Index: llvm/test/tools/llvm-objcopy/COFF/set-section-flags.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objcopy/COFF/set-section-flags.test
@@ -0,0 +1,82 @@
+# RUN: yaml2obj %s -o %t
+
+# Single flag on a section with no flags:
+# RUN: llvm-objcopy --set-section-flags=.foo=alloc %t %t.alloc
+# RUN: llvm-readobj --sections %t.alloc | FileCheck %s --check-prefixes=CHECK,UNINITDATA,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=load %t %t.load
+# RUN: llvm-readobj --sections %t.load | FileCheck %s --check-prefixes=CHECK,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=noload %t %t.noload
+# RUN: llvm-readobj --sections %t.noload | FileCheck %s --check-prefixes=CHECK,READ,WRITE,REMOVE
+# RUN: llvm-objcopy --set-section-flags=.foo=readonly %t %t.readonly
+# RUN: llvm-readobj --sections %t.readonly | FileCheck %s --check-prefixes=CHECK,READ
+# RUN: llvm-objcopy --set-section-flags=.foo=exclude %t %t.exclude
+# RUN: llvm-readobj --sections %t.exclude | FileCheck %s --check-prefixes=CHECK,READ,WRITE,REMOVE
+# RUN: llvm-objcopy --set-section-flags=.foo=debug %t %t.debug
+# RUN: llvm-readobj --sections %t.debug | FileCheck %s --check-prefixes=CHECK,INITDATA,DISCARDABLE,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=code %t %t.code
+# RUN: llvm-readobj --sections %t.code | FileCheck %s --check-prefixes=CHECK,CODE,EXECUTE,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=data %t %t.data
+# RUN: llvm-readobj --sections %t.data | FileCheck %s --check-prefixes=CHECK,INITDATA,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=rom %t %t.rom
+# RUN: llvm-readobj --sections %t.rom | FileCheck %s --check-prefixes=CHECK,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=contents %t %t.contents
+# RUN: llvm-readobj --sections %t.contents | FileCheck %s --check-prefixes=CHECK,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=merge %t %t.merge
+# RUN: llvm-readobj --sections %t.merge | FileCheck %s --check-prefixes=CHECK,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=strings %t %t.strings
+# RUN: llvm-readobj --sections %t.strings | FileCheck %s --check-prefixes=CHECK,READ,WRITE
+# RUN: llvm-objcopy --set-section-flags=.foo=share %t %t.share
+# RUN: llvm-readobj --sections %t.share | FileCheck %s --check-prefixes=CHECK,READ,SHARED,WRITE
+
+# Multiple flags:
+# RUN: llvm-objcopy --set-section-flags=.foo=alloc,readonly,share %t %t.alloc_ro_share
+# RUN: llvm-readobj --sections %t.alloc_ro_share | FileCheck %s --check-prefixes=CHECK,UNINITDATA,READ,SHARED
+# RUN: llvm-objcopy --set-section-flags=.foo=alloc,code %t %t.alloc_code
+# RUN: llvm-readobj --sections %t.alloc_code | FileCheck %s --check-prefixes=CHECK,CODE,UNINITDATA,EXECUTE,READ,WRITE
+
+# Invalid flags:
+# RUN: not llvm-objcopy --set-section-flags=.foo=xyzzy %t %t.xyzzy 2>&1 | FileCheck %s --check-prefix=BAD-FLAG
+
+# Bad flag format:
+# RUN: not llvm-objcopy --set-section-flags=.foo %t %t2 2>&1 | FileCheck %s --check-prefix=BAD-FORMAT
+
+# Setting flags for the same section multiple times:
+# RUN: not llvm-objcopy --set-section-flags=.foo=alloc --set-section-flags=.foo=load %t %t2 2>&1 | FileCheck %s --check-prefix=MULTIPLE-SETS
+
+# Upper-case flags:
+# RUN: llvm-objcopy --set-section-flags=.foo=ALLOC,LOAD,NOLOAD,READONLY,DEBUG,CODE,DATA,ROM,CONTENTS,MERGE,STRINGS,SHARE %t %t.upper
+# RUN: llvm-readobj --sections %t.upper | FileCheck %s --check-prefixes=CHECK,CODE,INITDATA,REMOVE,DISCARDABLE,EXECUTE,READ,SHARED
+
+# Mixed-case flags:
+# RUN: llvm-objcopy --set-section-flags=.foo=aLlOc,LoAd,NoLoad,rEAdONly,Debug,codE,DaTa,rOm,CoNtEnTs,mErGe,sTRINGs,SharE %t %t.mixed
+# RUN: llvm-readobj --sections %t.mixed | FileCheck %s --check-prefixes=CHECK,CODE,INITDATA,REMOVE,DISCARDABLE,EXECUTE,READ,SHARED
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [ ]
+sections:
+  - Name:            .foo
+    Characteristics: [ ]
+    Alignment:       4
+symbols:
+...
+
+# CHECK:            Name: .foo
+# CHECK:            Characteristics [
+# CHECK-NEXT:         IMAGE_SCN_ALIGN_4BYTES
+# CODE-NEXT:          IMAGE_SCN_CNT_CODE
+# INITDATA-NEXT:      IMAGE_SCN_CNT_INITIALIZED_DATA
+# UNINITDATA-NEXT:    IMAGE_SCN_CNT_UNINITIALIZED_DATA
+# REMOVE-NEXT:        IMAGE_SCN_LNK_REMOVE
+# DISCARDABLE-NEXT:   IMAGE_SCN_MEM_DISCARDABLE
+# EXECUTE-NEXT:       IMAGE_SCN_MEM_EXECUTE
+# READ-NEXT:          IMAGE_SCN_MEM_READ
+# SHARED-NEXT:        IMAGE_SCN_MEM_SHARED
+# WRITE-NEXT:         IMAGE_SCN_MEM_WRITE
+# CHECK-NEXT:       ]
+
+# BAD-FORMAT: bad format for --set-section-flags: missing '='
+# MULTIPLE-SETS: --set-section-flags set multiple times for section '.foo'
+
+# BAD-FLAG: unrecognized section flag 'xyzzy'. Flags supported for GNU compatibility: alloc, load, noload, readonly, exclude, debug, code, data, rom, share, contents, merge, strings
Index: llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
===================================================================
--- llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
+++ llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
@@ -89,6 +89,44 @@
                  IMAGE_SCN_MEM_DISCARDABLE);
 }
 
+static void setSectionFlags(Section &Sec, SectionFlag AllFlags) {
+  // Need to preserve existing flags like linker info or alignment settings.
+  const uint32_t PreserveMask =
+      IMAGE_SCN_LNK_INFO | IMAGE_SCN_LNK_COMDAT | IMAGE_SCN_LNK_NRELOC_OVFL |
+      IMAGE_SCN_ALIGN_1BYTES | IMAGE_SCN_ALIGN_2BYTES | IMAGE_SCN_ALIGN_4BYTES |
+      IMAGE_SCN_ALIGN_8BYTES | IMAGE_SCN_ALIGN_16BYTES |
+      IMAGE_SCN_ALIGN_32BYTES | IMAGE_SCN_ALIGN_64BYTES |
+      IMAGE_SCN_ALIGN_128BYTES | IMAGE_SCN_ALIGN_256BYTES |
+      IMAGE_SCN_ALIGN_512BYTES | IMAGE_SCN_ALIGN_1024BYTES |
+      IMAGE_SCN_ALIGN_2048BYTES | IMAGE_SCN_ALIGN_4096BYTES |
+      IMAGE_SCN_ALIGN_8192BYTES;
+
+  // Setup new section characteristics based on the flags provided in command
+  // line.
+  uint32_t NewCharacteristics =
+      (Sec.Header.Characteristics & PreserveMask) | IMAGE_SCN_MEM_READ;
+
+  if ((AllFlags & SectionFlag::SecAlloc) && !(AllFlags & SectionFlag::SecLoad))
+    NewCharacteristics |= IMAGE_SCN_CNT_UNINITIALIZED_DATA;
+  if (AllFlags & SectionFlag::SecNoload)
+    NewCharacteristics |= IMAGE_SCN_LNK_REMOVE;
+  if (!(AllFlags & SectionFlag::SecReadonly))
+    NewCharacteristics |= IMAGE_SCN_MEM_WRITE;
+  if (AllFlags & SectionFlag::SecDebug)
+    NewCharacteristics |=
+        IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_DISCARDABLE;
+  if (AllFlags & SectionFlag::SecCode)
+    NewCharacteristics |= IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE;
+  if (AllFlags & SectionFlag::SecData)
+    NewCharacteristics |= IMAGE_SCN_CNT_INITIALIZED_DATA;
+  if (AllFlags & SectionFlag::SecShare)
+    NewCharacteristics |= IMAGE_SCN_MEM_SHARED;
+  if (AllFlags & SectionFlag::SecExclude)
+    NewCharacteristics |= IMAGE_SCN_LNK_REMOVE;
+
+  Sec.Header.Characteristics = NewCharacteristics;
+}
+
 static Error handleArgs(const CopyConfig &Config, Object &Obj) {
   // Perform the actual section removals.
   Obj.removeSections([&Config](const Section &Sec) {
@@ -178,6 +216,13 @@
     return false;
   });
 
+  if (!Config.SetSectionFlags.empty())
+    for (Section &Sec : Obj.getMutableSections()) {
+      const auto It = Config.SetSectionFlags.find(Sec.Name);
+      if (It != Config.SetSectionFlags.end())
+        setSectionFlags(Sec, It->second.NewFlags);
+    }
+
   for (const auto &Flag : Config.AddSection) {
     StringRef SecName, FileName;
     std::tie(SecName, FileName) = Flag.split("=");
@@ -205,10 +250,10 @@
       !Config.SymbolsToGlobalize.empty() || !Config.SymbolsToKeep.empty() ||
       !Config.SymbolsToLocalize.empty() || !Config.SymbolsToWeaken.empty() ||
       !Config.SymbolsToKeepGlobal.empty() || !Config.SectionsToRename.empty() ||
-      !Config.SetSectionAlignment.empty() || !Config.SetSectionFlags.empty() ||
-      Config.ExtractDWO || Config.KeepFileSymbols || Config.LocalizeHidden ||
-      Config.PreserveDates || Config.StripDWO || Config.StripNonAlloc ||
-      Config.StripSections || Config.Weaken || Config.DecompressDebugSections ||
+      !Config.SetSectionAlignment.empty() || Config.ExtractDWO ||
+      Config.KeepFileSymbols || Config.LocalizeHidden || Config.PreserveDates ||
+      Config.StripDWO || Config.StripNonAlloc || Config.StripSections ||
+      Config.Weaken || Config.DecompressDebugSections ||
       Config.DiscardMode == DiscardType::Locals ||
       !Config.SymbolsToAdd.empty() || Config.EntryExpr) {
     return createStringError(llvm::errc::invalid_argument,