diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -432,6 +432,10 @@
 }
 
 void llvm::sys::DefaultOneShotPipeSignalHandler() {
+  // UNIX03 conformance requires a non-zero exit code and an error message
+  // to stderr when writing to a closed stdout fails.
+  errs() << "error: write on a pipe with no reader\n";
+
   // Send a special return code that drivers can check for, from sysexits.h.
   exit(EX_IOERR);
 }
diff --git a/llvm/test/tools/llvm-nm/Inputs/unix03-sigpipe-exit.sh b/llvm/test/tools/llvm-nm/Inputs/unix03-sigpipe-exit.sh
new file mode 100755
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/Inputs/unix03-sigpipe-exit.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+NM_CMD=${1:-$(which nm)}
+exec 3>&1
+(
+	# sleep first, so that true can finish running before nm does.
+	# Because true finishes earlier, stdout for nm will be closed and nm will
+	# receive SIGPIPE signal when writing to or flushing stdout.
+	sleep 2
+	$NM_CMD $(which $NM_CMD)
+	echo exitstatus $? >&3
+) | true
diff --git a/llvm/test/tools/llvm-nm/unix03-sigpipe-exit.test b/llvm/test/tools/llvm-nm/unix03-sigpipe-exit.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-nm/unix03-sigpipe-exit.test
@@ -0,0 +1,11 @@
+# Test that when nm tries to write to a closed stdout it will finish with
+# a non-zero exit code and an error message on stderr.
+# This is required for UNIX03 conformance.
+
+UNSUPPORTED: system-windows
+
+RUN: sh %S/Inputs/unix03-sigpipe-exit.sh llvm-nm > %t.stdout 2> %t.stderr
+RUN: FileCheck --check-prefix=STDOUT --input-file=%t.stdout %s
+RUN: FileCheck --check-prefix=STDERR --input-file=%t.stderr %s
+STDOUT-NOT: exitstatus 0
+STDERR: write on a pipe with no reader