Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -1104,6 +1104,10 @@
   if (!Config->Relocatable)
     addReservedSymbols();
 
+  // Now when we read all script files, we want to finalize order of linker
+  // script commands, which can be not yet final because of INSERT commands.
+  Script->processInsertCommands();
+
   // We want to declare linker script's symbols early,
   // so that we can version them.
   Script->declareSymbols();
Index: ELF/LinkerScript.h
===================================================================
--- ELF/LinkerScript.h
+++ ELF/LinkerScript.h
@@ -267,6 +267,9 @@
   void processSectionCommands();
   void declareSymbols();
 
+  // Used to handle INSERT AFTER statements.
+  void processInsertCommands();
+
   // SECTIONS command list.
   std::vector<BaseCommand *> SectionCommands;
 
@@ -285,6 +288,10 @@
 
   // A list of symbols referenced by the script.
   std::vector<llvm::StringRef> ReferencedSymbols;
+
+  // Used to implement INSERT AFTER. Contains commands that needs
+  // to be inserted into SECTIONS commands list.
+  llvm::DenseMap<StringRef, std::vector<BaseCommand *>> PendingInserts;
 };
 
 extern LinkerScript *Script;
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -165,6 +165,23 @@
   Cmd->Sym = cast<Defined>(Sym);
 }
 
+void LinkerScript::processInsertCommands() {
+  std::vector<BaseCommand *> V;
+  for (BaseCommand *Base : SectionCommands) {
+    V.push_back(Base);
+    if (auto *Cmd = dyn_cast<OutputSection>(Base)) {
+      std::vector<BaseCommand *> &InsertV = PendingInserts[Cmd->Name];
+      V.insert(V.end(), InsertV.begin(), InsertV.end());
+      InsertV.clear();
+    }
+  }
+  for (std::pair<StringRef, std::vector<BaseCommand *>> &P : PendingInserts)
+    if (!P.second.empty())
+      error("unable to INSERT AFTER " + P.first + ": section not defined");
+
+  SectionCommands.swap(V);
+}
+
 // Symbols defined in script should not be inlined by LTO. At the same time
 // we don't know their final values until late stages of link. Here we scan
 // over symbol assignment commands and create placeholder symbols if needed.
Index: ELF/ScriptParser.cpp
===================================================================
--- ELF/ScriptParser.cpp
+++ ELF/ScriptParser.cpp
@@ -446,6 +446,7 @@
   Config->SingleRoRx = true;
 
   expect("{");
+  std::vector<BaseCommand *> V;
   while (!errorCount() && !consume("}")) {
     StringRef Tok = next();
     BaseCommand *Cmd = readProvideOrAssignment(Tok);
@@ -455,8 +456,18 @@
       else
         Cmd = readOutputSectionDescription(Tok);
     }
-    Script->SectionCommands.push_back(Cmd);
+    V.push_back(Cmd);
   }
+
+  if (atEOF() || !consume("INSERT")) {
+    Script->SectionCommands.insert(Script->SectionCommands.end(), V.begin(),
+                                   V.end());
+    return;
+  }
+
+  consume("AFTER");
+  std::vector<BaseCommand *> &Dest = Script->PendingInserts[next()];
+  Dest.insert(Dest.end(), V.begin(), V.end());
 }
 
 static int precedence(StringRef Op) {
Index: test/ELF/insert-after.s
===================================================================
--- test/ELF/insert-after.s
+++ test/ELF/insert-after.s
@@ -0,0 +1,41 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
+
+# RUN: echo "SECTIONS {               \
+# RUN:   .foo.data : { *(.foo.data) } \
+# RUN:  } INSERT AFTER .data;         \
+# RUN:  SECTIONS {                    \
+# RUN:   .foo.text : { *(.foo.text) } \
+# RUN:  } INSERT AFTER .text;" > %tinsert.script
+
+# RUN: echo "SECTIONS {          \
+# RUN:   .text  : { *(.text.*) } \
+# RUN:   .data  : { *(.data.*) } \
+# RUN:  }" > %tmain.script
+
+# RUN: ld.lld %t1.o -o %t1 --script %tinsert.script %tmain.script
+# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
+# CHECK:      Sections:
+# CHECK-NEXT: Idx Name          Size      Address          Type
+# CHECK-NEXT:   0               00000000 0000000000000000
+# CHECK-NEXT:   1 .text         00000008 0000000000000000 TEXT DATA
+# CHECK-NEXT:   2 .foo.text     00000008 0000000000000008 TEXT DATA
+# CHECK-NEXT:   3 .data         00000008 0000000000000010 DATA
+# CHECK-NEXT:   4 .foo.data     00000008 0000000000000018 DATA
+
+# RUN: not ld.lld %t1.o -o %t1 --script %tinsert.script 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=ERR
+# ERR-DAG: error: unable to INSERT AFTER .text: section not defined
+# ERR-DAG: error: unable to INSERT AFTER .data: section not defined
+
+.section .foo.text,"ax"
+.quad 0
+
+.section .foo.data,"aw"
+.quad 0
+
+.section .text.foo,"ax"
+.quad 0
+
+.section .data.foo,"aw"
+.quad 0