diff --git a/llvm/include/llvm/BinaryFormat/COFF.h b/llvm/include/llvm/BinaryFormat/COFF.h
--- a/llvm/include/llvm/BinaryFormat/COFF.h
+++ b/llvm/include/llvm/BinaryFormat/COFF.h
@@ -731,6 +731,10 @@
   return SectionNumber <= 0;
 }
 
+/// Encode section name based on string table offset.
+/// The size of Out must be at least COFF::NameSize.
+bool encodeSectionName(char *Out, uint64_t Offset);
+
 } // End namespace COFF.
 } // End namespace llvm.
 
diff --git a/llvm/lib/BinaryFormat/CMakeLists.txt b/llvm/lib/BinaryFormat/CMakeLists.txt
--- a/llvm/lib/BinaryFormat/CMakeLists.txt
+++ b/llvm/lib/BinaryFormat/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_llvm_component_library(LLVMBinaryFormat
   AMDGPUMetadataVerifier.cpp
+  COFF.cpp
   Dwarf.cpp
   ELF.cpp
   MachO.cpp
diff --git a/llvm/lib/BinaryFormat/COFF.cpp b/llvm/lib/BinaryFormat/COFF.cpp
new file mode 100644
--- /dev/null
+++ b/llvm/lib/BinaryFormat/COFF.cpp
@@ -0,0 +1,57 @@
+//===- llvm/BinaryFormat/COFF.cpp - The COFF format -----------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/BinaryFormat/COFF.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Twine.h"
+
+// Maximum offsets for different string table entry encodings.
+enum : unsigned { Max7DecimalOffset = 9999999U };
+enum : uint64_t { MaxBase64Offset = 0xFFFFFFFFFULL }; // 64^6, including 0
+
+// Encode a string table entry offset in base 64, padded to 6 chars, and
+// prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
+// Buffer must be at least 8 bytes large. No terminating null appended.
+static void encodeBase64StringEntry(char *Buffer, uint64_t Value) {
+  assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
+         "Illegal section name encoding for value");
+
+  static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                                 "abcdefghijklmnopqrstuvwxyz"
+                                 "0123456789+/";
+
+  Buffer[0] = '/';
+  Buffer[1] = '/';
+
+  char *Ptr = Buffer + 7;
+  for (unsigned i = 0; i < 6; ++i) {
+    unsigned Rem = Value % 64;
+    Value /= 64;
+    *(Ptr--) = Alphabet[Rem];
+  }
+}
+
+bool llvm::COFF::encodeSectionName(char *Out, uint64_t Offset) {
+  if (Offset <= Max7DecimalOffset) {
+    // Offsets of 7 digits or less are encoded in ASCII.
+    SmallVector<char, COFF::NameSize> Buffer;
+    Twine('/').concat(Twine(Offset)).toVector(Buffer);
+    assert(Buffer.size() <= COFF::NameSize && Buffer.size() >= 2);
+    std::memcpy(Out, Buffer.data(), Buffer.size());
+    return true;
+  }
+
+  if (Offset <= MaxBase64Offset) {
+    // Starting with 10,000,000, offsets are encoded as base64.
+    encodeBase64StringEntry(Out, Offset);
+    return true;
+  }
+
+  // The offset is too large to be encoded.
+  return false;
+}
diff --git a/llvm/lib/MC/WinCOFFObjectWriter.cpp b/llvm/lib/MC/WinCOFFObjectWriter.cpp
--- a/llvm/lib/MC/WinCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/WinCOFFObjectWriter.cpp
@@ -451,32 +451,6 @@
   Sym->MC = &MCSym;
 }
 
-// Maximum offsets for different string table entry encodings.
-enum : unsigned { Max7DecimalOffset = 9999999U };
-enum : uint64_t { MaxBase64Offset = 0xFFFFFFFFFULL }; // 64^6, including 0
-
-// Encode a string table entry offset in base 64, padded to 6 chars, and
-// prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
-// Buffer must be at least 8 bytes large. No terminating null appended.
-static void encodeBase64StringEntry(char *Buffer, uint64_t Value) {
-  assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
-         "Illegal section name encoding for value");
-
-  static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-                                 "abcdefghijklmnopqrstuvwxyz"
-                                 "0123456789+/";
-
-  Buffer[0] = '/';
-  Buffer[1] = '/';
-
-  char *Ptr = Buffer + 7;
-  for (unsigned i = 0; i < 6; ++i) {
-    unsigned Rem = Value % 64;
-    Value /= 64;
-    *(Ptr--) = Alphabet[Rem];
-  }
-}
-
 void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
   if (S.Name.size() <= COFF::NameSize) {
     std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
@@ -484,19 +458,8 @@
   }
 
   uint64_t StringTableEntry = Strings.getOffset(S.Name);
-  if (StringTableEntry <= Max7DecimalOffset) {
-    SmallVector<char, COFF::NameSize> Buffer;
-    Twine('/').concat(Twine(StringTableEntry)).toVector(Buffer);
-    assert(Buffer.size() <= COFF::NameSize && Buffer.size() >= 2);
-    std::memcpy(S.Header.Name, Buffer.data(), Buffer.size());
-    return;
-  }
-  if (StringTableEntry <= MaxBase64Offset) {
-    // Starting with 10,000,000, offsets are encoded as base64.
-    encodeBase64StringEntry(S.Header.Name, StringTableEntry);
-    return;
-  }
-  report_fatal_error("COFF string table is greater than 64 GB.");
+  if (!COFF::encodeSectionName(S.Header.Name, StringTableEntry))
+    report_fatal_error("COFF string table is greater than 64 GB.");
 }
 
 void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {