned W = 2) : NumBytes(NB), Width(W) {}
+};
+
+/// format_memory - Output \p NB as human readable amount of memory. When the
+/// amount is greater than half the amount for the next suffix the next suffix
+/// is used.  If no suffix exists for the amount of bytes, then the number is
+/// printed as is.
+///   OS << format_decimal(1024, 2)          => "1.00 kB"
+///   OS << format_decimal(524288, 2)        => "0.50 MB"
+///   OS << format_decimal(1048576, 4)       => "1.0000 MB"
+///   OS << format_decimal(pow(1024, 5), 3)  => "1.000 PB"
+inline FormattedMemory format_memory(double NB, unsigned W = 2) {
+  return FormattedMemory(NB, W);
+}
+
 } // end namespace llvm
 
 #endif
Index: include/llvm/Support/raw_ostream.h
===================================================================
--- include/llvm/Support/raw_ostream.h
+++ include/llvm/Support/raw_ostream.h
@@ -30,6 +30,7 @@
 class FormattedString;
 class FormattedNumber;
 class FormattedBytes;
+class FormattedMemory;
 
 namespace sys {
 namespace fs {
@@ -235,6 +236,9 @@
   // Formatted output, see the format_bytes() function in Support/Format.h.
   raw_ostream &operator<<(const FormattedBytes &);
 
+  // Formatted output, see the format_memory() function in Support/Format.h.
+  raw_ostream &operator<<(const FormattedMemory &);
+
   /// indent - Insert 'NumSpaces' spaces.
   raw_ostream &indent(unsigned NumSpaces);
 
Index: lib/Support/raw_ostream.cpp
===================================================================
--- lib/Support/raw_ostream.cpp
+++ lib/Support/raw_ostream.cpp
@@ -448,6 +448,37 @@
   return *this;
 }
 
+raw_ostream &raw_ostream::operator<<(const FormattedMemory &FM) {
+  constexpr size_t NumSuffixes = 8;
+  struct ByteTable {
+    ByteTable() {
+      for (size_t I = 0; I <= NumSuffixes; ++I)
+        Table[I] = std::pow(1024, I + 1);
+    }
+    double operator[](int I) const { return Table[I]; }
+    double Table[NumSuffixes + 1];
+  };
+
+  if (FM.NumBytes >= 1024) {
+    static const ByteTable BT;
+    static const char Suffix[NumSuffixes][3] = {"kB", "MB", "GB", "TB",
+                                                "PB", "EB", "ZB", "YB"};
+    for (size_t I = 1; I <= NumSuffixes; ++I) {
+      if (FM.NumBytes < BT[I] * 0.5) {
+        this->operator<<(
+            llvm::format("%.*f ", FM.Width, FM.NumBytes / BT[I - 1]));
+        this->operator<<(Suffix[I - 1]);
+        return *this;
+      }
+    }
+  this->operator<<("?? ");
+  this->operator<<(FM.NumBytes);
+  this->operator<<(" ??");
+  }
+  this->operator<<(llvm::format("%.0f B", FM.NumBytes));
+  return *this;
+}
+
 /// indent - Insert 'NumSpaces' spaces.
 raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
   static const char Spaces[] = "                                "
Index: unittests/Support/raw_ostream_test.cpp
===================================================================
--- unittests/Support/raw_ostream_test.cpp
+++ unittests/Support/raw_ostream_test.cpp
@@ -13,6 +13,8 @@
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 
+#include <cmath>
+
 using namespace llvm;
 
 namespace {
@@ -158,6 +160,28 @@
   EXPECT_EQ("none",    printToString(center_justify("none", 1), 1));
 }
 
+TEST(raw_ostreamTest, FormatMemory) {
+  EXPECT_EQ("1.00 kB", printToString(llvm::format_memory(1024)));
+  EXPECT_EQ("1.00 MB", printToString(llvm::format_memory(std::pow(1024, 2))));
+  EXPECT_EQ("1.00 GB", printToString(llvm::format_memory(std::pow(1024, 3))));
+  EXPECT_EQ("1.00 TB", printToString(llvm::format_memory(std::pow(1024, 4))));
+  EXPECT_EQ("1.00 PB", printToString(llvm::format_memory(std::pow(1024, 5))));
+  EXPECT_EQ("1.00 EB", printToString(llvm::format_memory(std::pow(1024, 6))));
+  EXPECT_EQ("1.00 ZB", printToString(llvm::format_memory(std::pow(1024, 7))));
+  EXPECT_EQ("1.00 YB", printToString(llvm::format_memory(std::pow(1024, 8))));
+
+  EXPECT_EQ("256.00 kB", printToString(llvm::format_memory(262144)));
+  EXPECT_EQ("0.50 MB", printToString(llvm::format_memory(262144*2)));
+
+  EXPECT_EQ("0.50 PB",
+            printToString(llvm::format_memory(std::pow(1024, 5) * 0.5)));
+  EXPECT_EQ("409.60 TB",
+            printToString(llvm::format_memory(std::pow(1024, 5) * 0.4)));
+
+  EXPECT_EQ("0.5010 TB", printToString(llvm::format_memory(
+                             std::pow(1024, 3) + std::pow(1024, 4) * 0.5, 4)));
+}
+
 TEST(raw_ostreamTest, FormatHex) {  
   EXPECT_EQ("0x1234",     printToString(format_hex(0x1234, 6), 6));
   EXPECT_EQ("0x001234",   printToString(format_hex(0x1234, 8), 8));