Index: llvm/lib/ObjectYAML/ELFEmitter.cpp
===================================================================
--- llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -753,6 +753,11 @@
   for (auto &YamlPhdr : Doc.ProgramHeaders) {
     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
     std::vector<Fragment> Fragments = getPhdrFragments(YamlPhdr, SHeaders);
+    if (!llvm::is_sorted(Fragments, [](const Fragment &A, const Fragment &B) {
+          return A.Offset < B.Offset;
+        }))
+      reportError("sections in the program header with index " +
+                  Twine(PhdrIdx) + " are not sorted by their file offset");
 
     if (YamlPhdr.Offset) {
       PHeader.p_offset = *YamlPhdr.Offset;
Index: llvm/test/tools/llvm-gsymutil/X86/elf-dwarf.yaml
===================================================================
--- llvm/test/tools/llvm-gsymutil/X86/elf-dwarf.yaml
+++ llvm/test/tools/llvm-gsymutil/X86/elf-dwarf.yaml
@@ -395,8 +395,6 @@
       - Section: .note.ABI-tag
       - Section: .note.gnu.build-id
       - Section: .gnu.hash
-      - Section: .dynsym
-      - Section: .dynstr
       - Section: .gnu.version
       - Section: .gnu.version_r
       - Section: .rela.dyn
@@ -409,6 +407,8 @@
       - Section: .rodata
       - Section: .eh_frame_hdr
       - Section: .eh_frame
+      - Section: .dynsym
+      - Section: .dynstr
 Symbols:
   - Name:            .interp
     Type:            STT_SECTION
Index: llvm/test/tools/llvm-readobj/ELF/demangle.test
===================================================================
--- llvm/test/tools/llvm-readobj/ELF/demangle.test
+++ llvm/test/tools/llvm-readobj/ELF/demangle.test
@@ -213,8 +213,8 @@
     Flags: [ PF_R, PF_X ]
     VAddr: 0x0
     Sections:
-      - Section: .dynsym
       - Section: .dynstr
+      - Section: .dynsym
       - Section: .rela.dyn
       - Section: .dynamic
       - Section: .text.foo
Index: llvm/test/tools/llvm-readobj/ELF/hash-symbols.test
===================================================================
--- llvm/test/tools/llvm-readobj/ELF/hash-symbols.test
+++ llvm/test/tools/llvm-readobj/ELF/hash-symbols.test
@@ -298,8 +298,8 @@
     Flags: [ PF_R, PF_X ]
     VAddr: 0x0
     Sections:
-      - Section: .dynsym
       - Section: .dynstr
+      - Section: .dynsym
       - Section: .dynamic
       - Section: .text.foo
   - Type:  PT_DYNAMIC
Index: llvm/test/tools/llvm-readobj/ELF/reloc-negative-addend-no-sym.test
===================================================================
--- llvm/test/tools/llvm-readobj/ELF/reloc-negative-addend-no-sym.test
+++ llvm/test/tools/llvm-readobj/ELF/reloc-negative-addend-no-sym.test
@@ -65,8 +65,8 @@
   - Type: PT_LOAD
     VAddr: 0x1000
     Sections:
-      - Section: .rela.dyn
       - Section: .dynamic
+      - Section: .rela.dyn
   - Type: PT_DYNAMIC
     VAddr: 0x1000
     Sections:
Index: llvm/test/tools/llvm-readobj/ELF/reloc-zero-name-or-value.test
===================================================================
--- llvm/test/tools/llvm-readobj/ELF/reloc-zero-name-or-value.test
+++ llvm/test/tools/llvm-readobj/ELF/reloc-zero-name-or-value.test
@@ -101,8 +101,8 @@
   - Type: PT_LOAD
     VAddr: 0x1000
     Sections:
-      - Section: .rela.dyn
       - Section: .dynamic
+      - Section: .rela.dyn
   - Type: PT_DYNAMIC
     VAddr: 0x1000
     Sections:
Index: llvm/test/tools/obj2yaml/program-headers.yaml
===================================================================
--- llvm/test/tools/obj2yaml/program-headers.yaml
+++ llvm/test/tools/obj2yaml/program-headers.yaml
@@ -414,3 +414,60 @@
     Type:    SHT_PROGBITS
     Flags:   [ SHF_ALLOC ]
     Size:    0x1
+
+## Check that we require sections in a program header
+## declaration to be sorted by the file offset.
+# RUN: not yaml2obj --docnum=5 %s -o %t5 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=UNSORTED --implicit-check-not="error:"
+
+# UNSORTED:      error: sections in the program header with index 1 are not sorted by their file offset
+# UNSORTED-NEXT: error: sections in the program header with index 3 are not sorted by their file offset
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+ProgramHeaders:
+## Case 1: the .bar section is placed after the .foo section in the file.
+##         Check we report an error about the violation of the order.
+  - Type:  PT_LOAD
+    Flags: [ PF_R ]
+    Sections:
+      - Section: .bar
+      - Section: .foo
+    VAddr:  0x1000
+## Case 2: there is nothing wrong with this segment. We have it to show that
+##         we report correct program header indices in error messages.
+  - Type:  PT_LOAD
+    Flags: [ PF_R ]
+    Sections:
+      - Section: .foo
+      - Section: .bar
+    VAddr:  0x1000
+## Case 3: the .bar section is placed before the .zed section in the file,
+##         but the sh_offset of .zed is less than the sh_offset of
+##         the .bar section because of the "ShOffset" property.
+##         Document we report an error for such a case.
+  - Type:  PT_LOAD
+    Flags: [ PF_R ]
+    Sections:
+      - Section: .bar
+      - Section: .zed
+    VAddr:  0x1001
+Sections:
+  - Name:    .foo
+    Type:    SHT_PROGBITS
+    Flags:   [ SHF_ALLOC ]
+    Size:    0x1
+    Address: 0x1000
+  - Name:    .bar
+    Type:    SHT_PROGBITS
+    Flags:   [ SHF_ALLOC ]
+    Size:    0x1
+  - Name:     .zed
+    Type:     SHT_PROGBITS
+    Flags:    [ SHF_ALLOC ]
+    Size:     0x1
+    ShOffset: 0x0