buildman: Drop comment about Ctrl-C problem

index 5a709c6ff9e..d688b7cf006 100644
@@ -1169,8 +1169,6 @@ access to log files. Also it would be nice if buildman could 'hunt' for
 problems, perhaps by building a few boards for each arch, or checking
 commits for changed files and building only boards which use those files.
 
-A specific problem to fix is that Ctrl-C does not exit buildman cleanly when
-multiple builder threads are active.
 
 Credits
 =======

index d688b7cf006..56a99c70a2a 100644
@@ -1046,6 +1046,16 @@ value for 'altbootcmd', but lost one for ' altbootcmd'.
 
 The -U option uses the u-boot.env files which are produced by a build.
 
+
+Building with clang
+===================
+
+To build with clang (sandbox only), use the -O option to override the
+toolchain. For example:
+
+   buildman -O clang-7 --board sandbox
+
+
 Other options
 =============
 

index 93d09ca08d7..832a5145d28 100644
@@ -74,6 +74,8 @@ def ParseArgs():
     parser.add_option('-o', '--output-dir', type='string',
           dest='output_dir', default='..',
           help='Directory where all builds happen and buildman has its workspace (default is ../)')
+    parser.add_option('-O', '--override-toolchain', type='string',
+          help="Override host toochain to use for sandbox (e.g. 'clang-7')")
     parser.add_option('-Q', '--quick', action='store_true',
           default=False, help='Do a rough build, with limited warning resolution')
     parser.add_option('-p', '--full-path', action='store_true',

index c900211510e..27916d3c355 100644
@@ -141,7 +141,7 @@ def DoBuildman(options, args, toolchains=None, make_func=None, boards=None,
 
     no_toolchains = toolchains is None
     if no_toolchains:
-        toolchains = toolchain.Toolchains()
+        toolchains = toolchain.Toolchains(options.override_toolchain)
 
     if options.fetch_arch:
         if options.fetch_arch == 'list':

index 4b35f400e97..a4a2e0e73a1 100644
@@ -54,9 +54,11 @@ class Toolchain:
         arch: Architecture of toolchain as determined from the first
                 component of the filename. E.g. arm-linux-gcc becomes arm
         priority: Toolchain priority (0=highest, 20=lowest)
+        override_toolchain: Toolchain to use for sandbox, overriding the normal
+                one
     """
     def __init__(self, fname, test, verbose=False, priority=PRIORITY_CALC,
-                 arch=None):
+                 arch=None, override_toolchain=None):
         """Create a new toolchain object.
 
         Args:

@@ -68,6 +70,7 @@ class Toolchain:
         """
         self.gcc = fname
         self.path = os.path.dirname(fname)
+        self.override_toolchain = override_toolchain
 
         # Find the CROSS_COMPILE prefix to use for U-Boot. For example,
         # 'arm-linux-gnueabihf-gcc' turns into 'arm-linux-gnueabihf-'.

@@ -81,6 +84,8 @@ class Toolchain:
             self.arch = arch
         else:
             self.arch = self.cross[:pos] if pos != -1 else 'sandbox'
+        if self.arch == 'sandbox' and override_toolchain:
+            self.gcc = override_toolchain
 
         env = self.MakeEnvironment(False)
 

@@ -154,7 +159,10 @@ class Toolchain:
         env = dict(os.environ)
         wrapper = self.GetWrapper()
 
-        if full_path:
+        if self.override_toolchain:
+            env['HOSTCC'] = self.override_toolchain
+            env['CC'] = self.override_toolchain
+        elif full_path:
             env['CROSS_COMPILE'] = wrapper + os.path.join(self.path, self.cross)
         else:
             env['CROSS_COMPILE'] = wrapper + self.cross

@@ -180,10 +188,11 @@ class Toolchains:
         paths: List of paths to check for toolchains (may contain wildcards)
     """
 
-    def __init__(self):
+    def __init__(self, override_toolchain=None):
         self.toolchains = {}
         self.prefixes = {}
         self.paths = []
+        self.override_toolchain = override_toolchain
         self._make_flags = dict(bsettings.GetItems('make-flags'))
 
     def GetPathList(self, show_warning=True):

@@ -234,7 +243,8 @@ class Toolchains:
             priority: Priority to use for this toolchain
             arch: Toolchain architecture, or None if not known
         """
-        toolchain = Toolchain(fname, test, verbose, priority, arch)
+        toolchain = Toolchain(fname, test, verbose, priority, arch,
+                              self.override_toolchain)
         add_it = toolchain.ok
         if toolchain.arch in self.toolchains:
             add_it = (toolchain.priority <

index a061f02399c..59a00d065e3 100644
@@ -109,16 +109,9 @@ script:
  #
  # From buildman, exit code 129 means warnings only.  If we've been asked to
  # use clang only do one configuration.
- - if [[ "${TOOLCHAIN}" == "clang" ]]; then
+ - if [[ "${BUILDMAN}" != "" ]]; then
      ret=0;
-     make O=../.bm-work/${TEST_PY_BD} HOSTCC=clang-7 CC=clang-7 -j$(nproc)
-       KCFLAGS=-Werror sandbox_config all || ret=$?;
-     if [[ $ret -ne 0 ]]; then
-       exit $ret;
-     fi;
-   elif [[ "${BUILDMAN}" != "" ]]; then
-     ret=0;
-     tools/buildman/buildman -P -E ${BUILDMAN} || ret=$?;
+     tools/buildman/buildman -P -E ${BUILDMAN} ${OVERRIDE}|| ret=$?;
      if [[ $ret -ne 0 && $ret -ne 129 ]]; then
        tools/buildman/buildman -sdeP ${BUILDMAN};
        exit $ret;

@@ -343,7 +336,7 @@ matrix:
       env:
         - TEST_PY_BD="sandbox"
           BUILDMAN="^sandbox$"
-          TOOLCHAIN="clang"
+          OVERRIDE="clang-7"
     - name: "test/py sandbox_spl"
       env:
         - TEST_PY_BD="sandbox_spl"