diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -180,6 +180,7 @@
   std::string MapFile;
 
   uint64_t ImageBase = -1;
+  uint64_t FileAlign = 512;
   uint64_t StackReserve = 1024 * 1024;
   uint64_t StackCommit = 4096;
   uint64_t HeapReserve = 1024 * 1024;
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -1186,6 +1186,13 @@
   if (auto *Arg = Args.getLastArg(OPT_base))
     parseNumbers(Arg->getValue(), &Config->ImageBase);
 
+  // Handle /filealign
+  if (auto *Arg = Args.getLastArg(OPT_filealign)) {
+    parseNumbers(Arg->getValue(), &Config->FileAlign);
+    if (!isPowerOf2_64(Config->FileAlign))
+      error("/filealign: not a power of two: " + Twine(Config->FileAlign));
+  }
+
   // Handle /stack
   if (auto *Arg = Args.getLastArg(OPT_stack))
     parseNumbers(Arg->getValue(), &Config->StackReserve, &Config->StackCommit);
diff --git a/lld/COFF/Options.td b/lld/COFF/Options.td
--- a/lld/COFF/Options.td
+++ b/lld/COFF/Options.td
@@ -32,6 +32,7 @@
 def export  : P<"export", "Export a function">;
 // No help text because /failifmismatch is not intended to be used by the user.
 def failifmismatch : P<"failifmismatch", "">;
+def filealign : P<"filealign", "Section alignment in the output file">;
 def functionpadmin : F<"functionpadmin">;
 def functionpadmin_opt : P<"functionpadmin", "Prepares an image for hotpatching">;
 def guard   : P<"guard", "Control flow guard">;
diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -73,7 +73,6 @@
 static_assert(sizeof(DOSProgram) % 8 == 0,
               "DOSProgram size must be multiple of 8");
 
-static const int SectorSize = 512;
 static const int DOSStubSize = sizeof(dos_header) + sizeof(DOSProgram);
 static_assert(DOSStubSize % 8 == 0, "DOSStub size must be multiple of 8");
 
@@ -1096,7 +1095,7 @@
   PointerToSymbolTable = FileOff;
   FileOff += OutputSymtab.size() * sizeof(coff_symbol16);
   FileOff += 4 + Strtab.size();
-  FileSize = alignTo(FileOff, SectorSize);
+  FileSize = alignTo(FileOff, Config->FileAlign);
 }
 
 void Writer::mergeSections() {
@@ -1138,7 +1137,7 @@
                   sizeof(coff_section) * OutputSections.size();
   SizeOfHeaders +=
       Config->is64() ? sizeof(pe32plus_header) : sizeof(pe32_header);
-  SizeOfHeaders = alignTo(SizeOfHeaders, SectorSize);
+  SizeOfHeaders = alignTo(SizeOfHeaders, Config->FileAlign);
   uint64_t RVA = PageSize; // The first page is kept unmapped.
   FileSize = SizeOfHeaders;
 
@@ -1164,7 +1163,7 @@
       C->finalizeContents();
       VirtualSize += C->getSize();
       if (C->hasData())
-        RawSize = alignTo(VirtualSize, SectorSize);
+        RawSize = alignTo(VirtualSize, Config->FileAlign);
     }
     if (VirtualSize > UINT32_MAX)
       error("section larger than 4 GiB: " + Sec->Name);
@@ -1173,7 +1172,7 @@
     if (RawSize != 0)
       Sec->Header.PointerToRawData = FileSize;
     RVA += alignTo(VirtualSize, PageSize);
-    FileSize += alignTo(RawSize, SectorSize);
+    FileSize += alignTo(RawSize, Config->FileAlign);
   }
   SizeOfImage = alignTo(RVA, PageSize);
 }
@@ -1240,7 +1239,7 @@
 
   PE->ImageBase = Config->ImageBase;
   PE->SectionAlignment = PageSize;
-  PE->FileAlignment = SectorSize;
+  PE->FileAlignment = Config->FileAlign;
   PE->MajorImageVersion = Config->MajorImageVersion;
   PE->MinorImageVersion = Config->MinorImageVersion;
   PE->MajorOperatingSystemVersion = Config->MajorOSVersion;
diff --git a/lld/test/COFF/filealign.test b/lld/test/COFF/filealign.test
new file mode 100644
--- /dev/null
+++ b/lld/test/COFF/filealign.test
@@ -0,0 +1,51 @@
+# RUN: yaml2obj < %s > %t.obj
+
+# RUN: lld-link /out:%t.exe /entry:main %t.obj
+# RUN: llvm-readobj --file-headers %t.exe | FileCheck -check-prefix=DEFAULT-HEADER %s
+
+# DEFAULT-HEADER:    FileAlignment: 512
+
+# RUN: lld-link /out:%t.exe /entry:main %t.obj /filealign:4096
+# RUN: llvm-readobj --file-headers %t.exe | FileCheck -check-prefix=FILEALIGN-HEADER %s
+
+# FILEALIGN-HEADER: FileAlignment: 4096
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4096
+    SectionData:     0000000000000000
+    Relocations:
+      - VirtualAddress:  0
+        SymbolName:      __ImageBase
+        Type:            IMAGE_REL_AMD64_ADDR64
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          0
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            __ImageBase
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...