Index: lld/COFF/Writer.cpp
===================================================================
--- lld/COFF/Writer.cpp
+++ lld/COFF/Writer.cpp
@@ -241,6 +241,7 @@
   void addSyntheticIdata();
   void fixPartialSectionChars(StringRef name, uint32_t chars);
   bool fixGnuImportChunks();
+  void fixTlsAlignment();
   PartialSection *createPartialSection(StringRef name, uint32_t outChars);
   PartialSection *findPartialSection(StringRef name, uint32_t outChars);
 
@@ -267,6 +268,7 @@
   DelayLoadContents delayIdata;
   EdataContents edata;
   bool setNoSEHCharacteristic = false;
+  uint32_t tlsAlignment = 0;
 
   DebugDirectoryChunk *debugDirectory = nullptr;
   std::vector<std::pair<COFF::DebugType, Chunk *>> debugRecords;
@@ -633,6 +635,11 @@
   writeSections();
   sortExceptionTable();
 
+  // Fix up the alignment in the TLS Directory's characteristic field,
+  // if a specific alignment value is needed
+  if (tlsAlignment)
+    fixTlsAlignment();
+
   t1.stop();
 
   if (!config->pdbPath.empty() && config->debug) {
@@ -866,6 +873,10 @@
     StringRef name = c->getSectionName();
     if (shouldStripSectionSuffix(sc, name))
       name = name.split('$').first;
+
+    if (name.startswith(".tls"))
+      tlsAlignment = std::max(tlsAlignment, c->getAlignment());
+
     PartialSection *pSec = createPartialSection(name,
                                                 c->getOutputCharacteristics());
     pSec->chunks.push_back(c);
@@ -2038,3 +2049,33 @@
     return it->second;
   return nullptr;
 }
+
+void Writer::fixTlsAlignment() {
+  Defined *tlsSym =
+      dyn_cast_or_null<Defined>(symtab->findUnderscore("_tls_used"));
+  if (!tlsSym)
+    return;
+
+  OutputSection *sec = tlsSym->getChunk()->getOutputSection();
+  assert(sec && tlsSym->getRVA() >= sec->getRVA() &&
+         "no output section for _tls_used");
+
+  uint8_t *secBuf = buffer->getBufferStart() + sec->getFileOff();
+  uint64_t tlsOffset = tlsSym->getRVA() - sec->getRVA();
+  uint64_t directorySize = config->is64()
+                               ? sizeof(object::coff_tls_directory64)
+                               : sizeof(object::coff_tls_directory32);
+
+  if (tlsOffset + directorySize > sec->getRawSize())
+    fatal("_tls_used sym is malformed");
+
+  if (config->is64()) {
+    object::coff_tls_directory64 *tlsDir =
+        reinterpret_cast<object::coff_tls_directory64 *>(&secBuf[tlsOffset]);
+    tlsDir->setAlignment(tlsAlignment);
+  } else {
+    object::coff_tls_directory32 *tlsDir =
+        reinterpret_cast<object::coff_tls_directory32 *>(&secBuf[tlsOffset]);
+    tlsDir->setAlignment(tlsAlignment);
+  }
+}
Index: lld/test/COFF/tls-alignment-32.ll
===================================================================
--- lld/test/COFF/tls-alignment-32.ll
+++ lld/test/COFF/tls-alignment-32.ll
@@ -13,7 +13,8 @@
 ; RUN: llvm-readobj --coff-tls-directory %t.exe | FileCheck %s
 
 ; CHECK: TLSDirectory {
-; CHECK: Characteristics [ (0x0)
+; CHECK: Characteristics [ (0x600000)
+; CHECK-NEXT: IMAGE_SCN_ALIGN_32BYTES (0x600000)
 
 target triple = "i686-pc-windows-msvc"
 
Index: lld/test/COFF/tls-alignment-64.ll
===================================================================
--- lld/test/COFF/tls-alignment-64.ll
+++ lld/test/COFF/tls-alignment-64.ll
@@ -13,7 +13,8 @@
 ; RUN: llvm-readobj --coff-tls-directory %t.exe | FileCheck %s
 
 ; CHECK: TLSDirectory {
-; CHECK: Characteristics [ (0x0)
+; CHECK: Characteristics [ (0x700000)
+; CHECK-NEXT: IMAGE_SCN_ALIGN_64BYTES (0x700000)
 
 target triple = "x86_64-pc-windows-msvc"
 
Index: llvm/include/llvm/Object/COFF.h
===================================================================
--- llvm/include/llvm/Object/COFF.h
+++ llvm/include/llvm/Object/COFF.h
@@ -576,11 +576,22 @@
 
   uint32_t getAlignment() const {
     // Bit [20:24] contains section alignment.
-    uint32_t Shift = (Characteristics & 0x00F00000) >> 20;
+    uint32_t Shift = (Characteristics & COFF::IMAGE_SCN_ALIGN_MASK) >> 20;
     if (Shift > 0)
       return 1U << (Shift - 1);
     return 0;
   }
+
+  void setAlignment(uint32_t Align) {
+    uint32_t AlignBits = 0;
+    if (Align) {
+      assert(llvm::isPowerOf2_32(Align) && "alignment is not a power of 2");
+      assert(llvm::Log2_32(Align) <= 13 && "alignment requested is too large");
+      AlignBits = (llvm::Log2_32(Align) + 1) << 20;
+    }
+    Characteristics =
+        (Characteristics & ~COFF::IMAGE_SCN_ALIGN_MASK) | AlignBits;
+  }
 };
 
 using coff_tls_directory32 = coff_tls_directory<support::little32_t>;