Index: ELF/InputSection.h
===================================================================
--- ELF/InputSection.h
+++ ELF/InputSection.h
@@ -318,8 +318,10 @@
 
   OutputSection *getParent() const;
 
-  // The offset from beginning of the output sections this section was assigned
-  // to. The writer sets a value.
+  // This variable has two usages. Initially, it represents an index in the
+  // OutputSection's InputSection list, and is used when ordering SHF_LINK_ORDER
+  // sections. After assignAddresses is called, it represents the offset from
+  // the beginning of the output section this section was assigned to.
   uint64_t OutSecOff = 0;
 
   static bool classof(const SectionBase *S);
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -674,6 +674,11 @@
   if (Ctx->OutSec->Flags & SHF_COMPRESSED)
     return;
 
+  // The Size previously denoted how many InputSections had been added to this
+  // section, and was used for sorting SHF_LINK_ORDER sections. Reset it to
+  // compute the actual size value.
+  Sec->Size = 0;
+
   // We visited SectionsCommands from processSectionCommands to
   // layout sections. Now, we visit SectionsCommands again to fix
   // section offsets.
Index: ELF/OutputSections.h
===================================================================
--- ELF/OutputSections.h
+++ ELF/OutputSections.h
@@ -71,8 +71,12 @@
   // it may have a non-null value.
   OutputSection *RelocationSection = nullptr;
 
-  // The following fields correspond to Elf_Shdr members.
+  // Initially this field is the number of InputSections that have been added to
+  // the OutputSection so far. Later on, after a call to assignAddresses, it
+  // corresponds to the Elf_Shdr member.
   uint64_t Size = 0;
+
+  // The following fields correspond to Elf_Shdr members.
   uint64_t Offset = 0;
   uint64_t LMAOffset = 0;
   uint64_t Addr = 0;
Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -116,13 +116,7 @@
   IS->Parent = this;
   Flags |= IS->Flags;
   Alignment = std::max(Alignment, IS->Alignment);
-
-  // The actual offsets will be computed by assignAddresses. For now, use
-  // crude approximation so that it is at least easy for other code to know the
-  // section order. It is also used to calculate the output section size early
-  // for compressed debug sections.
-  IS->OutSecOff = alignTo(Size, IS->Alignment);
-  this->Size = IS->OutSecOff + IS->getSize();
+  IS->OutSecOff = Size++;
 
   // If this section contains a table of fixed-size entries, sh_entsize
   // holds the element size. If it contains elements of different size we
@@ -189,6 +183,15 @@
       !Name.startswith(".debug_"))
     return;
 
+  // Calculate the section offsets and size pre-compression.
+  Size = 0;
+  for (BaseCommand *Cmd : SectionCommands)
+    if (auto *ISD = dyn_cast<InputSectionDescription>(Cmd))
+      for (InputSection *IS : ISD->Sections) {
+        IS->OutSecOff = alignTo(Size, IS->Alignment);
+        this->Size = IS->OutSecOff + IS->getSize();
+      }
+
   // Create a section header.
   ZDebugHeader.resize(sizeof(Elf_Chdr));
   auto *Hdr = reinterpret_cast<Elf_Chdr *>(ZDebugHeader.data());
Index: test/ELF/linkerscript/unused-synthetic.s
===================================================================
--- test/ELF/linkerscript/unused-synthetic.s
+++ test/ELF/linkerscript/unused-synthetic.s
@@ -13,6 +13,16 @@
 # CHECK:      .text
 # CHECK-NEXT: .dynsym
 
+# Test that the size of a removed unused synthetic input section is not added
+# to the output section size. Adding a symbol assignment prevents removal of
+# the output section, but does not cause the section size to be recomputed.
+# RUN: echo "SECTIONS { \
+# RUN:    .got.plt : { a_sym = .; *(.got.plt) } \
+# RUN:  }" > %t2.script
+# RUN: ld.lld -shared -o %t2.so --script %t2.script %t.o
+# RUN: llvm-objdump -section-headers %t2.so | FileCheck %s --check-prefix=CHECK2
+# CHECK2: .got.plt 00000000
+
 .global _start
 _start:
   nop