Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -128,6 +128,7 @@
   bool ICF;
   bool MipsN32Abi = false;
   bool NoGnuUnique;
+  bool NoinhibitExec;
   bool NoUndefinedVersion;
   bool Nostdlib;
   bool OFormatBinary;
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -647,6 +647,7 @@
   Config->LTOPartitions = getInteger(Args, OPT_lto_partitions, 1);
   Config->MapFile = Args.getLastArgValue(OPT_Map);
   Config->NoGnuUnique = Args.hasArg(OPT_no_gnu_unique);
+  Config->NoinhibitExec = Args.hasArg(OPT_noinhibit_exec);
   Config->NoUndefinedVersion = Args.hasArg(OPT_no_undefined_version);
   Config->Nostdlib = Args.hasArg(OPT_nostdlib);
   Config->OFormatBinary = isOutputFormatBinary(Args);
Index: ELF/Relocations.cpp
===================================================================
--- ELF/Relocations.cpp
+++ ELF/Relocations.cpp
@@ -535,6 +535,13 @@
   In<ELFT>::RelaDyn->addReloc({Target->CopyRel, Sec, Off, false, SS, 0});
 }
 
+static void errorOrWarn(const Twine &Msg) {
+  if (!Config->NoinhibitExec)
+    error(Msg);
+  else
+    warn(Msg);
+}
+
 template <class ELFT>
 static RelExpr adjustExpr(SymbolBody &Body, RelExpr Expr, uint32_t Type,
                           const uint8_t *Data, InputSectionBase &S,
@@ -609,8 +616,8 @@
     return toPlt(Expr);
   }
 
-  error("symbol '" + toString(Body) + "' defined in " + toString(Body.File) +
-        " has no type");
+  errorOrWarn("symbol '" + toString(Body) + "' defined in " +
+              toString(Body.File) + " has no type");
   return Expr;
 }
 
@@ -678,8 +685,7 @@
   if (Config->UnresolvedSymbols == UnresolvedPolicy::IgnoreAll)
     return;
 
-  bool CanBeExternal = Sym.symbol()->computeBinding() != STB_LOCAL &&
-                       Sym.getVisibility() == STV_DEFAULT;
+  bool CanBeExternal = Sym.symbol()->canBeExternal();
   if (Config->UnresolvedSymbols == UnresolvedPolicy::Ignore && CanBeExternal)
     return;
 
@@ -905,9 +911,10 @@
       // We don't know anything about the finaly symbol. Just ask the dynamic
       // linker to handle the relocation for us.
       if (!Target->isPicRel(Type))
-        error("relocation " + toString(Type) +
-              " cannot be used against shared object; recompile with -fPIC" +
-              getLocation<ELFT>(Sec, Body, Offset));
+        errorOrWarn(
+            "relocation " + toString(Type) +
+            " cannot be used against shared object; recompile with -fPIC" +
+            getLocation<ELFT>(Sec, Body, Offset));
 
       In<ELFT>::RelaDyn->addReloc(
           {Target->getDynRel(Type), &Sec, Offset, false, &Body, Addend});
Index: ELF/Symbols.h
===================================================================
--- ELF/Symbols.h
+++ ELF/Symbols.h
@@ -369,6 +369,7 @@
   unsigned InVersionScript : 1;
 
   bool includeInDynsym() const;
+  bool canBeExternal() const;
   uint8_t computeBinding() const;
   bool isWeak() const { return Binding == llvm::ELF::STB_WEAK; }
 
Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -141,10 +141,6 @@
   if (isShared())
     return !NeedsCopy && !NeedsPltAddr;
 
-  // That's all that can be preempted in a non-DSO.
-  if (!Config->Shared)
-    return false;
-
   // Only symbols that appear in dynsym can be preempted.
   if (!symbol()->includeInDynsym())
     return false;
@@ -153,6 +149,12 @@
   if (symbol()->Visibility != STV_DEFAULT)
     return false;
 
+  // Undefined external symbols in a non-DSO usually reported by linker and link
+  // fails, but together with --unresolved-symbols=ignore-all link succeeds and
+  // runtime linker should take care about them during execution.
+  if (!Config->Shared)
+    return isUndefined();
+
   // -Bsymbolic means that definitions are not preempted.
   if (Config->Bsymbolic || (Config->BsymbolicFunctions && isFunc()))
     return !isDefined();
@@ -354,11 +356,21 @@
   return Binding;
 }
 
+bool Symbol::canBeExternal() const {
+  return computeBinding() != STB_LOCAL &&
+         body()->getVisibility() == STV_DEFAULT;
+}
+
 bool Symbol::includeInDynsym() const {
   if (computeBinding() == STB_LOCAL)
     return false;
-  return ExportDynamic || body()->isShared() ||
-         (body()->isUndefined() && Config->Shared);
+  if (ExportDynamic || body()->isShared())
+    return true;
+  if (!body()->isUndefined())
+    return false;
+  if (Config->Shared)
+    return true;
+  return canBeExternal() && !body()->symbol()->isWeak();
 }
 
 // Print out a log message for --trace-symbol.
Index: test/ELF/executable-undefined-ignoreall.s
===================================================================
--- test/ELF/executable-undefined-ignoreall.s
+++ test/ELF/executable-undefined-ignoreall.s
@@ -0,0 +1,13 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: ld.lld %t -o %tout --unresolved-symbols=ignore-all -pie
+# RUN: llvm-readobj -r %tout | FileCheck %s
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section ({{.*}}) .rela.plt {
+# CHECK-NEXT:     0x2018 R_X86_64_JUMP_SLOT foo 0x0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+
+_start:
+callq foo@PLT
Index: test/ELF/no-inhibit-exec.s
===================================================================
--- test/ELF/no-inhibit-exec.s
+++ test/ELF/no-inhibit-exec.s
@@ -6,7 +6,7 @@
 
 # CHECK: Disassembly of section .text:
 # CHECK-NEXT: _start
-# CHECK-NEXT: 201000: {{.*}} callq -2101253
+# CHECK-NEXT: 201000: {{.*}} callq 0
 
 # next code will not link without noinhibit-exec flag
 # because of undefined symbol _bar