Index: llvm/test/tools/obj2yaml/elf-output-indentation.yaml
===================================================================
--- /dev/null
+++ llvm/test/tools/obj2yaml/elf-output-indentation.yaml
@@ -0,0 +1,77 @@
+## obj2yaml tries to optimize indentations between keys and
+## values to make an output nicer.
+## In this test we demonstrate the output produced.
+
+# RUN: yaml2obj %s -o %t
+# RUN: obj2yaml %t | FileCheck %s --strict-whitespace --match-full-lines
+
+#      CHECK:--- !ELF
+# CHECK-NEXT:FileHeader:
+# CHECK-NEXT:  Class:   ELFCLASS64
+# CHECK-NEXT:  Data:    ELFDATA2LSB
+# CHECK-NEXT:  Type:    ET_REL
+# CHECK-NEXT:  Machine: EM_X86_64
+# CHECK-NEXT:Sections:
+# CHECK-NEXT:  - Name: .text
+# CHECK-NEXT:    Type: SHT_PROGBITS
+# CHECK-NEXT:  - Name:         .data
+# CHECK-NEXT:    Type:         SHT_PROGBITS
+# CHECK-NEXT:    AddressAlign: 0x0000000000000001
+# CHECK-NEXT:  - Name:    .rela.text
+# CHECK-NEXT:    Type:    SHT_RELA
+# CHECK-NEXT:    Link:    .symtab
+# CHECK-NEXT:    EntSize: 0x0000000000000018
+# CHECK-NEXT:    Info:    .text
+# CHECK-NEXT:    Relocations:
+# CHECK-NEXT:      - Offset: 0x0000000000000000
+# CHECK-NEXT:        Type:   R_X86_64_PC32
+# CHECK-NEXT:  - Name:    .rela.text2
+# CHECK-NEXT:    Type:    SHT_RELA
+# CHECK-NEXT:    Link:    .symtab
+# CHECK-NEXT:    EntSize: 0x0000000000000018
+# CHECK-NEXT:Symbols: []
+# CHECK-NEXT:DynamicSymbols:
+# CHECK-NEXT:  - Name:    dynamic
+# CHECK-NEXT:    Binding: STB_GLOBAL
+# CHECK-NEXT:    Value:   0x0000000012345678
+# CHECK-NEXT:  - Name: both
+# CHECK-NEXT:...
+
+## Use an arbitrary YAML with different fields.
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name: .text
+    Type: SHT_PROGBITS
+  - Name: .data
+    Type: SHT_PROGBITS
+    AddressAlign: 0x1
+  - Name:    .rela.text
+    Type:    SHT_RELA
+    Link:    .symtab
+    EntSize: 0x0000000000000018
+    Info:    .text
+    Relocations:
+      - Offset: 0x0000000000000000
+        Type:   R_X86_64_PC32
+  - Name:    .rela.text2
+    Type:    SHT_RELA
+    Link:    .symtab
+    EntSize: 0x0000000000000018
+    Relocations: []
+ProgramHeaders:
+  - Type:  PT_LOAD
+    VAddr: 0x100
+    Sections:
+      - Section: .text
+Symbols: []
+DynamicSymbols:
+  - Name:    dynamic
+    Binding: STB_GLOBAL
+    Value:   0x0000000012345678
+  - Name:  both
Index: llvm/tools/obj2yaml/obj2yaml.cpp
===================================================================
--- llvm/tools/obj2yaml/obj2yaml.cpp
+++ llvm/tools/obj2yaml/obj2yaml.cpp
@@ -17,6 +17,51 @@
 using namespace llvm;
 using namespace llvm::object;
 
+std::string postProcess(StringRef In) {
+  struct LineInfo {
+    size_t KeyLen;
+    size_t Colon;
+    StringRef Line;
+  };
+
+  struct ScanState {
+    size_t MaxKey = 0;
+    std::vector<LineInfo> Lines;
+  } State;
+
+  std::string Out;
+  auto FlushState = [&]() {
+    for (const LineInfo &LI : State.Lines) {
+      Out += LI.Line.take_front(LI.Colon + 1).str();
+      Out += std::string(State.MaxKey - LI.KeyLen + 1, ' ');
+      Out += LI.Line.drop_front(LI.Colon + 1).ltrim(' ');
+      Out += '\n';
+    }
+    State = {};
+  };
+
+  SmallVector<StringRef, 32> Lines;
+  In.split(Lines, '\n');
+
+  for (StringRef Line : Lines) {
+    size_t Colon = Line.find(':');
+    if (Colon == StringRef::npos || Colon == Line.size() - 1) {
+      FlushState();
+      Out += Line.str() + '\n';
+      continue;
+    }
+
+    if (Line.find('-') != StringRef::npos)
+      FlushState();
+
+    StringRef Key = Line.take_front(Colon).ltrim("- ");
+    if (Key.size() > State.MaxKey)
+      State.MaxKey = Key.size();
+    State.Lines.push_back({Key.size(), Colon, Line});
+  }
+  return Out;
+}
+
 static Error dumpObject(const ObjectFile &Obj) {
   if (Obj.isCOFF())
     return errorCodeToError(coff2yaml(outs(), cast<COFFObjectFile>(Obj)));
@@ -24,8 +69,15 @@
   if (Obj.isXCOFF())
     return errorCodeToError(xcoff2yaml(outs(), cast<XCOFFObjectFile>(Obj)));
 
-  if (Obj.isELF())
-    return elf2yaml(outs(), Obj);
+  if (Obj.isELF()) {
+    SmallString<0> Storage;
+    raw_svector_ostream OS(Storage);
+    if (Error Err = elf2yaml(OS, Obj))
+      return Err;
+    std::string Formatted = postProcess(Storage);
+    outs().write(Formatted.data(), Formatted.size());
+    return Error::success();
+  }
 
   if (Obj.isWasm())
     return errorCodeToError(wasm2yaml(outs(), cast<WasmObjectFile>(Obj)));