diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -4077,6 +4077,9 @@
       Debug = true;
   }
 
+  if (parseToken(AsmToken::EndOfStatement))
+    return addErrorSuffix(" in '.cfi_sections' directive");
+
   getStreamer().emitCFISections(EH, Debug);
   return false;
 }
@@ -4104,6 +4107,8 @@
 /// parseDirectiveCFIEndProc
 /// ::= .cfi_endproc
 bool AsmParser::parseDirectiveCFIEndProc() {
+  if (parseToken(AsmToken::EndOfStatement))
+    return addErrorSuffix(" in '.cfi_endproc' directive");
   getStreamer().emitCFIEndProc();
   return false;
 }
diff --git a/llvm/test/MC/AsmParser/round-trip.s b/llvm/test/MC/AsmParser/round-trip.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/AsmParser/round-trip.s
@@ -0,0 +1,15 @@
+# RUN: llvm-mc -preserve-comments -triple i386-unknown-unknown %s >%t-1.s
+# RUN: llvm-mc -preserve-comments -triple i386-unknown-unknown %t-1.s >%t-2.s
+# RUN: diff %t-1.s %t-2.s
+
+# Test that various assembly round-trips when run through MC; the first
+# transition from hand-written to "canonical" output may introduce some small
+# differences, so we don't include the initial input in the comparison.
+
+.text
+
+# Some of these CFI instructions didn't consume the end of statement
+# consistently, which led to extra empty lines in the output.
+.cfi_sections .debug_frame
+.cfi_startproc
+.cfi_endproc
diff --git a/llvm/test/MC/ELF/cfi.s b/llvm/test/MC/ELF/cfi.s
--- a/llvm/test/MC/ELF/cfi.s
+++ b/llvm/test/MC/ELF/cfi.s
@@ -1,4 +1,5 @@
 // RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -S --sr --sd - | FileCheck %s
+// RUN: not llvm-mc -triple=x86_64 -o - -defsym=ERR=1 %s 2>&1 | FileCheck %s --check-prefix=ERR
 
 f1:
         .cfi_startproc
@@ -435,3 +436,20 @@
 // CHECK-NEXT:       0x6E4 R_X86_64_PC32 .text 0x21
 // CHECK-NEXT:     ]
 // CHECK:        }
+
+.ifdef ERR
+// ERR: [[#@LINE+1]]:15: error: Expected an identifier
+.cfi_sections $
+// ERR: [[#@LINE+1]]:28: error: unexpected token in '.cfi_sections' directive
+.cfi_sections .debug_frame $
+// ERR: [[#@LINE+1]]:39: error: unexpected token in '.cfi_sections' directive
+.cfi_sections .debug_frame, .eh_frame $
+
+// ERR: [[#@LINE+1]]:16: error: unexpected token in '.cfi_startproc' directive
+.cfi_startproc $
+// ERR: [[#@LINE+1]]:23: error: unexpected token in '.cfi_startproc' directive
+.cfi_startproc simple $
+
+// ERR: [[#@LINE+1]]:14: error: unexpected token in '.cfi_endproc' directive
+.cfi_endproc $
+.endif