Index: llvm/trunk/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test
===================================================================
--- llvm/trunk/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test
+++ llvm/trunk/test/tools/llvm-objcopy/ELF/group-addr-misaligned.test
@@ -0,0 +1,38 @@
+# RUN: yaml2obj %s > %t
+# RUN: not llvm-objcopy %t %t2 2>&1 | FileCheck %s
+# CHECK: error: Invalid alignment 1 of group section .group.
+
+# In this test, we check that llvm-objcopy reports an error
+# for SHT_GROUP section with invalid alignment (not a multiple of 4). 
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+## It is not important for passing the test case to have this placeholder,
+## but having it would trigger ubsan failure when writing the group section
+## into a file if the error tested would not be reported by llvm-objcopy.
+  - Name:            .placeholder
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000001
+    Content:         "00"
+  - Name:            .group
+    Type:            SHT_GROUP
+    Link:            .symtab
+    AddressAlign:    0x0000000000000001
+    Info:            foo
+    Members:
+      - SectionOrType:   GRP_COMDAT
+      - SectionOrType:   .text.foo
+  - Name:            .text.foo
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR, SHF_GROUP ]
+    AddressAlign:    0x0000000000000001
+Symbols:
+  Local:
+    - Name:            foo
+      Section:         .group
Index: llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp
===================================================================
--- llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp
+++ llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp
@@ -949,6 +949,9 @@
 
 template <class ELFT>
 void ELFBuilder<ELFT>::initGroupSection(GroupSection *GroupSec) {
+  if (GroupSec->Align % sizeof(ELF::Elf32_Word) != 0)
+    error("Invalid alignment " + Twine(GroupSec->Align) + " of group section " +
+          GroupSec->Name);
   auto SecTable = Obj.sections();
   auto SymTab = SecTable.template getSectionOfType<SymbolTableSection>(
       GroupSec->Link,