diff --git a/lslopt/lslinliner.py b/lslopt/lslinliner.py
new file mode 100644
index 0000000..e2413a1
--- /dev/null
+++ b/lslopt/lslinliner.py
@@ -0,0 +1,374 @@
+#    (C) Copyright 2015-2019 Sei Lisa. All rights reserved.
+#
+#    This file is part of LSL PyOptimizer.
+#
+#    LSL PyOptimizer is free software: you can redistribute it and/or
+#    modify it under the terms of the GNU General Public License as
+#    published by the Free Software Foundation, either version 3 of the
+#    License, or (at your option) any later version.
+#
+#    LSL PyOptimizer is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with LSL PyOptimizer. If not, see <http://www.gnu.org/licenses/>.
+
+# Expand inlined functions. This could perhaps be made at parse time, but that
+# would obfuscate the source too much.
+
+from lslcommon import nr
+
+# Statement-level nodes that have at most 1 child and is of type expression
+SINGLE_OPT_EXPR_CHILD_NODES = frozenset({'DECL', 'EXPR', 'RETURN',
+    '@', 'STSW', 'JUMP', ';', 'LAMBDA'})
+
+class ENameAlreadyExists(Exception): pass
+
+class EExpansionLoop(Exception):
+    def __init__(self):
+        super(EExpansionLoop, self).__init__(u"Loop found in expansion of"
+            u" inline functions")
+
+class inliner(object):
+    def FixJumps(self, node):
+        """Change name and scope of JUMPs to point to the correct symtab entry
+        """
+        nt = node.nt
+        if nt == 'JUMP':
+            orig = self.symtab[node.scope][node.name]
+            if 'NewSymbolName' in orig:
+                node.name = orig['NewSymbolName']
+                node.scope = orig['NewSymbolScope']
+            return
+
+        if nt in SINGLE_OPT_EXPR_CHILD_NODES:
+            return
+
+        if nt == '{}':
+            for i in node.ch:
+                self.FixJumps(i)
+            return
+
+        if nt == 'IF' or nt == 'WHILE':
+            self.FixJumps(node.ch[1])
+            if len(node.ch) > 2:
+                self.FixJumps(node.ch[2])
+            return
+
+        if nt == 'DO':
+            self.FixJumps(node.ch[0])
+            return
+
+        if nt == 'FOR':
+            self.FixJumps(node.ch[3])
+            return
+
+        assert False, u"Unexpected node type: %s" % nt.decode('utf8')
+
+    def GetFuncCopy(self, node, scope=0):
+        """Get a copy of the function's body
+
+        Replaces 'return expr' with assignment+jump, 'return' with jump, and
+        existing labels with fresh labels. Also creates new symtabs for locals.
+        """
+        nt = node.nt
+        if nt == 'FNDEF':
+            # We're at the top level. Check return type and create a label,
+            # then recurse into the block.
+            assert node.ch[0].nt == '{}'
+            copy = self.GetFuncCopy(node.ch[0], node.ch[0].scope)
+            assert copy.nt == '{}'
+            self.FixJumps(copy)
+            return copy
+
+        if nt == '{}':
+            copy = node.copy()
+            copy.scope = len(self.symtab)
+            copy.ch = []
+            self.symtab.append({})
+            for i in node.ch:
+                copy.ch.append(self.GetFuncCopy(i, node.scope))
+                if i.nt == 'DECL':
+                    self.symtab[copy.scope][i.name] = \
+                        self.symtab[i.scope][i.name].copy()
+                    copy.ch[-1].scope = copy.scope
+            return copy
+
+        if nt == '@':
+            copy = node.copy()
+            oldscope = node.scope
+            oldname = node.name
+            self.lblCount += 1
+            copy.name = '___lbl__%05d' % self.lblCount
+            copy.scope = scope
+            if copy.name in self.symtab[scope]:
+                raise ENameAlreadyExists(
+                    u"Label already exists: %s" % copy.name.decode('utf8'))
+            self.symtab[scope][copy.name] = {'Type':'l', 'Scope':scope}
+            self.symtab[oldscope][oldname]['NewSymbolName'] = copy.name
+            self.symtab[oldscope][oldname]['NewSymbolScope'] = scope
+            return copy
+
+        if nt == 'RETURN':
+            newnode = nr(nt='JUMP', t=None, name=self.retlabel,
+                scope=self.retlscope)
+            if node.ch:
+                # Returns a value. Wrap in {} and add an assignment.
+                # BUG: We don't honour ExplicitCast here.
+                newnode = nr(nt='{}', t=None, scope=len(self.symtab), ch=[
+                    nr(nt='EXPR', t=self.rettype, ch=[
+                        nr(nt='=', t=self.rettype, ch=[
+                            nr(nt='IDENT', t=node.ch[0].t,
+                               name=self.retvar, scope=self.retscope)
+                            , self.GetFuncCopy(node.ch[0])
+                        ])
+                    ]), newnode
+                ])
+                self.symtab.append({})
+                self.retused = True
+            return newnode
+
+        if not node.ch:
+            return node.copy()
+
+        copy = node.copy()
+        copy.ch = []
+        for i in node.ch:
+            copy.ch.append(self.GetFuncCopy(i, scope))
+        return copy
+
+
+    def ConvertFunction(self, parent, index, scope):
+        node = parent[index]
+        fns = []
+        for i in range(len(node.ch)):
+            fns.extend(self.RecurseExpression(node.ch, i, scope))
+        fnsym = self.symtab[0][node.name]
+        rettype = fnsym['Type']
+        self.rettype = rettype
+        retvar = None
+        if rettype is not None:
+            # Returns a value. Create a local variable at the starting level.
+            self.retCount += 1
+            retvar = '___ret__%05d' % self.retCount
+            if retvar in self.symtab[scope]:
+                raise ENameAlreadyExists(u"Symbol %s already exists"
+                                         % retvar.decode('utf8'))
+            # Add the symbol to the symbol table
+            self.symtab[scope][retvar] = {'Kind':'v', 'Scope':scope,
+                                           'Type':rettype}
+            # Add the declaration to the list of statements
+            fns.append(nr(nt='DECL', t=rettype, name=retvar, scope=scope))
+
+        # Begin expansion
+        if node.name in self.expanding:
+            raise EExpansionLoop()
+
+        self.expanding.append(node.name)
+        self.retvar = retvar
+        self.retscope = scope
+        self.retlscope = scope
+        self.lblCount += 1
+        retlabel = '___rtl__%05d' % self.lblCount
+        self.retlabel = retlabel
+        self.symtab[scope][retlabel] = {'Type':'l', 'Scope':scope}
+
+        # Get a copy of the function
+        self.retused = False
+        blk = [self.GetFuncCopy(self.tree[fnsym['Loc']])]
+        retused = self.retused
+        self.RecurseStatement(blk, 0, scope)  # recursively expand functions
+
+        # Add return label if used, otherwise remove it from the symbol table
+        if retused:
+            blk.append(nr(nt='@', name=retlabel, scope=scope))
+        else:
+            del self.symtab[scope][retlabel]
+        self.expanding.pop()
+        # End expansion
+
+        if fnsym['ParamNames']:
+            # Add a new block + symbols + assignments for parameter values
+            pscope = len(self.symtab)
+            self.symtab.append({})
+            outer = nr(nt='{}', t=None, scope=pscope, ch=[])
+            for i in range(len(fnsym['ParamNames'])):
+                # Add parameter assignments and symbol table entries
+                pname = fnsym['ParamNames'][i]
+                ptype = fnsym['ParamTypes'][i]
+                value = node.ch[i]
+                self.symtab[pscope][pname] = {'Kind':'v','Type':ptype,
+                                              'Scope':pscope}
+                # BUG: We don't honour ExplicitCast here.
+                outer.ch.append(nr(nt='DECL', t=ptype, name=pname, scope=pscope,
+                                   ch=[value]))
+            outer.ch.extend(blk)
+            blk = [outer]
+
+        fns.extend(blk)
+
+        if rettype is None:
+            del parent[index]
+        else:
+            parent[index] = nr(nt='IDENT', t=rettype, name=retvar, scope=scope)
+
+        return fns
+
+    def RecurseExpression(self, parent, index, scope):
+        node = parent[index]
+        nt = node.nt
+        fns = []
+
+        if nt == 'FNCALL' and self.symtab[0][node.name].get('Inline', False):
+            fns.extend(self.ConvertFunction(parent, index, scope))
+        elif node.ch:
+            for i in range(len(node.ch)):
+                fns.extend(self.RecurseExpression(node.ch, i, scope))
+        return fns
+
+    def RecurseSingleStatement(self, parent, index, scope):
+        # Synthesize a block node whose child is the statement.
+        newscope = len(self.symtab)
+        self.symtab.append({})
+        node = nr(nt='{}', t=None, scope=newscope, ch=[parent[index]],
+            SEF=parent[index].SEF)
+
+        # Recurse into that node, so that any additions are made right there.
+        self.RecurseStatement(node.ch, 0, newscope)
+
+        # If it's no longer a single statement, promote it to a block.
+        if len(node.ch) != 1:
+            parent[index] = node
+        else:
+            # The new level won't be necessary. We can't delete the symbol
+            # table, though, because that shifts any new symbol tables.
+            assert not self.symtab[newscope]
+            parent[index] = node.ch[0]
+
+    def RecurseStatement(self, parent, index, scope):
+        node = parent[index]
+        nt = node.nt
+        child = node.ch
+        fns = None
+
+        if nt in SINGLE_OPT_EXPR_CHILD_NODES:
+            if child:
+                fns = self.RecurseExpression(child, 0, scope)
+                if nt == 'EXPR' and not node.ch:
+                    del parent[index]
+            else:
+                return
+
+        elif nt == '{}':
+            i = -len(child)
+            while i:
+                self.RecurseStatement(child, len(child)+i, node.scope)
+                i += 1
+
+        elif nt == 'IF':
+            fns = self.RecurseExpression(child, 0, scope)
+            self.RecurseSingleStatement(child, 1, scope)
+            if len(child) > 2:
+                self.RecurseSingleStatement(child, 2, scope)
+
+        # TODO: Handle loops properly
+        # Consider this:
+        #
+        #   integer f()
+        #   {
+        #       llOwnerSay("body of f");
+        #       return 1;
+        #   }
+        #
+        #   while (f())
+        #       llOwnerSay("doing stuff");
+        #
+        # In order to execute it every loop iteration, the while() loop must be
+        # converted to an if+jump:
+        #
+        #   integer ___ret__00001;
+        #   @___lbl__00001;
+        #   {
+        #       llOwnerSay("body_of_f");
+        #       __ret__00001 = 1;
+        #   }
+        #   if (___ret__00001)
+        #   {
+        #       llOwnerSay("doing stuff");
+        #       jump ___lbl__00001;
+        #   }
+        #
+        # The for loop is similar, but the initializer and iterator must be
+        # expanded as well, to convert it to a while loop.
+        #
+        # Do loops are different:
+        #
+        #   do
+        #       llOwnerSay("doing stuff");
+        #   while (f());
+        #
+        # should be converted to:
+        #
+        #   integer ___ret__00001;
+        #   do
+        #   {
+        #       llOwnerSay("doing stuff");
+        #       {
+        #           llOwnerSay("body_of_f");
+        #           __ret__00001 = 1;
+        #       }
+        #   }
+        #   while (___ret__00001);
+        #
+
+        elif nt == 'DO':
+            self.RecurseSingleStatement(child, 0, scope)
+            fns = self.RecurseExpression(child, 1, scope)
+
+        elif nt == 'WHILE':
+            fns = self.RecurseExpression(child, 0, scope)
+            self.RecurseSingleStatement(child, 1, scope)
+
+        elif nt == 'FOR':
+            assert child[0].nt == 'EXPRLIST'
+            assert child[2].nt == 'EXPRLIST'
+            fns = []
+            for i in range(len(child[0].ch)):
+                fns.extend(self.RecurseExpression(child[0].ch, i, scope))
+            fns.extend(self.RecurseExpression(child, 1, scope))
+            for i in range(len(child[2].ch)):
+                fns.extend(self.RecurseExpression(child[2].ch, i, scope))
+            self.RecurseSingleStatement(child, 3, scope)
+
+        else:
+            assert False, u"Unexpected node type: %s" % nt.decode('utf8')
+
+        if fns:
+            parent[index:index] = fns
+
+    def inline(self, tree, symtab):
+        self.tree = tree
+        self.symtab = symtab
+        self.retCount = 0
+        self.lblCount = 0
+        self.expanding = []
+        for i in range(len(tree)):
+            if tree[i].nt == 'STDEF':
+                for j in range(len(tree[i].ch)):  # for each event in the state
+                    self.RecurseStatement(tree[i].ch[j].ch, 0,
+                                           tree[i].ch[j].ch[0].scope)
+            elif (tree[i].nt == 'FNDEF'
+                  and not symtab[tree[i].scope][tree[i].name].get('Inline',
+                                                                  False)
+                 ):
+                # Must be an UDF
+                self.RecurseStatement(tree[i].ch, 0, tree[i].ch[0].scope)
+
+        # Remove all inline function definitions
+        for i in range(len(tree)):
+            if (tree[i].nt == 'FNDEF'
+                  and symtab[tree[i].scope][tree[i].name].get('Inline', False)
+               ):
+                tree[i] = nr(nt='LAMBDA', t=None)
diff --git a/lslopt/lslparse.py b/lslopt/lslparse.py
index 963ed46..1baf210 100644
--- a/lslopt/lslparse.py
+++ b/lslopt/lslparse.py
@@ -1011,7 +1011,8 @@ class parser(object):
                 params = (['list', 'integer', 'list'],
                           ['L', 'i', 'v'])
                 self.AddSymbol('f', 0, 'lazy_list_set', Loc=self.usedspots,
-                    Type='list', ParamTypes=params[0], ParamNames=params[1])
+                    Type='list', ParamTypes=params[0], ParamNames=params[1],
+                    Inline=False)
                 self.AddSymbol('v', paramscope, 'L', Type='list')
                 self.AddSymbol('v', paramscope, 'i', Type='integer')
                 self.AddSymbol('v', paramscope, 'v', Type='list')
@@ -2507,16 +2508,22 @@ list lazy_list_set(list L, integer i, list v)
                 self.NextToken()
                 self.localevents = None
                 self.locallabels = set()
+                force_inline = False
+                if (self.enable_inline and self.tok[0] == 'IDENT'
+                   and self.tok[1] == 'inline'):
+                    self.NextToken()
+                    force_inline = True
                 body = self.Parse_code_block(typ)
                 del self.locallabels
                 if typ and not getattr(body, 'LIR', False):  # is LastIsReturn flag set?
                     raise EParseCodePathWithoutRet(self)
                 paramscope = self.scopeindex
                 self.AddSymbol('f', 0, name, Loc=len(self.tree), Type=typ,
+                    Inline=force_inline,
                     ParamTypes=params[0], ParamNames=params[1])
                 self.tree.append(nr(nt='FNDEF', t=typ, name=name, scope=0,
-                    pscope=paramscope,
-                    ptypes=params[0], pnames=params[1], ch=[body]))
+                    pscope=paramscope, ptypes=params[0], pnames=params[1],
+                    ch=[body]))
                 self.PopScope()
                 assert self.scopeindex == 0
             else:
@@ -2667,6 +2674,8 @@ list lazy_list_set(list L, integer i, list v)
                                 break
                             self.NextToken()
                     self.NextToken()
+                    if self.tok[0] == 'IDENT' and self.tok[1] == 'inline':
+                        self.NextToken()
                     if self.tok[0] != '{':
                         return ret
                     self.NextToken()  # Enter the first brace
@@ -2845,6 +2854,9 @@ list lazy_list_set(list L, integer i, list v)
         # coding pattern is normally easy to work around anyway.
         self.optenabled = 'optimize' in options
 
+        # Inline keyword
+        self.enable_inline = 'inline' in options
+
         # Symbol table:
         # This is a list of all local and global symbol tables.
         # The first element (0) is the global scope. Each symbol table is a
@@ -2948,6 +2960,10 @@ list lazy_list_set(list L, integer i, list v)
         del self.globals
         del self.scopestack
 
+        if self.enable_inline:
+            import lslinliner
+            lslinliner.inliner().inline(self.tree, self.symtab)
+
         treesymtab = self.tree, self.symtab
         del self.tree
         del self.symtab
diff --git a/main.py b/main.py
index a0f44d5..10d7ec8 100755
--- a/main.py
+++ b/main.py
@@ -27,7 +27,7 @@ import lslopt.lslcommon
 import lslopt.lslloadlib
 
 
-VERSION = '0.2.2beta'
+VERSION = '0.3.0beta'
 
 
 def ReportError(script, e):
@@ -274,6 +274,8 @@ Case insensitive.
                        with that name). This flag works around that limitation
                        by replacing the names of the labels in the output with
                        unique ones.
+  Inline             + Enable 'inline' keyword to force functions to be inlined
+                       (EXPERIMENTAL)
 
   Deprecated / compatibility syntax extensions options:
 
@@ -356,7 +358,7 @@ validoptions = frozenset(('extendedglobalexpr','breakcont','extendedtypecast',
     'lazylists','enableswitch','errmissingdefault','funcoverride','optimize',
     'optsigns','optfloats','constfold','dcr','shrinknames','addstrings',
     'foldtabs','warntabs','processpre','explicitcast','listlength','listadd',
-    'help',
+    'inline', 'help',
     # undocumented
     'lso','expr','rsrclimit',
     # 'clear' is handled as a special case
@@ -374,7 +376,7 @@ def main(argv):
     options = set(('extendedglobalexpr','extendedtypecast','extendedassignment',
         'allowkeyconcat','allowmultistrings','processpre','warntabs','optimize',
         'optsigns','optfloats','constfold','dcr','errmissingdefault',
-        'listlength','listadd',
+        'listlength','listadd','inline',
         ))
 
     assert not (options - validoptions), (u"Default options not present in"