Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -2919,6 +2919,7 @@
 void MergeSyntheticSection::addSection(MergeInputSection *MS) {
   MS->Parent = this;
   Sections.push_back(MS);
+  Alignment = std::max(Alignment, MS->Alignment);
 }
 
 MergeTailSection::MergeTailSection(StringRef Name, uint32_t Type,
@@ -3063,7 +3064,7 @@
       // Using Entsize in here also allows us to propagate it to the synthetic
       // section.
       return Sec->Name == OutsecName && Sec->Flags == MS->Flags &&
-             Sec->Entsize == MS->Entsize && Sec->Alignment == MS->Alignment;
+             Sec->Entsize == MS->Entsize;
     });
     if (I == MergeSections.end()) {
       MergeSyntheticSection *Syn =
Index: test/ELF/merge-align2.s
===================================================================
--- /dev/null
+++ test/ELF/merge-align2.s
@@ -0,0 +1,25 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
+# RUN: ld.lld -r %t.o -o %t1.o
+# RUN: llvm-readelf -S %t1.o | FileCheck --check-prefix=SEC %s
+# RUN: llvm-readelf -x .cst8 %t1.o | FileCheck %s
+
+## Check that if we have two SHF_MERGE sections with the same name, flags and
+## entsize, but different alignments, we create one single synthetic section,
+## with the larger input alignment as the output alignment.
+
+# SEC: Name  Type     {{.*}} Size   ES Flg Lk Inf Al
+# SEC: .cst8 PROGBITS {{.*}} 000018 08  AM  0   0  8
+
+# CHECK:      0x00000000 02000000 00000000 01000000 00000000
+# CHECK-NEXT: 0x00000010 03000000 00000000
+
+.section .cst8,"aM",@progbits,8,unique,0
+.align 4
+.quad 1
+.quad 2
+
+.section .cst8,"aM",@progbits,8,unique,1
+.align 8
+.quad 1
+.quad 3