diff --git a/graph.c b/graph.c
index f3226ec94a..6746d422a9 100644
--- a/graph.c
+++ b/graph.c
@@ -291,9 +291,10 @@ static int graph_is_interesting(struct git_graph *graph, struct commit *commit)
 	}
 
 	/*
-	 * Uninteresting and pruned commits won't be printed
+	 * Otherwise, use get_commit_action() to see if this commit is
+	 * interesting
 	 */
-	return (commit->object.flags & (UNINTERESTING | TREESAME)) ? 0 : 1;
+	return get_commit_action(graph->revs, commit) == commit_show;
 }
 
 static struct commit_list *next_interesting_parent(struct git_graph *graph,
diff --git a/revision.c b/revision.c
index ce24ad9a8d..35eca4a361 100644
--- a/revision.c
+++ b/revision.c
@@ -1664,7 +1664,7 @@ static inline int want_ancestry(struct rev_info *revs)
 	return (revs->rewrite_parents || revs->children.name);
 }
 
-enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
+enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit)
 {
 	if (commit->object.flags & SHOWN)
 		return commit_ignore;
@@ -1692,12 +1692,23 @@ enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
 			if (!commit->parents || !commit->parents->next)
 				return commit_ignore;
 		}
-		if (want_ancestry(revs) && rewrite_parents(revs, commit) < 0)
-			return commit_error;
 	}
 	return commit_show;
 }
 
+enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
+{
+	enum commit_action action = get_commit_action(revs, commit);
+
+	if (action == commit_show &&
+	    !revs->show_all &&
+	    revs->prune && revs->dense && want_ancestry(revs)) {
+		if (rewrite_parents(revs, commit) < 0)
+			return commit_error;
+	}
+	return action;
+}
+
 static struct commit *get_revision_1(struct rev_info *revs)
 {
 	if (!revs->commits)
diff --git a/revision.h b/revision.h
index b10984b603..9d0dddbcbc 100644
--- a/revision.h
+++ b/revision.h
@@ -168,6 +168,7 @@ enum commit_action {
 	commit_error
 };
 
+extern enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit);
 extern enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit);
 
 #endif
diff --git a/t/t6015-rev-list-show-all-parents.sh b/t/t6015-rev-list-show-all-parents.sh
new file mode 100755
index 0000000000..8b146fb432
--- /dev/null
+++ b/t/t6015-rev-list-show-all-parents.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+
+test_description='--show-all --parents does not rewrite TREESAME commits'
+
+. ./test-lib.sh
+
+test_expect_success 'set up --show-all --parents test' '
+	test_commit one foo.txt &&
+	commit1=`git rev-list -1 HEAD` &&
+	test_commit two bar.txt &&
+	commit2=`git rev-list -1 HEAD` &&
+	test_commit three foo.txt &&
+	commit3=`git rev-list -1 HEAD`
+	'
+
+test_expect_success '--parents rewrites TREESAME parents correctly' '
+	echo $commit3 $commit1 > expected &&
+	echo $commit1 >> expected &&
+	git rev-list --parents HEAD -- foo.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--parents --show-all does not rewrites TREESAME parents' '
+	echo $commit3 $commit2 > expected &&
+	echo $commit2 $commit1 >> expected &&
+	echo $commit1 >> expected &&
+	git rev-list --parents --show-all HEAD -- foo.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_done
diff --git a/t/t6016-rev-list-graph-simplify-history.sh b/t/t6016-rev-list-graph-simplify-history.sh
new file mode 100755
index 0000000000..27fd52b7be
--- /dev/null
+++ b/t/t6016-rev-list-graph-simplify-history.sh
@@ -0,0 +1,276 @@
+#!/bin/sh
+
+# There's more than one "correct" way to represent the history graphically.
+# These tests depend on the current behavior of the graphing code.  If the
+# graphing code is ever changed to draw the output differently, these tests
+# cases will need to be updated to know about the new layout.
+
+test_description='--graph and simplified history'
+
+. ./test-lib.sh
+
+test_expect_success 'set up rev-list --graph test' '
+	# 3 commits on branch A
+	test_commit A1 foo.txt &&
+	test_commit A2 bar.txt &&
+	test_commit A3 bar.txt &&
+	git branch -m master A &&
+
+	# 2 commits on branch B, started from A1
+	git checkout -b B A1 &&
+	test_commit B1 foo.txt &&
+	test_commit B2 abc.txt &&
+
+	# 2 commits on branch C, started from A2
+	git checkout -b C A2 &&
+	test_commit C1 xyz.txt &&
+	test_commit C2 xyz.txt &&
+
+	# Octopus merge B and C into branch A
+	git checkout A &&
+	git merge B C &&
+	git tag A4
+
+	test_commit A5 bar.txt &&
+
+	# More commits on C, then merge C into A
+	git checkout C &&
+	test_commit C3 foo.txt &&
+	test_commit C4 bar.txt &&
+	git checkout A &&
+	git merge -s ours C &&
+	git tag A6
+
+	test_commit A7 bar.txt &&
+
+	# Store commit names in variables for later use
+	A1=$(git rev-parse --verify A1) &&
+	A2=$(git rev-parse --verify A2) &&
+	A3=$(git rev-parse --verify A3) &&
+	A4=$(git rev-parse --verify A4) &&
+	A5=$(git rev-parse --verify A5) &&
+	A6=$(git rev-parse --verify A6) &&
+	A7=$(git rev-parse --verify A7) &&
+	B1=$(git rev-parse --verify B1) &&
+	B2=$(git rev-parse --verify B2) &&
+	C1=$(git rev-parse --verify C1) &&
+	C2=$(git rev-parse --verify C2) &&
+	C3=$(git rev-parse --verify C3) &&
+	C4=$(git rev-parse --verify C4)
+	'
+
+test_expect_success '--graph --all' '
+	rm -f expected &&
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "| * $C3" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "| |     " >> expected &&
+	echo "|  \\    " >> expected &&
+	echo "*-. \\   $A4" >> expected &&
+	echo "|\\ \\ \\  " >> expected &&
+	echo "| | |/  " >> expected &&
+	echo "| | * $C2" >> expected &&
+	echo "| | * $C1" >> expected &&
+	echo "| * | $B2" >> expected &&
+	echo "| * | $B1" >> expected &&
+	echo "* | | $A3" >> expected &&
+	echo "| |/  " >> expected &&
+	echo "|/|   " >> expected &&
+	echo "* | $A2" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A1" >> expected &&
+	git rev-list --graph --all > actual &&
+	test_cmp expected actual
+	'
+
+# Make sure the graph_is_interesting() code still realizes
+# that undecorated merges are interesting, even with --simplify-by-decoration
+test_expect_success '--graph --simplify-by-decoration' '
+	rm -f expected &&
+	git tag -d A4
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "| * $C3" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "| |     " >> expected &&
+	echo "|  \\    " >> expected &&
+	echo "*-. \\   $A4" >> expected &&
+	echo "|\\ \\ \\  " >> expected &&
+	echo "| | |/  " >> expected &&
+	echo "| | * $C2" >> expected &&
+	echo "| | * $C1" >> expected &&
+	echo "| * | $B2" >> expected &&
+	echo "| * | $B1" >> expected &&
+	echo "* | | $A3" >> expected &&
+	echo "| |/  " >> expected &&
+	echo "|/|   " >> expected &&
+	echo "* | $A2" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A1" >> expected &&
+	git rev-list --graph --all --simplify-by-decoration > actual &&
+	test_cmp expected actual
+	'
+
+# Get rid of all decorations on branch B, and graph with it simplified away
+test_expect_success '--graph --simplify-by-decoration prune branch B' '
+	rm -f expected &&
+	git tag -d B2
+	git tag -d B1
+	git branch -d B
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "| * $C3" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "* |   $A4" >> expected &&
+	echo "|\\ \\  " >> expected &&
+	echo "| |/  " >> expected &&
+	echo "| * $C2" >> expected &&
+	echo "| * $C1" >> expected &&
+	echo "* | $A3" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A2" >> expected &&
+	echo "* $A1" >> expected &&
+	git rev-list --graph --simplify-by-decoration --all > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph --full-history -- bar.txt' '
+	rm -f expected &&
+	git tag -d B2
+	git tag -d B1
+	git branch -d B
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "* |   $A4" >> expected &&
+	echo "|\\ \\  " >> expected &&
+	echo "| |/  " >> expected &&
+	echo "* | $A3" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A2" >> expected &&
+	git rev-list --graph --full-history --all -- bar.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph --full-history --simplify-merges -- bar.txt' '
+	rm -f expected &&
+	git tag -d B2
+	git tag -d B1
+	git branch -d B
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "* | $A3" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A2" >> expected &&
+	git rev-list --graph --full-history --simplify-merges --all \
+		-- bar.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph -- bar.txt' '
+	rm -f expected &&
+	git tag -d B2
+	git tag -d B1
+	git branch -d B
+	echo "* $A7" >> expected &&
+	echo "* $A5" >> expected &&
+	echo "* $A3" >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A2" >> expected &&
+	git rev-list --graph --all -- bar.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph --sparse -- bar.txt' '
+	rm -f expected &&
+	git tag -d B2
+	git tag -d B1
+	git branch -d B
+	echo "* $A7" >> expected &&
+	echo "* $A6" >> expected &&
+	echo "* $A5" >> expected &&
+	echo "* $A4" >> expected &&
+	echo "* $A3" >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "| * $C3" >> expected &&
+	echo "| * $C2" >> expected &&
+	echo "| * $C1" >> expected &&
+	echo "|/  " >> expected &&
+	echo "* $A2" >> expected &&
+	echo "* $A1" >> expected &&
+	git rev-list --graph --sparse --all -- bar.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph ^C4' '
+	rm -f expected &&
+	echo "* $A7" >> expected &&
+	echo "* $A6" >> expected &&
+	echo "* $A5" >> expected &&
+	echo "*   $A4" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $B2" >> expected &&
+	echo "| * $B1" >> expected &&
+	echo "* $A3" >> expected &&
+	git rev-list --graph --all ^C4 > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--graph ^C3' '
+	rm -f expected &&
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "* $A5" >> expected &&
+	echo "*   $A4" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $B2" >> expected &&
+	echo "| * $B1" >> expected &&
+	echo "* $A3" >> expected &&
+	git rev-list --graph --all ^C3 > actual &&
+	test_cmp expected actual
+	'
+
+# I don't think the ordering of the boundary commits is really
+# that important, but this test depends on it.  If the ordering ever changes
+# in the code, we'll need to update this test.
+test_expect_success '--graph --boundary ^C3' '
+	rm -f expected &&
+	echo "* $A7" >> expected &&
+	echo "*   $A6" >> expected &&
+	echo "|\\  " >> expected &&
+	echo "| * $C4" >> expected &&
+	echo "* | $A5" >> expected &&
+	echo "| |     " >> expected &&
+	echo "|  \\    " >> expected &&
+	echo "*-. \\   $A4" >> expected &&
+	echo "|\\ \\ \\  " >> expected &&
+	echo "| * | | $B2" >> expected &&
+	echo "| * | | $B1" >> expected &&
+	echo "* | | | $A3" >> expected &&
+	echo "o | | | $A2" >> expected &&
+	echo "|/ / /  " >> expected &&
+	echo "o | | $A1" >> expected &&
+	echo " / /  " >> expected &&
+	echo "| o $C3" >> expected &&
+	echo "|/  " >> expected &&
+	echo "o $C2" >> expected &&
+	git rev-list --graph --boundary --all ^C3 > actual &&
+	test_cmp expected actual
+	'
+
+test_done