Index: llvm/test/tools/llvm-objcopy/ELF/binary-output-empty.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objcopy/ELF/binary-output-empty.test
@@ -0,0 +1,26 @@
+# RUN: yaml2obj %s -o %t.o
+
+# Writing an empty output to a non-existant file will still create it.
+# RUN: rm -f %t-new.txt
+# RUN: llvm-objcopy -R .text -O binary %t.o %t-new.txt
+# RUN: wc -c %t-new.txt | FileCheck %s
+
+# Writing an empty output to an existing file will truncate it.
+# RUN: echo abcd > %t-existing.txt
+# RUN: llvm-objcopy -R .text -O binary %t.o %t-existing.txt
+# RUN: wc -c %t-existing.txt | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Content:         "c3c3c3c3"
+    Size:            0x1000
+
+# CHECK: 0
Index: llvm/tools/llvm-objcopy/Buffer.cpp
===================================================================
--- llvm/tools/llvm-objcopy/Buffer.cpp
+++ llvm/tools/llvm-objcopy/Buffer.cpp
@@ -10,7 +10,9 @@
 #include "Buffer.h"
 #include "llvm-objcopy.h"
 #include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Process.h"
 #include <memory>
 
 namespace llvm {
@@ -19,15 +21,27 @@
 Buffer::~Buffer() {}
 
 void FileBuffer::allocate(size_t Size) {
-  Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
-      FileOutputBuffer::create(getName(), Size, FileOutputBuffer::F_executable);
-  handleAllErrors(BufferOrErr.takeError(), [this](const ErrorInfoBase &E) {
-    error("failed to open " + getName() + ": " + E.message());
-  });
-  Buf = std::move(*BufferOrErr);
+  // Only create a buffer if we have a positive size. Otherwise, create (and
+  // truncate) the file.
+  if (Size > 0) {
+    Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
+        FileOutputBuffer::create(getName(), Size,
+                                 FileOutputBuffer::F_executable);
+    handleAllErrors(BufferOrErr.takeError(), [this](const ErrorInfoBase &E) {
+      error("failed to open " + getName() + ": " + E.message());
+    });
+    Buf = std::move(*BufferOrErr);
+  } else {
+    int FD;
+    if (std::error_code EC = sys::fs::openFileForWrite(
+            getName(), FD, sys::fs::CD_CreateAlways, sys::fs::OF_None))
+      reportError(getName(), EC);
+    if (auto EC = sys::Process::SafelyCloseFileDescriptor(FD))
+      reportError(getName(), EC);
+  }
 }
 
-Error FileBuffer::commit() { return Buf->commit(); }
+Error FileBuffer::commit() { return Buf ? Buf->commit() : Error::success(); }
 
 uint8_t *FileBuffer::getBufferStart() {
   return reinterpret_cast<uint8_t *>(Buf->getBufferStart());