Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -1164,26 +1164,30 @@
 
   unsigned short DisableFlags =
       options::NoDriverOption | options::Unsupported | options::Ignored;
-  // We want to show cc1-only options only when clang is invoked as "clang
-  // -cc1". When clang is invoked as "clang -cc1", we add "#" to the beginning
-  // of an --autocomplete  option so that the clang driver can distinguish
-  // whether it is requested to show cc1-only options or not.
-  if (PassedFlags.size() > 0 && PassedFlags[0] == '#') {
-    DisableFlags &= ~options::NoDriverOption;
-    PassedFlags = PassedFlags.substr(1);
+
+  // Parse PassedFlags by ":" as all the command-line flags are passed to this
+  // function separated by ":"
+  StringRef TargetFlag = PassedFlags;
+  for (; TargetFlag.find(':') != StringRef::npos;) {
+    StringRef CurFlag;
+    std::tie(CurFlag, TargetFlag) = TargetFlag.split(":");
+    // We want to show cc1-only options only when clang is invoked with -cc1 or
+    // -Xclang.
+    if (CurFlag == "-Xclang" || CurFlag == "-cc1")
+      DisableFlags &= ~options::NoDriverOption;
   }
 
-  if (PassedFlags.find(',') == StringRef::npos) {
+  if (TargetFlag.find(',') == StringRef::npos) {
     // If the flag is in the form of "--autocomplete=-foo",
     // we were requested to print out all option names that start with "-foo".
     // For example, "--autocomplete=-fsyn" is expanded to "-fsyntax-only".
-    SuggestedCompletions = Opts->findByPrefix(PassedFlags, DisableFlags);
+    SuggestedCompletions = Opts->findByPrefix(TargetFlag, DisableFlags);
 
     // We have to query the -W flags manually as they're not in the OptTable.
     // TODO: Find a good way to add them to OptTable instead and them remove
     // this code.
     for (StringRef S : DiagnosticIDs::getDiagnosticFlags())
-      if (S.startswith(PassedFlags))
+      if (S.startswith(TargetFlag))
         SuggestedCompletions.push_back(S);
   } else {
     // If the flag is in the form of "--autocomplete=foo,bar", we were
@@ -1191,7 +1195,7 @@
     // "bar". For example,
     // "--autocomplete=-stdlib=,l" is expanded to "libc++" and "libstdc++".
     StringRef Option, Arg;
-    std::tie(Option, Arg) = PassedFlags.split(',');
+    std::tie(Option, Arg) = TargetFlag.split(',');
     SuggestedCompletions = Opts->suggestValueCompletions(Option, Arg);
   }
 
Index: clang/test/Driver/autocomplete.c
===================================================================
--- clang/test/Driver/autocomplete.c
+++ clang/test/Driver/autocomplete.c
@@ -4,7 +4,6 @@
 
 // Some corner cases.
 // RUN: %clang --autocomplete= | FileCheck %s -check-prefix=ALL_FLAGS
-// RUN: %clang --autocomplete=# | FileCheck %s -check-prefix=ALL_FLAGS
 // Let's pick some example flags that are hopefully unlikely to change.
 // ALL_FLAGS: -fast
 // ALL_FLAGS: -fastcp
@@ -93,10 +92,6 @@
 // MRELOCMODELALL-NEXT: ropi-rwpi
 // MRELOCMODELALL-NEXT: rwpi
 // MRELOCMODELALL-NEXT: static
-// RUN: %clang --autocomplete=-mrelocation-mode | FileCheck %s -check-prefix=MRELOCMODEL_CLANG
-// MRELOCMODEL_CLANG-NOT: -mrelocation-model
-// RUN: %clang --autocomplete=#-mrelocation-mode | FileCheck %s -check-prefix=MRELOCMODEL_CC1
-// MRELOCMODEL_CC1: -mrelocation-model
 // RUN: %clang --autocomplete=-Wma | FileCheck %s -check-prefix=WARNING
 // WARNING: -Wmacro-redefined
 // WARNING-NEXT: -Wmain
@@ -110,3 +105,16 @@
 // ANALYZER: unix.Malloc
 // RUN: %clang --autocomplete=-std=, | FileCheck %s -check-prefix=STDVAL
 // STDVAL: c99
+//
+// Clang shouldn't autocomplete CC1 options unless -cc1 or -Xclang were provided
+// RUN: %clang --autocomplete=-mrelocation-mode | FileCheck %s -check-prefix=MRELOCMODEL_CLANG
+// MRELOCMODEL_CLANG-NOT: -mrelocation-model
+// RUN: %clang --autocomplete=-Xclang:-mrelocation-mode | FileCheck %s -check-prefix=MRELOCMODEL_CC1
+// RUN: %clang --autocomplete=-cc1:-mrelocation-mode | FileCheck %s -check-prefix=MRELOCMODEL_CC1
+// MRELOCMODEL_CC1: -mrelocation-model
+// Make sure it ignores passed flags unlesss they are -Xclang or -cc1
+// RUN: %clang --autocomplete=foo:bar::-fsyn | FileCheck %s -check-prefix=FSYN-CORON
+// FSYN-CORON: -fsyntax-only
+// Check if they can autocomplete values with coron
+// RUN: %clang --autocomplete=foo::bar::::-fno-sanitize-coverage=,f | FileCheck %s -check-prefix=FNOSANICOVER-CORON
+// FNOSANICOVER-CORON: func
Index: clang/utils/bash-autocomplete.sh
===================================================================
--- clang/utils/bash-autocomplete.sh
+++ clang/utils/bash-autocomplete.sh
@@ -25,11 +25,11 @@
     w2="${COMP_WORDS[$cword - 2]}"
   fi
 
-  # Clang want to know if -cc1 or -Xclang option is specified or not, because we don't want to show
-  # cc1 options otherwise.
-  if [[ "${COMP_WORDS[1]}" == "-cc1" || "$w1" == "-Xclang" ]]; then
-    arg="#"
-  fi
+  # Pass all the current command-line flags to clang, so that clang can handle
+  # these internally.
+  for i in `seq 1 $(($cword-1))`; do
+    arg="$arg${COMP_WORDS[$i]}:"
+  done
 
   # bash always separates '=' as a token even if there's no space before/after '='.
   # On the other hand, '=' is just a regular character for clang options that